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Internet Draft Cengiz Alaettinoglu ExpiresJuly 15,August 10, 1999 USC/Information Sciences Institutedraft-ietf-rps-rpsl-v2-01draft-ietf-rps-rpsl-v2-02 Curtis Villamizar ANS Elise Gerich At Home Network David Kessens Qwest Communications David Meyer University of Oregon Tony Bates Cisco Systems Daniel Karrenberg RIPE Marten Terpstra Bay NetworksJanuary 15,February 10, 1999 Routing Policy Specification Language (RPSL) Status of this Memo RPSL allows a network operator to be able to specify routing policies at various levels in the Internet hierarchy; for example at the Autonomous System (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that low level router configurations can be generated from them. RPSL is extensible; new routing protocols and new protocol features can be introduced at any time. This document is anInternet Draft,Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. It can be found asdraft-ietf-rps- rpsl-v2-01draft-ietf-rps-rpsl-v2-02 in any standard internet drafts repository. Internet Drafts are working documents of the Internet Engineering Task Force (IETF), its Areas, and its Working Groups. Note that other groups may also distribute working documents as Internet Drafts. Internet Drafts are draft documents valid for a maximum of six months. Internet Drafts may be updated, replaced, or obsoleted by other documents at any time. It is not appropriate to use Internet Drafts as reference material, or to cite them other than as a ``working draft'' or ``work in progress.'' Please check the I-D abstract listing contained in each Internet Draft Internet Draft RPSL February 10, 1999 directory to learn the current status of this or any other Internet Draft. Alaettinoglu et. al. Expires August 10, 1999 [Page 2] Internet Draft RPSLJanuary 15,February 10, 1999 Contents 1 Introduction35 2 RPSL Names, Reserved Words, and Representation46 3 Contact Information79 3.1 mntner Class . . . . . . . . . . . . . . . . . . . . . . . . . . .79 3.2 person Class . . . . . . . . . . . . . . . . . . . . . . . . . . .911 3.3 role Class . . . . . . . . . . . . . . . . . . . . . . . . . . . .1012 4 route Class1013 5 Set Classes1114 5.1route-setas-set Class . . . . . . . . . . . . . . . . . . . . . . . . . .12. 15 5.2as-setroute-set Class . . . . . . . . . . . . . . . . . . . . . . . . . .. 1416 5.3 Predefined Set Objects . . . . . . . . . . . . . . . . . . . . . .1518 5.4Hierarchical Set Names . . .Filters and filter-set Class . . . . . . . . . . . . . . . . . . .16 6 aut-num18 5.5 rtr-set Class16 6.1 import Attribute: Import Policy Specification . . .. . . . . . .17 6.1.1Peering Specification . . .. . . . . . . . . . . . . . . . . .18 6.1.2Action Specification . .. . 23 5.6 Peerings and peering-set Class . . . . . . . . . . . . . . . . . .20 6.1.3Filter24 6 aut-num Class 27 6.1 import Attribute: Import Policy Specification . . . . . . . . . . 28 6.1.1Action Specification . . . . . . . . . . . .21 6.1.4Example Policy Expressions . . . . . . . . .. . . . . . . . . .2528 6.2 export Attribute: Export Policy Specification . . . . . . . . . .2529 6.3 Other Routing Protocols, Multi-Protocol Routing Protocols, and Injecting Routes Between Protocols . . . . . . . . . . . . . . . . .2630 6.4 Ambiguity Resolution . . . . . . . . . . . . . . . . . . . . . . .2731 6.5 default Attribute: Default Policy Specification . . . . . . . . .30 Alaettinoglu et. al. Expires July 15, 1999 [Page 2] Internet Draft RPSL January 15, 199934 6.6 Structured Policy Specification . . . . . . . . . . . . . . . . . .3135 Alaettinoglu et. al. Expires August 10, 1999 [Page 3] Internet Draft RPSL February 10, 1999 7 dictionary Class3438 7.1 Initial RPSL Dictionary and Example Policy Actions and Filters . .3842 8 Advanced route Class4246 8.1 Specifying Aggregate Routes . . . . . . . . . . . . . . . . . . . .4246 8.1.1Interaction with policies in aut-num class . . . . . . . . . . .4650 8.1.2Ambiguity resolution with overlapping aggregates . . . . . . . .4851 8.2 Specifying Static Routes . . . . . . . . . . . . . . . . . . . . .4953 9 inet-rtr Class4953 10Extending RPSL5155 10.1Extensions by changing the dictionary class . . . . . . . . . . . .5155 10.2Extensions by adding new attributes to existing classes . . . . . .5156 10.3Extensions by adding new classes . . . . . . . . . . . . . . . . .5256 10.4Extensions by changing the syntax of existing RPSL attributes . . .5256 11Security Consideration5257 12Acknowledgements5357 A Routing Registry Sites5559 B Grammar Rules5559 C Changes from RFC 22806167 D Authors' Addresses6268 Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page3]4] Internet Draft RPSLJanuary 15,February 10, 1999 1 Introduction This Internet Draft is the reference document for the Routing Policy Specification Language (RPSL). RPSL allows a network operator to be able to specify routing policies at various levels in the Internet hierarchy; for example at the Autonomous System (AS) level. At the same time, policies can be specified with sufficient detail in RPSL so that low level router configurations can be generated from them. RPSL is extensible; new routing protocols and new protocol features can be introduced at any time. RPSL is a replacement for the current Internet policy specification language known as RIPE-181 [6] or RFC-1786 [7]. RIPE-81 [8] was the first language deployed in the Internet for specifying routing policies. It was later replaced by RIPE-181 [6]. Through operational use of RIPE-181 it has become apparent that certain policies cannot be specified and a need for an enhanced and more generalized language is needed. RPSL addresses RIPE-181's limitations. RPSL was designed so that a view of the global routing policy can be contained in a single cooperatively maintained distributed database to improve the integrity of Internet's routing. RPSL is not designed to be a router configuration language. RPSL is designed so that router configurations can be generated from the description of the policy for one autonomous system (aut-num class) combined with the description of a router (inet-rtr class), mainly providing router ID, autonomous system number of the router, interfaces and peers of the router, and combined with a global database mappings from AS sets to ASes (as-set class), and from origin ASes and route sets to route prefixes (route and route-set classes). The accurate population of the RPSL database can help contribute toward such goals as router configurations that protect against accidental (or malicious) distribution of inaccurate routing information, verification of Internet's routing, and aggregation boundaries beyond a single AS. RPSL is object oriented; that is, objects contain pieces of policy and administrative information. These objects are registered in the Internet Routing Registry (IRR) by the authorized organizations. The registration process is beyond the scope of this document. Please refer to [1, 17, 4] for more details on the IRR. In the following sections, we present the classes that are used to define various policy and administrative objects. The "mntner" class defines entities authorized to add, delete and modify a set of objects. The "person" and "role" classes describes technical and administrative contact personnel. Autonomous systems (ASes) are specified using the "aut-num" class. Routes are specified using the "route" class. Sets ofASes and routesobjects can be defined using the"as-set""as-set", "route-set", "filter-set", "peering-set", and"route-set""rtr-set" classes. The "dictionary" class provides the extensibility to the language. The "inet-rtr" class is used to specify routers. Many of these classes were originally defined in earlier documents [6, 13, 16, 12, 5] and have all been enhanced. Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page4]5] Internet Draft RPSLJanuary 15,February 10, 1999 This document is self-contained. However, the reader is encouraged to read RIPE-181 [7] and the associated documents [13, 16, 12, 5] as they provide significant background as to the motivation and underlying principles behind RIPE-181 and consequently, RPSL. For a tutorial on RPSL, the reader should read the RPSL applications document [4]. 2 RPSL Names, Reserved Words, and Representation Each class has a set of attributes which store a piece of information about the objects of the class. Attributes can be mandatory or optional: A mandatory attribute has to be defined for all objects of the class; optional attributes can be skipped. Attributes can also be single or multiple valued. Each object is uniquely identified by a set of attributes, referred to as the class ``key''. The value of an attribute has a type. The following types are most widely used. Note that RPSL is case insensitive and only the characters from the ASCII character set can be used. <object-name>Many objects in RPSL have a name. An <object-name> is made up of letters, digits, the character underscore ``_'', and the character hyphen ``-''; the first character of a name must be a letter, and the last character of a name must be a letter or a digit. The following words are reserved by RPSL, and they can not be used as names: any as-any rs-any peeras and or not atomic from to at action accept announce except refine networks into inbound outbound Names starting with certain prefixes are reserved for certain object types. Names starting with ``as-'' are reserved for as set names. Names starting with ``rs-'' are reserved for route set names. Names starting with ``rtrs-'' are reserved for router set names. Names starting with ``fltr-'' are reserved for filter set names. Names starting with ``prng-'' are reserved for peering set names. <as-number>An AS number x is represented as the string ``ASx''. That is, the AS 226 is represented as AS226. <ipv4-address>An IPv4 address is represented as a sequence of four integers in the range from 0 to 255 separated by the character dot ``.''. For example, 128.9.128.5 represents a valid IPv4 address. In the rest of this document, we may refer to IPv4 addresses as IP addresses. Alaettinoglu et. al. Expires August 10, 1999 [Page 6] Internet Draft RPSL February 10, 1999 <address-prefix>An address prefix is represented as an IPv4 address followed by the character slash ``/'' followed by an integer in the range from 0 to 32. The following are valid address prefixes:Alaettinoglu et. al. Expires July 15, 1999 [Page 5] Internet Draft RPSL January 15, 1999128.9.128.5/32, 128.9.0.0/16, 0.0.0.0/0; and the following address prefixes are invalid: 0/0, 128.9/16 since 0 or 128.9 are not strings containing four integers. <address-prefix-range>An address prefix range is an address prefix followed by an optional range operator. The range operators are: ^- is the exclusive more specifics operator; it stands for the more specifics of the address prefix excluding the address prefix itself. For example, 128.9.0.0/16^- contains all the more specifics of 128.9.0.0/16 excluding 128.9.0.0/16. ^+ is the inclusive more specifics operator; it stands for the more specifics of the address prefix including the address prefix itself. For example, 5.0.0.0/8^+ contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8. ^n where n is an integer, stands for all the length n specifics of the address prefix. For example, 30.0.0.0/8^16 contains all the more specifics of 30.0.0.0/8 which are of length 16 such as 30.9.0.0/16. ^n-m where n and m are integers, stands for all the length n to length m specifics of the address prefix. For example, 30.0.0.0/8^24-32 contains all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28. Range operators can also be applied to address prefix sets. In this case, they distribute over the members of the set. For example, for a route-set (defined later) rs-foo, rs-foo^+ contains all the inclusive more specifics of all the prefixes in rs-foo. It is an error to follow a range operator with another one (e.g. 30.0.0.0/8^24-28^+ is an error). However, a range operator can be applied to an address prefix set that has address prefix ranges in it (e.g. {30.0.0.0/8^24-28}^27-30 is not an error). In this case, the outer operator ^n-m distributes over the inner operator ^k-l and becomes the operator ^max(n,k)-m if m is greater than or equal to max(n,k), or otherwise, the prefix is deleted from the set. Note that the operator ^n is equivalent to ^n-n; prefix/l^+ is equivalent to prefix/l^l-32; prefix/l^- is equivalent to prefix/l^(l+1)-32; {prefix/l^n-m}^+ is equivalent to {prefix/l^n-32}; and {prefix/l^n-m}^- is equivalent to {prefix/l^(n+1)-32}. For example, {128.9.0.0/16^+}^- == {128.9.0.0/16^-} {128.9.0.0/16^-}^+ == {128.9.0.0/16^-}{128.9.0.0/16^17}^24 == {128.9.0.0/16^24} {128.9.0.0/16^20-24}^26-28 == {128.9.0.0/16^26-28} {128.9.0.0/16^20-24}^22-28 == {128.9.0.0/16^22-28}Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page6]7] Internet Draft RPSLJanuary 15,February 10, 1999 {128.9.0.0/16^17}^24 == {128.9.0.0/16^24} {128.9.0.0/16^20-24}^26-28 == {128.9.0.0/16^26-28} {128.9.0.0/16^20-24}^22-28 == {128.9.0.0/16^22-28} {128.9.0.0/16^20-24}^18-28 == {128.9.0.0/16^20-28} {128.9.0.0/16^20-24}^18-22 == {128.9.0.0/16^20-22} {128.9.0.0/16^20-24}^18-19 == {} <date>A date is represented as an eight digit integer of the form YYYYMMDD where YYYY represents the year, MM represents the month of the year (01 through 12), and DD represents the day of the month (01 through 31). All dates are in UTC unless otherwise specified. For example, June 24, 1996 is represented as 19960624. <email-address>is as described in RFC-822[10]. <dns-name>is as described in RFC-1034[18]. <nic-handle>is a uniquely assigned identifier[15] used by routing, address allocation, and other registries to unambiguously refer to contact information. person and role classes map NIC handles to actual person names, and contact information. <free-form>is a sequence of ASCII characters. <X-name>is a name of an object of type X. That is <mntner-name> is a name of a mntner object. <registry-name>is a name of an IRR registry. The routing registries are listed in Appendix A. A value of an attribute may also be a list of one of these types. A list is represented by separating the list members by commas ``,''. For example, ``AS1, AS2, AS3, AS4'' is a list of AS numbers. Note that being list valued and being multiple valued are orthogonal. A multiple valued attribute has more than one value, each of which may or may not be a list. On the other hand a single valued attribute may have a list value. An RPSL object is textually represented as a list of attribute-value pairs. Each attribute-value pair is written on a separate line. The attribute name starts at column 0, followed by character ``:'' and followed by the value of the attribute. The attribute which has the same name as the object's class should be specified first. The object's representation ends when a blank line is encountered. An attribute's value can be split over multiple lines, by having a space, a tab or a plus ('+') character as the first character of the continuation lines. The character ``+'' for line continuation allows attribute values to contain blank lines. More spaces may optionally be used after the continuation character to increase readability. The order of attribute-value pairs is significant. Alaettinoglu et. al. Expires August 10, 1999 [Page 8] Internet Draft RPSL February 10, 1999 An object's description may contain comments. A comment can be anywhere in an object's definition, it starts at the first ``#'' character on a line and ends at the first end-of-line character. White space characters can be used to improve readability.Alaettinoglu et. al. Expires July 15, 1999 [Page 7] Internet Draft RPSL January 15, 1999An integer can be specified using (1) the C programming language notation (e.g. 1, 12345); (2) sequence of four 1-octet integers (in the range from 0 to 255) separated by the character dot ``.'' (e.g. 1.1.1.1, 255.255.0.0), in this case a 4-octet integer is formed by concatenating these 1-octet integers in the most significant to least significant order; (3) sequence of two 2-octet integers (in the range from 0 to 65535) separated by the character colon ``:'' (e.g. 3561:70, 3582:10), in this case a 4-octet integer is formed by concatenating these 2-octet integers in the most significant to least significant order. 3 Contact Information The mntner, person and role classes, admin-c, tech-c, mnt-by, changed, and source attributes of all classes describe contact information. The mntner class also specifies authenticaiton information required to create, delete and update other objects. These classes do not specify routing policies and each registry may have different or additional requirements on them. Here we present the common denominator for completeness which is the RIPE database implementation [17]. Please consult your routing registry for the latest specification of these classes and attributes. The ``Routing Policy System Security'' document [21] describes the authenticaiton and authorization model in more detail. 3.1 mntner Class The mntner class specifies authenticaiton information required to create, delete and update RPSL objects. A provider, before he/she can create RPSL objects, first needs to create a mntner object. The attributes of the mntner class are shown in Figure 1. The mntner class was first described in [13]. The mntner attribute is mandatory and is the class key. Its value is an RPSL name. The auth attribute specifies the scheme that will be used to identify and authenticate update requests from this maintainer. It has the following syntax: auth: <scheme-id> <auth-info> E.g. auth: NONEauth: CRYPT-PW dhjsdfhruewf auth: MAIL-FROM .*@ripe\.net The <scheme-id>'s currently defined are: NONE, MAIL-FROM, PGP-KEY andAlaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page8]9] Internet Draft RPSLJanuary 15,February 10, 1999 Attribute Value Type mntner <object-name> mandatory, single-valued, class key descr <free-form> mandatory, single-valued auth see description in text mandatory, multi-valued upd-to <email-address> mandatory, multi-valued mnt-nfy <email-address> optional, multi-valued tech-c <nic-handle> mandatory, multi-valued admin-c <nic-handle> optional, multi-valued remarks <free-form> optional, multi-valued notify <email-address> optional, multi-valued mnt-by list of <mntner-name> mandatory, multi-valued changed <email-address> <date> mandatory, multi-valued source <registry-name> mandatory, single-valued Figure 1: mntner Class Attributes auth: CRYPT-PW dhjsdfhruewf auth: MAIL-FROM .*@ripe\.net The <scheme-id>'s currently defined are: NONE, MAIL-FROM, PGP-KEY and CRYPT-PW. The <auth-info> is additional information required by a particular scheme: in the case of MAIL-FROM, it is a regular expression matching valid email addresses; in the case of CRYPT-PW, it is a password in UNIX crypt format; and in the case of PGP-KEY, it is a pointer to key-certif object [23] containing the PGP public key of the user. If multiple auth attributes are specified, an update request satisfying any one of them is authenticated to be from the maintainer. The upd-to attribute is an email address. On an unauthorized update attempt of an object maintained by this maintainer, an email message will be sent to this address. The mnt-nfy attribute is an email address. A notification message will be forwarded to this email address whenever an object maintained by this maintainer is added, changed or deleted. The descr attribute is a short, free-form textual description of the object. The tech-c attribute is a technical contact NIC handle. This is someone to be contacted for technical problems such as misconfiguration. The admin-c attribute is an administrative contact NIC handle. The remarks attribute is a free text explanation or clarification. The notify attribute is an email address to which notifications of changes to this object should be sent. The mnt-by attribute is a list of mntner object names. The authorization for changes to this object is governed by any of the maintainer objects referenced. The changed attribute documents who last changed this object, and when this change was made. Its syntax has the following form:changed: <email-address> <YYYYMMDD> E.g. changed: johndoe@terabit-labs.nn 19900401Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page9]10] Internet Draft RPSLJanuary 15,February 10, 1999 changed: <email-address> <YYYYMMDD> E.g. changed: johndoe@terabit-labs.nn 19900401 The <email-address> identifies the person who made the last change. <YYYYMMDD> is the date of the change. The source attribute specifies the registry where the object is registered. Figure 2 shows an example mntner object. In the example, UNIX crypt format password authentication is used. mntner: RIPE-NCC-MNT descr: RIPE-NCC Maintainer admin-c: DK58 tech-c: OPS4-RIPE upd-to: ops@ripe.net mnt-nfy: ops-fyi@ripe.net auth: CRYPT-PW lz1A7/JnfkTtI mnt-by: RIPE-NCC-MNT changed: ripe-dbm@ripe.net 19970820 source: RIPE Figure 2: An example mntner object. The descr, tech-c, admin-c, remarks, notify, mnt-by, changed and source attributes are attributes of all RPSL classes. Their syntax, semantics, and mandatory, optional, multi-valued, or single-valued status are the same for for all RPSL classes. Only exception to this is the admin-c attribute which is mandatory for the aut-num class. We do not further discuss them in other sections. 3.2 person Class A person class is used to describe information about people. Even though it does not describe routing policy, we still describe it here briefly since many policy objects make reference to person objects. The person class was first described in [16].Attribute Value Type person <free-form> mandatory, single-valued nic-hdl <nic-handle> mandatory, single-valued, class key address <free-form> mandatory, multi-valued phone see description in text mandatory, multi-valued fax-no same as phone optional, multi-valued e-mail <email-address> mandatory, multi-valued Figure 3: person Class AttributesThe attributes of the person class are shown in Figure 3. The person attribute is the full name of the person. The phone and the fax-noAlaettinoglu et. al. Expires July 15, 1999 [Page 10] Internet Draft RPSL January 15, 1999attributes have the following syntax: phone: +<country-code> <city> <subscriber> [ext. <extension>] E.g.: phone: +31 20 12334676 Alaettinoglu et. al. Expires August 10, 1999 [Page 11] Internet Draft RPSL February 10, 1999 Attribute Value Type person <free-form> mandatory, single-valued nic-hdl <nic-handle> mandatory, single-valued, class key address <free-form> mandatory, multi-valued phone see description in text mandatory, multi-valued fax-no same as phone optional, multi-valued e-mail <email-address> mandatory, multi-valued Figure 3: person Class Attributes phone: +44 123 987654 ext. 4711 Figure 4 shows an example person object. person: Daniel Karrenberg address: RIPE Network Coordination Centre (NCC) address: Singel 258 address: NL-1016 AB Amsterdam address: Netherlands phone: +31 20 535 4444 fax-no: +31 20 535 4445 e-mail: Daniel.Karrenberg@ripe.net nic-hdl: DK58 changed: Daniel.Karrenberg@ripe.net 19970616 source: RIPE Figure 4: An example person object. 3.3 role Class The role class is similar to the person object. However, instead of describing a human being, it describes a role performed by one or more human beings. Examples include help desks, network monitoring centers, system administrators, etc. Role object is particularly useful since often a person performing a role may change, however the role itself remains. The attributes of the role class are shown in Figure 5. The nic-hdl attributes of the person and role classes share the same name space. The trouble attribute of role object may contain additional contact information to be used when a problem arises in any object that references this role object. Figure 6 shows an example role object.4 route Class Each interAS route (also referred to as an interdomain route) originated by an AS is specified using a route object. The attributes of the route class are shown in Figure 7. The route attribute is the address prefix of theAlaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page11]12] Internet Draft RPSLJanuary 15,February 10, 1999 Attribute Value Type role <free-form> mandatory, single-valued nic-hdl <nic-handle> mandatory, single-valued, class key trouble <free-form> optional, multi-valued address <free-form> mandatory, multi-valued phone see description in text mandatory, multi-valued fax-no same as phone optional, multi-valued e-mail <email-address> mandatory, multi-valued Figure 5: role Class Attributes role: RIPE NCC Operations trouble: address: Singel 258 address: 1016 AB Amsterdam address: The Netherlands phone: +31 20 535 4444 fax-no: +31 20 545 4445 e-mail: ops@ripe.net admin-c: CO19-RIPE tech-c: RW488-RIPE tech-c: JLSD1-RIPE nic-hdl: OPS4-RIPE notify: ops@ripe.net changed: roderik@ripe.net 19970926 source: RIPE Figure 6: An example role object. 4 route Class Each interAS route (also referred to as an interdomain route) originated by an AS is specified using a route object. The attributes of the route class are shown in Figure 7. The route attribute is the address prefix of the route and the origin attribute is the AS number of the AS that originates the route into the interAS routing system. The route and origin attribute pair is the class key. Figure 8 shows examples of four route objects (we do not include contact attributes such as admin-c, tech-c for brevity). Note that the last two route objects have the same address prefix, namely 128.8.0.0/16. However, they are different route objects since they are originated by different ASes (i.e. they have different keys).5 Set Classes To specify policies, it is often useful to define sets of objects. For this purpose we define two classes: route-set and as-set. These classesAlaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page12]13] Internet Draft RPSLJanuary 15,February 10, 1999 Attribute Value Type route <address-prefix> mandatory, single-valued, class key origin <as-number> mandatory, single-valued, class key member-of list of <route-set-names> optional, multi-valued see Section 5 inject see Section 8 optional, multi-valued components see Section 8 optional, single-valued aggr-bndry see Section 8 optional, single-valued aggr-mtd see Section 8 optional, single-valued export-comps see Section 8 optional,multi-valuedsingle-valued holes see Section 8 optional, multi-valued Figure 7: route Class Attributes route: 128.9.0.0/16 origin: AS226 route: 128.99.0.0/16 origin: AS226 route: 128.8.0.0/16 origin: AS1 route: 128.8.0.0/16 origin: AS2 Figure 8: Route Objects 5 Set Classes To specify policies, it is often useful to define sets of objects. For this purpose we define as-set, route-set, rtr-set, filter-set, and peering-set classes. These classes define a named set. The members of these sets can be specifiedbyeitherexplicitlydirectly by listing them in theset object'ssets' definition, orimplicitlyindirectly by havingroute and aut-nummember objects refer totheirthe sets' names, or a combination of both methods.5.1 route-set Class The attributes of the route-set class are shown in Figure 9. The route-set attribute defines theA set's nameof the set. Itis anRPSL name that startsrpsl word with``rs-''. The members attribute lists the members of the set. The members attribute is a list of address prefixes or other route-set names. Note that,the following restrictions: All as-set names start with prefix ``as-''. All route-setclassnames start with prefix ``as-''. All rtr-set names start with prefix ``rtrs-''. All filter-set names start with prefix ``fltr-''. All peering-set names start with prefix ``prng-''. For example, as-foo is a valid as-set name. Set names can also be hierarchical. A hierarchical setof route prefixes, not of RPSL route objects. Figure 10 presents some example route-set objects. The set rs-foo containsname is a sequence Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page13]14] Internet Draft RPSLJanuary 15,February 10, 1999 of set names and AS numbers separated by colons ``:''. At least one component of such a name must be an actual set name (i.e. start with one of the prefixes above). All the set name components of an hierarchical name has to be of the same type. For example, the following names are valid: AS1:AS-CUSTOMERS, AS1:RS-EXPORT:AS2, RS-EXCEPTIONS:RS-BOGUS. The purpose of an hierarchical set name is to partition the set name space so that the maintainers of the set X1 controls the whole set name space underneath, i.e. X1:...:Xn-1. Thus, a set object with name X1:...:Xn-1:Xn can only be created by the maintainer of the object with name X1:...:Xn-1. That is, only the maintainer of AS1 can create a set with name AS1:AS-FOO; and only the maintainer of AS1:AS-FOO can create a set with name AS1:AS-FOO:AS-BAR. Please see RPS Security Document [21] for details. 5.1 as-set Class The attributes of the as-set class are shown in Figure 9. The as-set attribute defines the name of the set. It is an RPSL name that starts with ``as-''. The members attribute lists the members of the set. The members attribute is a list of AS numbers, or other as-set names. Attribute Value Typeroute-setas-set <object-name> mandatory, single-valued, class key members list of<address-prefix-range><as-numbers> or optional, multi-valued<route-set-name> or <route-set-name><range-operator><as-set-names> mbrs-by-ref list of <mntner-names> optional, multi-valued Figure 9:route-setas-set Class Attributes Figure 10 presents twoaddress prefixes, namely 128.9.0.0/16 and 128.9.0.0/24.as-set objects. The setrs-baras-foo containsthe memberstwo ASes, namely AS1 and AS2. The set as-bar contains the members of the setrs-fooas-foo andthe address prefix 128.7.0.0/16.AS3, that is it contains AS1, AS2, AS3. The setrs-emptyas-empty contains no members.route-set: rs-fooas-set: as-foo as-set: as-bar as-set: as-empty members:128.9.0.0/16, 128.9.0.0/24 route-set: rs-barAS1, AS2 members:128.7.0.0/16, rs-foo route-set: rs-emptyAS3, as-foo Figure 10:route-set Objects An address prefix or a route-set name in a members attribute can be optionally followed by a range operator. For example, the following set route-set: rs-bar members: 5.0.0.0/8^+, 30.0.0.0/8^24-32, rs-foo^+ contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28, and all the more specifics of address prefixes in route set rs-foo.as-set objects. The mbrs-by-ref attribute is a list of maintainer names or the keyword ANY. If this attribute is used, therouteAS set also includesaddress prefixesASes whoserouteaut-num objects are registered by one of these maintainers and whose member-of attribute refers to the name of thisrouteAS set. If the value of a mbrs-by-ref Alaettinoglu et. al. Expires August 10, 1999 [Page 15] Internet Draft RPSL February 10, 1999 attribute is ANY, anyrouteAS object referring to therouteAS setnameis amember.member of the set. If the mbrs-by-ref attribute is missing, only theaddress prefixesASes listed in the members attribute are members of the set.Alaettinoglu et. al. Expires July 15, 1999 [Page 14] Internet Draft RPSL January 15, 1999 route-set: rs-foo mbrs-by-ref: MNTR-ME, MNTR-YOU route-set: rs-baras-set: as-foo members:128.7.0.0/16AS1, AS2 mbrs-by-ref:MNTR-YOU route: 128.9.0.0/16 origin: AS1MNTR-ME aut-num: AS3 aut-num: AS4 member-of:rs-fooas-foo member-of: as-foo mnt-by: MNTR-MEroute: 128.8.0.0/16 origin: AS2 member-of: rs-foo, rs-barmnt-by:MNTR-YOUMNTR-OTHER Figure 11:route-setas-set objects. Figure 11 presents an exampleroute-set objectsas-set object thatuseuses the mbrs-by-ref attribute. The setrs-fooas-foo containstwo address prefixes, namely 128.8.0.0/16 and 128.9.0.0/16 since the route objects for 128.8.0.0/16AS1, AS2 and128.9.0.0/16 refer toAS3. AS4 is not a member of the setname rs-foo in their member-of attribute. The set rs-bar containsas-foo even though theaddress prefixes 128.7.0.0/16 and 128.8.0.0/16. The route 128.7.0.0/16 is explicitly listed in the members attribute of rs-bar, and the routeaut-num objectfor 128.8.0.0/16 refer to the set name rs-bar in its member-of attribute. Note that, if an address prefixreferences as-foo. This islisted in a members attribute of a route set, itbecause MNTR-OTHER isa member of that route set. The route object corresponding to this address prefix doesnotneed to contain a member-of attribute referring to this set name. The member-of attribute of the route class is an additional mechanism for specifyinglisted in themembers indirectly.as-foo's mbrs-by-ref attribute. 5.2as-setroute-set Class The attributes of theas-setroute-set class are shown in Figure 12. Theas-setroute-set attribute defines the name of the set. It is an RPSL name that starts with``as-''.``rs-''. The members attribute lists the members of the set. The members attribute is a list ofAS numbers,address prefixes or otheras-setroute-set names.Figure 13 presents two as-set objects. The set as-foo contains two ASes, namely AS1 and AS2. The set as-bar contains the members ofNote that, theset as-foo and AS3, that is it contains AS1, AS2, AS3. The mbrs-by-ref attributeroute-set class is alistset of route prefixes, not ofmaintainer names or the keyword ANY. Alaettinoglu et. al. Expires July 15, 1999 [Page 15] Internet DraftRPSLJanuary 15, 1999route objects. Attribute Value Typeas-setroute-set <object-name> mandatory, single-valued, class key members list of<as-numbers><address-prefix-range> or optional, multi-valued<as-set-names><route-set-name> or <route-set-name><range-operator> mbrs-by-ref list of <mntner-names> optional, multi-valued Figure 12:as-setroute-set Class Attributesas-set: as-foo as-set: as-bar members: AS1, AS2 members: AS3, as-fooFigure13: as-set13 presents some example route-set objects.If this attribute is used, the ASThe setalso includes ASes whose aut-num objects are registered by one of these maintainersrs-foo contains two address prefixes, namely 128.9.0.0/16 andwhose member-of attribute refers to128.9.0.0/24. The set rs-bar contains thenamemembers ofthis AS set. Ifthevalue of a mbrs-by-ref attribute is ANY, any AS object referringset rs-foo and the address prefix 128.7.0.0/16. An address prefix or a route-set name in a members attribute can be optionally followed by a range operator. For example, the following set Alaettinoglu et. al. Expires August 10, 1999 [Page 16] Internet Draft RPSL February 10, 1999 route-set: rs-foo members: 128.9.0.0/16, 128.9.0.0/24 route-set: rs-bar members: 128.7.0.0/16, rs-foo Figure 13: route-set Objects route-set: rs-bar members: 5.0.0.0/8^+, 30.0.0.0/8^24-32, rs-foo^+ contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28, and all theASmore specifics of address prefixes in route set rs-foo. The mbrs-by-ref attribute is amemberlist of maintainer names or the keyword ANY. If this attribute is used, the route set also includes address prefixes whose route objects are registered by one of these maintainers and whose member-of attribute refers to the name of this route set. If the value of a mbrs-by-ref attribute is ANY, any route object referring to the route set name is a member. If the mbrs-by-ref attribute is missing, only theASesaddress prefixes listed in the members attribute are members of the set.as-set: as-fooroute-set: rs-foo mbrs-by-ref: MNTR-ME, MNTR-YOU route-set: rs-bar members:AS1, AS2128.7.0.0/16 mbrs-by-ref:MNTR-ME aut-num: AS3 aut-num: AS4 member-of: as-fooMNTR-YOU route: 128.9.0.0/16 origin: AS1 member-of:as-foors-foo mnt-by: MNTR-ME route: 128.8.0.0/16 origin: AS2 member-of: rs-foo, rs-bar mnt-by:MNTR-OTHERMNTR-YOU Figure 14:as-setroute-set objects. Figure 14 presentsanexampleas-set objectroute-set objects thatusesuse the mbrs-by-ref attribute. The setas-foors-foo containsAS1, AS2two address prefixes, namely 128.8.0.0/16 andAS3. AS4 is not a member of the set as-foo even though the aut-num object references as-foo. This is because MNTR-OTHER is not listed in128.9.0.0/16 since theas-foo's mbrs-by-ref attribute. 5.3route objects for 128.8.0.0/16 and Alaettinoglu et. al. Expires August 10, 1999 [Page 17] Internet Draft RPSL February 10, 1999 128.9.0.0/16 refer to the set name rs-foo in their member-of attribute. The set rs-bar contains the address prefixes 128.7.0.0/16 and 128.8.0.0/16. The route 128.7.0.0/16 is explicitly listed in the members attribute of rs-bar, and the route object for 128.8.0.0/16 refer to the set name rs-bar in its member-of attribute. Note that, if an address prefix is listed in a members attribute of a route set, it is a member of that route set. The route object corresponding to this address prefix does not need to contain a member-of attribute referring to this set name. The member-of attribute of the route class is an additional mechanism for specifying the members indirectly. 5.3 Predefined Set Objects In a context that expects a route set (e.g. members attribute of the route-set class), an AS number ASx defines the set of routes that are originated by ASx; and an as-set AS-X defines the set of routes that areAlaettinoglu et. al. Expires July 15, 1999 [Page 16] Internet Draft RPSL January 15, 1999originated by the ASes in AS-X. A route p is said to be originated by ASx if there is a route object for p with ASx as the value of the origin attribute. For example, in Figure 15, the route set rs-special contains 128.9.0.0/16, routes of AS1 and AS2, and routes of the ASes in AS set AS-FOO. route-set: rs-special members: 128.9.0.0/16, AS1, AS2, AS-FOO Figure 15: Use of AS numbers and AS sets in route sets. The set rs-any contains all routes registered in IRR. The set as-any contains all ASes registered in IRR. 5.4Hierarchical Set Names Set names can be hierarchical. A hierarchical set name is a sequence of set namesFilters andAS numbers separated by colons ``:''. For example, the following names are valid: AS1:AS-CUSTOMERS, AS1:RS-EXCEPTIONS, AS1:RS-EXPORT:AS2, RS-EXCEPTIONS:RS-BOGUS. All componentsfilter-set Class The attributes ofan hierarchical set name whichthe filter-set class arenot AS numbers should start with ``as-'' or ``rs-'' for as sets and route sets respectively. And at least one component must be a set name.shown in Figure 16. Asetfilter-set objectwith name X1:...:Xn-1:Xn can only be createddefines a set of routes that are matched by its filter. The filter-set attribute defines themaintainername of theobject withfilter. It is an RPSL nameX1:...:Xn-1. That is, only the maintainer of AS1 can create a setthat starts withname AS1:AS-FOO;``fltr-''. Attribute Value Type filter-set <object-name> mandatory, single-valued, class key filter <filter> mandatory, single-valued Figure 16: filter Class Attributes Alaettinoglu et. al. Expires August 10, 1999 [Page 18] Internet Draft RPSL February 10, 1999 filter-set: fltr-foo filter: { 5.0.0.0/8, 6.0.0.0/8 } filter-set: fltr-bar filter: (AS1 or fltr-foo) andonly the maintainer of AS1:AS-FOO can create a set with name AS1:AS-FOO:AS-BAR. Please see RPS Security Document [21] for details.<AS2> Figure 17: filter-set objects. Thepurpose of an hierarchical set namefilter attribute defines the set's policy filter. A policy filter is a logical expression which when applied topartition thea setname space so that the controllersofthe set name X1 controls the whole set name space under X1, i.e. X1:...:Xn-1. This is important since anyone can createroutes returns aset named AS-MCI-CUSTOMERS but only the people created AS3561 can create AS3561:AS-CUSTOMERS. Insubset of these routes. We say that theformer, it is not clear ifpolicy filter matches theset AS-MCI-CUSTOMERS hassubset returned. The policy filter can match routes using anyrelationship with MCI. InBGP path attribute, such as thelatter, wedestination address prefix (or NLRI), AS-path, or community attributes. The policy filters canguarantee that AS3561:AS-CUSTOMERS and AS3561 are createdbe composite bythe same entity. 6 aut-num Class Routing policies are specifiedusing theaut-num class.operators AND, OR, and NOT. Theattributesfollowing policy filters can be used to select a subset ofthe aut-num class are shown in Figure 16.routes: ANY Thevaluekeyword ANY matches all routes. Address-Prefix Set This is an explicit list of address prefixes enclosed in braces '{' and '}'. The policy filter matches theaut-num attributeset of routes whose destination address-prefix is in theAS number of the AS describedset. For example: { 0.0.0.0/0 } { 128.9.0.0/16, 128.8.0.0/16, 128.7.128.0/17, 5.0.0.0/8 } { } An address prefix can be optionally followed bythis object. The as-name attribute isasymbolic name (in RPSL name syntax)range operator (i.e. '^-', '^+', '^n', or '^n-m'). For example, the set { 5.0.0.0/8^+, 128.9.0.0/16^-, 30.0.0.0/8^16, 30.0.0.0/8^24-32 } contains all the more specifics of 5.0.0.0/8 including 5.0.0.0/8, all the more specifics of 128.9.0.0/16 excluding 128.9.0.0/16, all theAS. The import, exportmore specifics of 30.0.0.0/8 which are of length 16 such as 30.9.0.0/16, anddefault routing policiesall the more specifics of 30.0.0.0/8 which are of length 24 to 32 such as 30.9.9.96/28. Route Set Name A route set name matches theASset of routes that arespecified using import, exportmembers of the set. A route set name may be a name of a route-set object, an AS number, or a name of an as-set object (AS numbers anddefault attributes respectively.as-set names Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page17]19] Internet Draft RPSLJanuary 15,February 10, 1999Attribute Value Type aut-num <as-number> mandatory, single-valued, class key as-name <object-name> mandatory, single-valued member-of list of <as-set-names> optional, multi-valued import see Section 6.1 optional, multi valued export see Section 6.2 optional, multi valued defaultimplicitly define route sets; please see Section6.5 optional, multi valued Figure 16: aut-num Class Attributes 6.1 import Attribute: Import Policy Specification ---------------------- ---------------------- | 7.7.7.1 |-------| |-------| 7.7.7.2 | | | ======== | | |5.3). For example: aut-num: AS1| EX1 |-------| 7.7.7.3import: from AS2| | | | | | 9.9.9.1 |------ ------| 9.9.9.2 | ---------------------- | | ---------------------- =========== | EX2 ---------------------- | | 9.9.9.3 |--------- | | | AS3 | ---------------------- Figure 17: Example topology consisting of three ASes, AS1, AS2, and AS3; two exchange points, EX1 and EX2; and six routers. Figure 17 shows a typical interconnection of ASes that we willaccept AS2 import: from AS2 accept AS-FOO import: from AS2 accept RS-FOO The keyword PeerAS can beusing in our examples throughout this section. In this example topology, there are three ASes, AS1, AS2, and AS3; two exchange points, EX1 and EX2; and six routers. Routers connected toused instead of thesame exchange point peer with each other and exchange routing information. Each router would export a subsetAS number of theroutes it has to itspeerrouters. Peer routers would import a subset of these routes. A router while importing routes would set some route attributes.AS. PeerAS is particularly useful when the peering is specified using an AS expression. Forexample,example: as-set: AS-FOO members: AS2, AS3 aut-num: AS1can assign higher preference values to the routes it importsimport: from AS-FOO accept PeerAS is same as: aut-num: AS1 import: from AS2so that it prefersaccept AS2over AS3. While exporting routes, a router may also set some route attributes in order to affectimport: from AS3 accept AS3 A routeselection of other ASes. For example, AS2 maysetthe MULTI-EXIT-DISCRIMINATOR BGP attribute so that AS1 prefers the routes through router 9.9.9.2. Most interAS policies are specified by specifying what route subsetsname can also beimported or exported, and howfollowed by one of thevarious BGP Alaettinoglu et. al. Expires July 15, 1999 [Page 18] Internet Draft RPSL January 15, 1999 route attributesoperators '^-', '^+', '^n' or '^n-m'. These operators aresetdistributive over the route sets. For example, { 5.0.0.0/8, 6.0.0.0/8 }^+ equals { 5.0.0.0/8^+, 6.0.0.0/8^+ }, andused. In RPSL, an import policy is divided into import policy expressions. Each import policyAS1^- equals all the exclusive more specifics of routes originated by AS1. AS Path Regular Expressions An AS-path regular expressionis specified using an import attribute. The import attribute hascan be used as a policy filter by enclosing thefollowing syntax (we will extend this syntax laterexpression inSections 6.3`<' and6.6): import: from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter> The action specification is optional. The semantics of an import attribute is as follows:`>'. An AS-path policy filter matches the set of routesthat arewhich traverses a sequence of ASes matched by<filter> are imported from allthepeersAS-path regular expression. A router can check this using the AS_PATH attribute in<peerings>; while importing routes at <peering-M>, <action-M> is executed. E.g. aut-num: AS1 import: from AS2 action pref = 1; accept { 128.9.0.0/16 } This example states thattheroute 128.9.0.0/16 is accepted from AS2 with preference 1. InBorder Gateway Protocol [20], or thenext few subsections, we will describe how peerings, actions and filtersRD_PATH attribute in the Inter-Domain Routing Protocol[19]. AS-path Regular Expressions arespecified. 6.1.1 Peering Specification Our example above used anPOSIX compliant regular expressions over the alphabet of ASnumber to specify peerings. The peerings can be specified at different granularities.numbers. Thesyntax of a peering specification has two forms. The first one isregular expression constructs are as follows:<peer-as> [<peer-router>] [at <local-router>]ASN where<local-router> and <peer-router> are IP addresses of routers, <peer-as>ASN is an AS number.<peer-as> mustASN matches the AS-path that is of length 1 and contains the corresponding AS number (e.g. AS-path regular expression AS1 matches the AS-path ``1''). The keyword PeerAS can be used instead of the AS number of<peer-router>. Both <local-router> and <peer-router> are optional. If neither routerthe Alaettinoglu et. al. Expires August 10, 1999 [Page 20] Internet Draft RPSL February 10, 1999 peer AS. AS-set where AS-set isspecified, this peering specification identifies allan AS set name. AS-set matches thepeerings betweenAS-paths that is matched by one of thelocalASes in the AS-set. . matches the AS-paths matched by any ASandnumber. [...] is an AS number set. It matches the<peer-as>. If both <local-router> and <peer-router> are specified, only that particular peeringAS-paths matched by the AS numbers listed betweenthese two routersthe brackets. The AS numbers in the set areidentified.separated by white space characters. Ifonly the <local-router>a `-' isspecified,used between two AS numbers in this set, allpeeringsAS numbers between the<local-router> and any router in <peer-as>two AS numbers areidentified. If onlyincluded in the<peer-router>set. If an as-set name isspecified,listed, allpeerings from the routersAS numbers in thelocalas-set are included. [^...] is a complemented AStonumber set. It matches any AS-path which is not matched by the<peer-router> are identified. Alaettinoglu et. al. Expires July 15, 1999 [Page 19] Internet Draft RPSL January 15, 1999 We next give examples. ConsiderAS numbers in thetopologyset. ^ Matches the empty string at the beginning ofFigure 17 where 7.7.7.1, 7.7.7.2 and 7.7.7.3 peer with each other; 9.9.9.1, 9.9.9.2 and 9.9.9.3 peer with each other. Inan AS-path. $ Matches thefollowing example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2. (1) aut-num: AS1 import: from AS2 7.7.7.2empty string at7.7.7.1 accept { 128.9.0.0/16 } Inthefollowing example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3. (2) aut-num:end of an AS-path. We next list the regular expression operators in the decreasing order of evaluation. These operators are left associative, i.e. performed left to right. Unary postfix operators * + ? {m} {m,n} {m,} For a regular expression A, A* matches zero or more occurrences of A; A+ matches one or more occurrences of A; A? matches zero or one occurrence of A; A{m} matches m occurrence of A; A{m,n} matches m to n occurrence of A; A{m,} matches m or more occurrence of A. For example, [AS1 AS2]{2} matches AS1import: fromAS1, AS1 AS2, AS2at 7.7.7.1 accept { 128.9.0.0/16 } In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3,AS1, and9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2. (3) aut-num: AS1 import: fromAS2accept { 128.9.0.0/16 } The second formAS2. Unary postfix operators ~* ~+ ~{m} ~{m,n} ~{m,} These operators have similar functionality as the correspond- ing operators listed above, but all occurrences of<peering> specificationthe regular expression has to match thefollowing syntax: <as-expression> [<router-expression-1>] [at <router-expression-2>] where <as-expression>same pattern. For example, [AS1 AS2]~{2} matches AS1 AS1 and AS2 AS2, but it does not match AS1 AS2 and AS2 AS1. Binary catenation operator This is anexpression over AS numbers and sets using operators AND, OR,implicit operator andNOT, and <router-expression-1> and <router- expression-2> areexists between two regular expressionsover router IP addresses and DNS names using operators AND, OR,A andNOT. The DNS name can only be used if thereB when no other explicit operator is specified. The resulting expression A B matches aninet-rtr object for that name that binds the name to IP addresses. This form identifies all the peerings between any local router in <router-expression-2> to anyAS-path if A matches some prefix oftheir peer routers in <router-expression-1> intheASes in <as-expression>. If <router-expression-2> is not specified, it defaults to all routers ofAS-path and B matches thelocal AS that peer with ASes in <as-expression>. If <router-expression-1> is not specified, it defaults to all routersrest of thepeer ASes in <as-expression> that peer with the local AS. In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2AS-path. Binary alternative (or) operator | For a regular expressions A and9.9.9.3. (4) as-set: AS-FOO members: AS2, AS3B, A | B matches any AS-path Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page20]21] Internet Draft RPSLJanuary 15,February 10, 1999aut-num: AS1 import: from AS-FOO at 9.9.9.1 accept { 128.9.0.0/16 } Inthat is matched by A or B. Parenthesis can be used to override the default order of evaluation. White spaces can be used to increase readability. The following are examples of AS-path filters: <AS3> <^AS1> <AS2$> <^AS1 AS2 AS3$> <^AS1 .* AS2$>. The first example9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 and 9.9.9.3, and 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2matches any route whose AS-path contains AS3, the second matches routes whose AS-path starts with AS1, the third matches routes whose AS-path ends with AS2, the fourth matches routes whose AS-path is exactly ``1 2 3'', and7.7.7.3. (5) aut-num: AS1 import: from AS-FOO accept { 128.9.0.0/16 } Inthefollowing example AS1 imports 128.9.0.0/16 from AS3 at router 9.9.9.1 (6) aut-num:fifth matches routes whose AS-path starts with AS1import: from AS-FOOandnotends in AS2atwith any number of AS numbers in between. Composite Policy Filters The following operators (in decreasing order of evaluation) can be used to form composite policy filters: NOT Given a policy filter x, NOT x matches the set of routes that are not7.7.7.1 accept { 128.9.0.0/16 } Thismatched by x. That isbecause "AS-FOOit is the negation of policy filter x. AND Given two policy filters x andnot AS2" equals AS3y, x AND y matches the intersection of the routes that are matched by x and"not 7.7.7.1" equals 9.9.9.1. 6.1.2 Action Specification Policy actions in RPSL either set or modify route attributes, such as assigning a preference to a route, adding a BGP communitythat are matched by y. OR Given two policy filters x and y, x OR y matches the union of the routes that are matched by x and that are matched by y. Note that an OR operator can be implicit, that is `x y' is equivalent to `x OR y'. E.g. NOT {128.9.0.0/16, 128.8.0.0/16} AS226 AS227 OR AS228 AS226 AND NOT {128.9.0.0/16} AS226 AND {0.0.0.0/0^0-18} The first example matches any route except 128.9.0.0/16 and 128.8.0.0/16. The second example matches theBGP community path attribute, or settingroutes of AS226, AS227 and AS228. The third example matches theMULTI-EXIT-DISCRIMINATOR attribute.routes of AS226 except 128.9.0.0/16. The fourth example Alaettinoglu et. al. Expires August 10, 1999 [Page 22] Internet Draft RPSL February 10, 1999 matches the routes of AS226 whose length are not longer than 18. Routing PolicyactionsAttributes Policy filters can alsoinstruct routers to perform special operations, such as route flap damping.use the values of other attributes for comparison. Therouting policyattributes whose values can bemodifiedused in policyactionsfilters are specified in the RPSL dictionary. Please refer to Section 7 fora list of these attributes. Each action in RPSL is terminated by the semicolon character (';'). It is possible to form composite policy actions by listing them one after the other. In a composite policy action,details. An example using theactions are executed left to right. For example, aut-num: AS1 import: from AS2 action pref = 10; med = 0; community.append(10250, 3561:10); accept { 128.9.0.0/16 } sets pref to 10, med to 0, and then appends 10250 and 3561:10 tothe BGP communitypath attribute. The prefattribute is shown below: aut-num: AS1 export: to AS2 announce AS1 AND NOT community(NO_EXPORT) Filters using theinverse of the local-pref attribute (i.e. local-pref == 65535 - pref). A route with a Alaettinoglu et. al. Expires July 15, 1999 [Page 21] Internet Draft RPSL January 15, 1999 local-pref attribute is always preferred over a route without one. 6.1.3 Filter Specification Arouting policyfilter is a logical expression which when applied to aattributes defined in the dictionary are evaluated before evaluating the operators AND, OR and NOT. Filter Set Name A filter set name matches the set of routesreturns a subset of these routes. We saythatthe policyare matched by its filtermatchesattribute. Note that thesubset returned. The policyfilter attribute of a filter set, canmatchrecursively refer to other filter set names. For example in Figure 17, fltr-foo matches { 5.0.0.0/8, 6.0.0.0/8 }, and fltr-bar matches AS1'S routesusing any path attribute, suchor { 5.0.0.0/8, 6.0.0.0/8 } if their as path contained AS2. 5.5 rtr-set Class The attributes of thedestination address prefix (or NLRI), AS-path, or community attributes.rtr-set class are shown in Figure 18. Thepolicy filters can be composite by usingrtr-set attribute defines theoperators AND, OR, and NOT.name of the set. It is an RPSL name that starts with ``rtrs-''. Thefollowing policy filters can be used to select a subsetmembers attribute lists the members ofroutes: ANYthe set. Thefilter-keyword ANY matches all routes. Address-Prefix Set Thismembers attribute isan explicita list ofaddress prefixes enclosed in braces '{'inet-rtr names, ipv4_addresses or other rtr-set names. Attribute Value Type rtr-set <object-name> mandatory, single-valued, class key members list of <inet-rtr-names> or optional, multi-valued <rtr-set-names> or <ipv4_addresses> mbrs-by-ref list of <mntner-names> optional, multi-valued Figure 18: rtr-set Class Attributes Figure 19 presents two rtr-set objects. The set rtrs-foo contains two routers, namely rtr1.isp.net and'}'.rtr2.isp.net. Thepolicy filter matches theset rtrs-bar contains the members ofroutes whose destination address-prefix is intheset. For example: { 0.0.0.0/0 } { 128.9.0.0/16, 128.8.0.0/16, 128.7.128.0/17, 5.0.0.0/8 } { } An address prefix can be optionally followed byset rtrs-foo and rtr3.isp.net, that is it contains rtr1.isp.net, rtr2.isp.net, rtr3.isp.net. Alaettinoglu et. al. Expires August 10, 1999 [Page 23] Internet Draft RPSL February 10, 1999 rtr-set: rtrs-foo rtr-set: rtrs-bar members: rtr1.isp.net, rtr2.isp.net members: rtr3.isp.net, rtrs-foo Figure 19: rtr-set objects. The mbrs-by-ref attribute is arange operator (i.e. '^-', '^+', '^n', or '^n-m'). For example, the set { 5.0.0.0/8^+, 128.9.0.0/16^-, 30.0.0.0/8^16, 30.0.0.0/8^24-32 } contains all the more specificslist of5.0.0.0/8 including 5.0.0.0/8, allmaintainer names or themore specifics of 128.9.0.0/16 excluding 128.9.0.0/16, allkeyword ANY. If this attribute is used, themore specifics of 30.0.0.0/8 whichrouter set also includes routers whose inet-rtr objects are registered by one oflength 16 such as 30.9.0.0/16,these maintainers andallwhose member-of attribute refers to themore specificsname of30.0.0.0/8 which arethis router set. If the value oflength 24a mbrs-by-ref attribute is ANY, any inet-rtr object referring to32 such as 30.9.9.96/28. Route Set Name A route set name matchesthe router set is a member ofroutes thatthe set. If the mbrs-by-ref attribute is missing, only the routers listed in the members attribute are members of the set.A routertr-set: rtrs-foo members: rtr1.isp.net, rtr2.isp.net mbrs-by-ref: MNTR-ME inet-rtr: rtr3.isp.net local-as: as1 ifaddr: 1.1.1.1 masklen 30 member-of: rtrs-foo mnt-by: MNTR-ME Figure 20: rtr-set objects. Figure 20 presents an example rtr-set object that uses the mbrs-by-ref attribute. The setname may be a namertrs-foo contains rtr1.isp.net, rtr2.isp.net and rtr3.isp.net. 5.6 Peerings and peering-set Class The attributes of the peering-set class are shown in Figure 21. A peering-set object defines aroute-set object, an AS number, or aset of peerings that are listed in its peering attributes. The peering-set attribute defines the name of the set. It is anas-set object (AS numbers and as-set names implicitly define route sets; please see Section 5.3). For example: aut-num: AS1 import: from AS2 action pref = 1; accept AS2RPSL name that starts with ``prng-''. Attribute Value Type peering-set <object-name> mandatory, single-valued, class key peering <peering> mandatory, multi-valued Figure 21: filter Class Attributes The peering attribute defines a peering that can be used for importing or Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page22]24] Internet Draft RPSLJanuary 15,February 10, 1999import: from AS2 action pref = 1; accept AS-FOO import: from AS2 action pref = 1; accept RS-FOO The keyword PeerAS can be used instead of the AS number of the peer AS. PeerAS is particularly useful when the peering is specified using an AS expression. For example: as-set: AS-FOO members: AS2, AS3 aut-num: AS1 import: from AS-FOO action pref = 1; accept PeerAS is same as: aut-num:---------------------- ---------------------- | 7.7.7.1 |-------| |-------| 7.7.7.2 | | | ======== | | | AS1import: from AS2 action pref = 1; accept| EX1 |-------| 7.7.7.3 AS2import: from AS3 action pref = 1; accept| | | | | | 9.9.9.1 |------ ------| 9.9.9.2 | ---------------------- | | ---------------------- =========== | EX2 ---------------------- | | 9.9.9.3 |--------- | | | AS3A route set name can also be followed by one| ---------------------- Figure 22: Example topology consisting of three ASes, AS1, AS2, and AS3; two exchange points, EX1 and EX2; and six routers. exporting routes. In describing peerings, we are going to use theoperators '^-', '^+', '^n' or '^n-m'. These operatorstopology of Figure 22. In this topology, there aredistributive overthree ASes, AS1, AS2, and AS3; two exchange points, EX1 and EX2; and six routers. Routers connected to theroute sets. For example, { 5.0.0.0/8, 6.0.0.0/8 }^+ equals { 5.0.0.0/8^+, 6.0.0.0/8^+ },same exchange point peer with each other and exchange routing information. That is, 7.7.7.1, 7.7.7.2 andAS1^- equals all the exclusive more specifics7.7.7.3 peer with each other; 9.9.9.1, 9.9.9.2 and 9.9.9.3 peer with each other. The syntax ofroutes originated by AS1. AS Path Regular Expressions An AS-path regular expression can be used asapolicy filter by enclosing thepeering specification is: <as-expression> [<router-expression-1>] [at <router-expression-2>] | <peering-set-name> where <as-expression> is an expressionin `<'over AS numbers and`>'. An AS-path policy filter matches the set of routes which traverses a sequence of ASes matched by the AS-path regular expression. A router can check thisAS sets usingthe AS_PATH attribute in the Border Gateway Protocol [20], or the RD_PATH attribute in the Inter-Domain Routing Protocol[19]. AS-path Regular Expressionsoperators AND, OR, and EXCEPT, and <router-expression-1> and <router-expression-2> arePOSIX compliant regularexpressions overthe alphabet of AS numbers.router IP addresses, inet-rtr names, and rtr-set names using operators AND, OR, and EXCEPT. Theregular expression constructs are as follows: ASN where ASNbinary ``EXCEPT'' operator isan AS number. ASN matchestheAS-path that is of length 1set subtraction operator andcontainshas thecorresponding AS number (e.g. AS-path regular expression AS1 matchessame precedence as theAS-path ``1''). The keyword PeerAS can be used instead ofoperator AND (it is semantically equivalent to ``AND NOT'' combination). That is ``(AS1 OR AS2) EXCEPT AS2'' equals ``AS1''. This form identifies all theAS numberpeerings between any local router in <router-expression-2> to any ofthetheir peerAS. AS-set where AS-setrouters in <router-expression-1> in the ASes in <as-expression>. If <router-expression-2> isan AS set name. AS-set matchesnot specified, it defaults to all routers of theAS-pathslocal AS that peer with ASes in <as-expression>. If <router-expression-1> ismatched by onenot specified, it defaults to all routers of the peer ASes in <as-expression> that peer with theAS-set.Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page23]25] Internet Draft RPSLJanuary 15,February 10, 1999. matches the AS-paths matched by any AS number. [...] is an AS number set. It matches the AS-paths matched by the AS numbers listed between the brackets. The AS numbers in the set are separated by white space characters. If a `-' is used between two AS numbers in this set, all AS numbers between the two AS numbers are included in the set.local AS. Ifan as-set name is listed, all AS numbers in the as-set are included. [^...] isacomplemented AS number set. It matches any AS-path which<peering-set-name> isnot matched by the AS numbers in the set. ^ Matches the empty string at the beginning of an AS-path. $ Matches the empty string at the end of an AS-path. We next list the regular expression operators inused, thedecreasing order of evaluation. These operatorspeerings areleft associative, i.e. performed left to right. Unary postfix operators * + ? {m} {m,n} {m,} For a regular expression A, A* matches zero or more occurrences of A; A+ matches one or more occurrences of A; A? matches zero or one occurrence of A; A{m} matches m occurrence of A; A{m,n} matches m to n occurrence of A; A{m,} matches m or more occurrence of A. For example, [AS1 AS2]{2} matches AS1 AS1, AS1 AS2, AS2 AS1, and AS2 AS2. Unary postfix operators ~* ~+ ~{m} ~{m,n} ~{m,} These operators have similar functionality as the correspond- ing operatorslistedabove, but all occurrencesin the corresponding peering-set object. Note that the peering-set objects can be recursive. Many special forms of this general peering specification is possible. The following examples illustrate theregular expression has to matchmost common cases, using thesame pattern. For example, [AS1 AS2]~{2} matches AS1 AS1 and AS2 AS2, but it does not matchimport attribute of the aut-num class. In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2. (1) aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 accept { 128.9.0.0/16 } In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3. (2) aut-num: AS1 import: from AS2AS1. Binary catenation operator This is an implicit operatorat 7.7.7.1 accept { 128.9.0.0/16 } In the following example 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 andexists between two regular expressions A7.7.7.3, andB when no other explicit operator is specified. The resulting expression A B matches an AS-path if A matches some prefix of9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2. (3) aut-num: AS1 import: from AS2 accept { 128.9.0.0/16 } In theAS-pathfollowing example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 andB matches the rest of9.9.9.3. (4) as-set: AS-FOO members: AS2, AS3 aut-num: AS1 import: from AS-FOO at 9.9.9.1 accept { 128.9.0.0/16 } In theAS-path. Binary alternative (or) operator | For a regular expressions Afollowing example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 andB, A | B matches any AS-path that is matched by A or B. Parenthesis can be used to override the default order of evaluation. White spaces can be used to increase readability.9.9.9.3, and 7.7.7.1 imports 128.9.0.0/16 from 7.7.7.2 and 7.7.7.3. (5) aut-num: AS1 import: from AS-FOO accept { 128.9.0.0/16 } In the following example AS1 imports 128.9.0.0/16 from AS3 at router 9.9.9.1 Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page24]26] Internet Draft RPSLJanuary 15,February 10, 1999The(6) aut-num: AS1 import: from AS-FOO and not AS2 at not 7.7.7.1 accept { 128.9.0.0/16 } This is because "AS-FOO and not AS2" equals AS3 and "not 7.7.7.1" equals 9.9.9.1. In the following example 9.9.9.1 imports 128.9.0.0/16 from 9.9.9.2 and 9.9.9.3. (7) peering-set: prng-bar peering: AS1 at 9.9.9.1 peering-set: prng-foo peering: prng-bar peering: AS2 at 9.9.9.1 aut-num: AS1 import: from prng-foo accept { 128.9.0.0/16 } 6 aut-num Class Routing policies areexamplesspecified using the aut-num class. The attributes ofAS-path filters: <AS3> <^AS1> <AS2$> <^AS1 AS2 AS3$> <^AS1 .* AS2$>.the aut-num class are shown in Figure 23. Thefirst example matches any route whose AS-path contains AS3,value of thesecond matches routes whose AS-path starts with AS1,aut-num attribute is thethird matches routes whose AS-path ends with AS2,AS number of thefourth matches routes whose AS-pathAS described by this object. The as-name attribute isexactly ``1 2 3'', anda symbolic name (in RPSL name syntax) of thefifth matches routes whose AS-path starts with AS1AS. The import, export andends in AS2 with any numberdefault routing policies of the ASnumbers in between. Compositeare specified using import, export and default attributes respectively. Attribute Value Type aut-num <as-number> mandatory, single-valued, class key as-name <object-name> mandatory, single-valued member-of list of <as-set-names> optional, multi-valued import see Section 6.1 optional, multi valued export see Section 6.2 optional, multi valued default see Section 6.5 optional, multi valued Figure 23: aut-num Class Attributes Alaettinoglu et. al. Expires August 10, 1999 [Page 27] Internet Draft RPSL February 10, 1999 6.1 import Attribute: Import PolicyFilters The following operators (in decreasing order of evaluation) can be used to form composite policy filters: NOT Given aSpecification In RPSL, an import policyfilter x, NOT x matches the set of routes that are not matched by x. That is itisthe negation ofdivided into import policyfilter x. AND Given twoexpressions. Each import policyfilters x and y, x AND y matchesexpression is specified using an import attribute. The import attribute has theintersectionfollowing syntax (we will extend this syntax later in Sections 6.3 and 6.6): import: from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter> The action specification is optional. The semantics of an import attribute is as follows: the set of routes that are matched byx and that<filter> arematched by y. OR Given two policy filters x and y, x OR y matches the union ofimported from all the peers in <peerings>; while importing routesthat are matched by x and that are matched by y. Note that an OR operator can be implicit, that is `x y'at <peering-M>, <action-M> isequivalent to `x OR y'.executed. E.g.NOT {128.9.0.0/16, 128.8.0.0/16} AS226 AS227 OR AS228 AS226 AND NOT {128.9.0.0/16} AS226 AND {0.0.0.0/0^0-18} The first example matches any route except 128.9.0.0/16 and 128.8.0.0/16. The second example matches the routes of AS226, AS227 and AS228. The third example matches the routes of AS226 except 128.9.0.0/16. The fourthaut-num: AS1 import: from AS2 action pref = 1; accept { 128.9.0.0/16 } This examplematchesstates that theroutes of AS226 whose lengthroute 128.9.0.0/16 is accepted from AS2 with preference 1. We already presented how peerings (see Section 5.6) and filters (see Section 5.4) arenot longer than 18. Routingspecified. We next present how to specify actions. 6.1.1 Action Specification PolicyAttributesactions in RPSL either set or modify route attributes, such as assigning a preference to a route, adding a BGP community to the BGP community path attribute, or setting the MULTI-EXIT-DISCRIMINATOR attribute. Policyfiltersactions can alsouse the values of other attributes for comparison.instruct routers to perform special operations, such as route flap damping. The routing policy attributes whose values can beusedmodified in policyfiltersactions are specified in the RPSL dictionary. Please refer to Section 7 for a list of these attributes. Each action in RPSL is terminated by the semicolon character (';'). It is possible to form composite policy actions by listing them one after the other. In a composite policy action, the actions are executed left to right. For example, aut-num: AS1 import: from AS2 Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page25]28] Internet Draft RPSLJanuary 15,February 10, 1999Section 7 for details. An example using theaction pref = 10; med = 0; community.append(10250, 3561:10); accept { 128.9.0.0/16 } sets pref to 10, med to 0, and then appends 10250 and 3561:10 to the BGP community path attribute. The pref attribute isshown below: aut-num: AS1 export: to AS2 announce AS1 AND NOT community.contains(NO_EXPORT) Filters using the routing policy attributes defined inthedictionary are evaluated before evaluatinginverse of theoperators AND, OR and NOT. 6.1.4 Example Policy Expressionslocal-pref attribute (i.e. local-pref == 65535 - pref). A route with a local-pref attribute is always preferred over a route without one. aut-num: AS1 import: from AS2 action pref = 1; from AS3 action pref = 2; accept AS4 The above example states that AS4's routes are accepted from AS2 with preference 1, and from AS3 with preference 2 (routes with lower integer preference values are preferred over routes with higher integer preference values). aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; from AS2 action pref = 2; accept AS4 The above example states that AS4's routes are accepted from AS2 on peering 7.7.7.1-7.7.7.2 with preference 1, and on any other peering with AS2 with preference 2. 6.2 export Attribute: Export Policy Specification Similarly, an export policy expression is specified using an export attribute. The export attribute has the following syntax: export: to <peering-1> [action <action-1>] . . . to <peering-N> [action <action-N>] announce <filter>Alaettinoglu et. al. Expires July 15, 1999 [Page 26] Internet Draft RPSL January 15, 1999The action specification is optional. The semantics of an export attribute is as follows: the set of routes that are matched by <filter> are exported to all the peers specified in <peerings>; while exporting routes at <peering-M>, <action-M> is executed. Alaettinoglu et. al. Expires August 10, 1999 [Page 29] Internet Draft RPSL February 10, 1999 E.g. aut-num: AS1 export: to AS2 action med = 5; community .= { 70 }; announce AS4 In this example, AS4's routes are announced to AS2 with the med attribute's value set to 5 and community 70 added to the community list. Example: aut-num: AS1 export: to AS-FOO announce ANY In this example, AS1 announces all of its routes to the ASes in the set AS-FOO. 6.3 Other Routing Protocols, Multi-Protocol Routing Protocols, and Injecting Routes Between Protocols The more complete syntax of the import and export attributes are as follows: import: [protocol <protocol-1>] [into <protocol-2>] from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter> export: [protocol <protocol-1>] [into <protocol-2>] to <peering-1> [action <action-1>] . . . to <peering-N> [action <action-N>] announce <filter> Where the optional protocol specifications can be used for specifying policies for other routing protocols, or for injecting routes of one protocol into another protocol, or for multi-protocol routing policies. The valid protocol names are defined in the dictionary. The <protocol-1> is the name of the protocol whose routes are being exchanged. TheAlaettinoglu et. al. Expires July 15, 1999 [Page 27] Internet Draft RPSL January 15, 1999<protocol-2> is the name of the protocol which is receiving these routes. Both <protocol-1> and <protocol-2> default to the Internet Exterior Gateway Protocol, currently BGP. In the following example, all interAS routes are injected into RIP. Alaettinoglu et. al. Expires August 10, 1999 [Page 30] Internet Draft RPSL February 10, 1999 aut-num: AS1 import: from AS2 accept AS2 export: protocol BGP4 into RIP to AS1 announce ANY In the following example, AS1 accepts AS2's routes including any more specifics of AS2's routes, but does not inject these extra more specific routes into OSPF. aut-num: AS1 import: from AS2 accept AS2^+ export: protocol BGP4 into OSPF to AS1 announce AS2 In the following example, AS1 injects its static routes (routes which are members of the set AS1:RS-STATIC-ROUTES) to the interAS routing protocol and appends AS1 twice to their AS paths. aut-num: AS1 import: protocol STATIC into BGP4 from AS1 action aspath.prepend(AS1, AS1); accept AS1:RS-STATIC-ROUTES In the following example, AS1 imports different set of unicast routes for multicast reverse path forwarding from AS2: aut-num: AS1 import: from AS2 accept AS2 import: protocol IDMR from AS2 accept AS2:RS-RPF-ROUTES 6.4 Ambiguity Resolution It is possible that the same peering can be covered by more that one peering specification in a policy expression. For example:Alaettinoglu et. al. Expires July 15, 1999 [Page 28] Internet Draft RPSL January 15, 1999aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 2; from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; accept AS4 Alaettinoglu et. al. Expires August 10, 1999 [Page 31] Internet Draft RPSL February 10, 1999 This is not an error, though definitely not desirable. To break the ambiguity, the action corresponding to the first peering specification is used. That is the routes are accepted with preference 2. We call this rule as the specification-order rule. Consider the example: aut-num: AS1 import: from AS2 action pref = 2; from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5; accept AS4 where both peering specifications cover the peering 7.7.7.1-7.7.7.2, though the second one covers it more specifically. The specification order rule still applies, and only the action ``pref = 2'' is executed. In fact, the second peering-action pair has no use since the first peering-action pair always covers it. If the intended policy was to accept these routes with preference 1 on this particular peering and with preference 2 in all other peerings, the user should have specified: aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 1; dpa = 5; from AS2 action pref = 2; accept AS4 It is also possible that more than one policy expression can cover the same set of routes for the same peering. For example: aut-num: AS1 import: from AS2 action pref = 2; accept AS4 import: from AS2 action pref = 1; accept AS4 In this case, the specification-order rule is still used. That is, AS4's routes are accepted from AS2 with preference 2. If the filters were overlapping but not exactly the same: aut-num: AS1 import: from AS2 action pref = 2; accept AS4Alaettinoglu et. al. Expires July 15, 1999 [Page 29] Internet Draft RPSL January 15, 1999import: from AS2 action pref = 1; accept AS4 OR AS5 the AS4's routes are accepted from AS2 with preference 2 and however AS5's routes are also accepted, but with preference 1. Alaettinoglu et. al. Expires August 10, 1999 [Page 32] Internet Draft RPSL February 10, 1999 We next give the general specification order rule for the benefit of the RPSL implementors. Consider two policy expressions: aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-2 action action-2 accept filter-2 The above policy expressions are equivalent to the following three expressions where there is no ambiguity: aut-num: AS1 import: from peerings-1 action action-1 accept filter-1 import: from peerings-3 action action-2 accept filter-2 AND NOT filter-1 import: from peerings-4 action action-2 accept filter-2 where peerings-3 are those that are covered by both peerings-1 and peerings-2, and peerings-4 are those that are covered by peerings-2 but not by peerings-1 (``filter-2 AND NOT filter-1'' matches the routes that are matched by filter-2 but not by filter-1). Example: aut-num: AS1 import: from AS2 7.7.7.2 at 7.7.7.1 action pref = 2; accept {128.9.0.0/16} import: from AS2 action pref = 1; accept {128.9.0.0/16, 75.0.0.0/8} Lets consider two peerings with AS2, 7.7.7.1-7.7.7.2 and 9.9.9.1-9.9.9.2. Both policy expressions cover 7.7.7.1-7.7.7.2. On this peering, the route 128.9.0.0/16 is accepted with preference 2, and the route 75.0.0.0/8 is accepted with preference 1. The peering 9.9.9.1-9.9.9.2 is only covered by the second policy expressions. Hence, both the route 128.9.0.0/16 and the route 75.0.0.0/8 are accepted with preference 1 on peering 9.9.9.1-9.9.9.2. Note that the same ambiguity resolution rules also apply to export and default policy expressions. Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page30]33] Internet Draft RPSLJanuary 15,February 10, 1999 6.5 default Attribute: Default Policy Specification Default routing policies are specified using the default attribute. The default attribute has the following syntax: default: to <peering> [action <action>] [networks <filter>] The <action> and <filter> specifications are optional. The semantics are as follows: The <peering> specification indicates the AS (and the router if present) is being defaulted to; the <action> specification, if present, indicates various attributes of defaulting, for example a relative preference if multiple defaults are specified; and the <filter> specifications, if present, is a policy filter. A routerchooses aonly uses the defaultrouter frompolicy if it received the routesin its routing table that matchesmatched by <filter> from this<filter>.peer. In the following example, AS1 defaults to AS2 for routing. aut-num: AS1 default: to AS2 In the following example, router 7.7.7.1 in AS1 defaults to router 7.7.7.2 in AS2. aut-num: AS1 default: to AS2 7.7.7.2 at 7.7.7.1 In the following example, AS1 defaults to AS2 and AS3, but prefers AS2 over AS3. aut-num: AS1 default: to AS2 action pref = 1; default: to AS3 action pref = 2; In the following example, AS1 defaults to AS2 and uses 128.9.0.0/16 as the default network. aut-num: AS1 default: to AS2 networks { 128.9.0.0/16 } Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page31]34] Internet Draft RPSLJanuary 15,February 10, 1999 6.6 Structured Policy Specification The import and export policies can be structured. We only reccomend structured policies to advanced RPSL users. Please feel free to skip this section. The syntax for a structured policy specification is the following: <import-factor> ::= from <peering-1> [action <action-1>] . . . from <peering-N> [action <action-N>] accept <filter>; <import-term> ::= <import-factor> | LEFT-BRACE <import-factor> . . . <import-factor> RIGHT-BRACE <import-expression> ::= <import-term> | <import-term> EXCEPT <import-expression> | <import-term> REFINE <import-expression> import: [protocol <protocol1>] [into <protocol2>] <import-expression> Please note the semicolon at the end of an <import-factor>. If the policy specification is not structured (as in all the examples in other sections), this semicolon is optional. The syntax and semantics for an <import-factor> is already defined in Section 6.1. An <import-term> is either a sequence of <import-factor>'s enclosed within matching braces (i.e. `{' and `}') or just a single <import-factor>. The semantics of an <import-term> is the union of <import-factor>'s using the specification order rule. An <import-expression> is either a single <import-term> or an <import-term> followed by one of the keywords "except" and "refine", followed by another <import-expression>. Note that our definition allows nested expressions. Hence there can be exceptions to exceptions, refinements to refinements, or even refinements to exceptions, and so on. The semantics for the except operator is as follows: The result of an except operation is another <import-term>. The resulting policy set contains the policies of the right hand side but their filters are modified to only include the routes also matched by the left hand side. The policies of the left hand side are included afterwards and their filters are modified to exclude the routes matched by the right hand side. Please note that Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page32]35] Internet Draft RPSLJanuary 15,February 10, 1999 the filters are modified during this process but the actions are copied verbatim. When there are multiple levels of nesting, the operations (both except and refine) are performed right to left. Consider the following example: import: from AS1 action pref = 1; accept as-foo; except { from AS2 action pref = 2; accept AS226; except { from AS3 action pref = 3; accept {128.9.0.0/16}; } } where the route 128.9.0.0/16 is originated by AS226, and AS226 is a member of the as set as-foo. In this example, the route 128.9.0.0/16 is accepted from AS3, any other route (not 128.9.0.0/16) originated by AS226 is accepted from AS2, and any other ASes' routes in as-foo is accepted from AS1. We can come to the same conclusion using the algebra defined above. Consider the inner exception specification: from AS2 action pref = 2; accept AS226; except { from AS3 action pref = 3; accept {128.9.0.0/16}; } is equivalent to { from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; } Hence, the original expression is equivalent to: import: from AS1 action pref = 1; accept as-foo; except { from AS3 action pref = 3; accept AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; } which is equivalent to Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page33]36] Internet Draft RPSLJanuary 15,February 10, 1999 import: { from AS3 action pref = 3; accept as-foo AND AS226 AND {128.9.0.0/16}; from AS2 action pref = 2; accept as-foo AND AS226 AND NOT {128.9.0.0/16}; from AS1 action pref = 1; accept as-foo AND NOT (AS226 AND NOT {128.9.0.0/16} OR AS226 AND {128.9.0.0/16}); } Since AS226 is in as-foo and 128.9.0.0/16 is in AS226, it simplifies to: import: { from AS3 action pref = 3; accept {128.9.0.0/16}; from AS2 action pref = 2; accept AS226 AND NOT {128.9.0.0/16}; from AS1 action pref = 1; accept as-foo AND NOT AS226; } In the case of the refine operator, the resulting set is constructed by taking the cartasian product of the two sides as follows: for each policy l in the left hand side and for each policy r in the right hand side, the peerings of the resulting policy are the peerings common to both r and l; the filter of the resulting policy is the intersection of l's filter and r's filter; and action of the resulting policy is l's action followed by r's action. If there are no common peerings, or if the intersection of filters is empty, a resulting policy is not generated. Consider the following example: import: { from AS-ANY action pref = 1; acceptcommunity.contains({3560,10});community(3560:10); from AS-ANY action pref = 2;ac- cept community.contains({3560,20});accept community(3560:20); } refine { from AS1 accept AS1; from AS2 accept AS2; from AS3 accept AS3; } Here, any route with community{3560,10}3560:10 is assigned a preference of 1 and any route with community{3560,20}3560:20 is assigned a preference of 2 regardless of whom they are imported from. However, only AS1's routes are imported from AS1, and only AS2's routes are imported from AS2, and only AS3's routes are imported form AS3, and no routes are imported from any other AS. We can reach the same conclusion using the above algebra. That is, our example is equivalent to: Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page34]37] Internet Draft RPSLJanuary 15,February 10, 1999 import: { from AS1 action pref = 1; acceptcommunity.contains({3560,10})community(3560:10) AND AS1; from AS1 action pref = 2; acceptcommunity.contains({3560,20})community(3560:20) AND AS1; from AS2 action pref = 1; acceptcommunity.contains({3560,10})community(3560:10) AND AS2; from AS2 action pref = 2; acceptcommunity.contains({3560,20})community(3560:20) AND AS2; from AS3 action pref = 1; acceptcommunity.contains({3560,10})community(3560:10) AND AS3; from AS3 action pref = 2; acceptcommunity.contains({3560,20})community(3560:20) AND AS3; } Note that the common peerings between ``from AS1'' and ``from AS-ANY'' are those peerings in ``from AS1''. Even though we do not formally define ``common peerings'', it is straight forward to deduce the definition from the definitions of peerings (please see Section6.1.1).5.6). Consider the following example: import: { from AS-ANY action med = 0; accept {0.0.0.0/0^0-18}; } refine { from AS1 at 7.7.7.1 action pref = 1; accept AS1; from AS1 action pref = 2; accept AS1; } where only routes of length 0 to 18 are accepted and med's value is set to 0 to disable med's effect for all peerings; In addition, from AS1 only AS1's routes are imported, and AS1's routes imported at 7.7.7.1 are preferred over other peerings. This is equivalent to: import: { from AS1 at 7.7.7.1 action med=0; pref=1; accept{0.0.0.0/0^0- 18}{0.0.0.0/0^0-18} AND AS1; from AS1 action med=0; pref=2; accept{0.0.0.0/0^0- 18}{0.0.0.0/0^0-18} AND AS1; } The above syntax and semantics also apply equally to structured export policies with ``from'' replaced with ``to'' and ``accept'' is replaced with ``announce''. 7 dictionary Class The dictionary class provides extensibility to RPSL. Dictionary objects define routing policy attributes, types, and routing protocols. Routing Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page35]38] Internet Draft RPSLJanuary 15,February 10, 1999 policy attributes, henceforth called rp-attributes, may correspond to actual protocol attributes, such as the BGP path attributes (e.g. community, dpa, and AS-path), or they may correspond to router features (e.g. BGP route flap damping). As new protocols, new protocol attributes, or new router features are introduced, the dictionary object is updated to include appropriate rp-attribute and protocol definitions. An rp-attribute is an abstract class; that is a data representation is not available. Instead, they are accessed through access methods. For example, the rp-attribute for the BGP AS-path attribute is called aspath; and it has an access method called prepend which stuffs extra AS numbers to the AS-path attributes. Access methods can take arguments. Arguments are strongly typed. For example, the method prepend above takes AS numbers as arguments. Once an rp-attribute is defined in the dictionary, it can be used to describe policy filters and actions. Policy analysis tools are required to fetch the dictionary object and recognize newly defined rp-attributes, types, and protocols. The analysis tools may approximate policy analyses on rp-attributes that they do not understand: a filter method may always match, and an action method may always perform no-operation. Analysis tools may even download code to perform appropriate operations using mechanisms outside the scope of RPSL. We next describe the syntax and semantics of the dictionary class. This description is not essential for understanding dictionary objects (but it is essential for creating one). Please feel free to skip to the RPSL Initial Dictionary subsection (Section 7.1). The attributes of the dictionary class are shown in Figure18.24. The dictionary attribute is the name of the dictionary object, obeying the RPSL naming rules. There can be many dictionary objects, however there is always one well-known dictionary object ``RPSL''. All tools use this dictionary by default. Attribute Value Type dictionary <object-name> mandatory, single-valued, class key rp-attribute see description in text optional, multi valued typedef see description in text optional, multi valued protocol see description in text optional, multi valued Figure18:24: dictionary Class Attributes The rp-attribute attribute has the following syntax: rp-attribute: <name> <method-1>(<type-1-1>, ..., <type-1-N1> [, "..."]) ... Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page36]39] Internet Draft RPSLJanuary 15,February 10, 1999 <method-M>(<type-M-1>, ..., <type-M-NM> [, "..."]) where <name> is the name of the rp-attribute; and <method-i> is the name of an access method for the rp-attribute, taking Ni arguments where the j-th argument is of type <type-i-j>. A method name is either an RPSL name or one of the operators defined in Figure19.25. The operator methods with the exception of operator() and operator[] can take only one argument. operator= operator== operator<<= operator< operator>>= operator> operator+= operator>= operator-= operator<= operator*= operator!= operator/= operator() operator.= operator[] Figure19:25: Operators An rp-attribute can have many methods defined for it. Some of the methods may even have the same name, in which case their arguments are of different types. If the argument list is followed by ``...'', the method takes a variable number of arguments. In this case, the actual arguments after the Nth argument are of type <type-N>. Arguments are strongly typed. A <type> in RPSL is either a predefined type, a union type, a list type, or a dictionary defined type. The predefined types are listed in Figure20.26. integer[lower, upper]as_numberipv4_address real[lower, upper]ipv4_addressaddress_prefix enum[name, name, ...]address_prefix stringaddress_prefix_rangebooleanstring dns_namerpsl_wordboolean filterfree_textrpsl_word as_set_name20:26: Predefined Types The integer and the real predefined types can be followed by a lower and an upper bound to specify the set of valid values of the argument. The range specification is optional. We use the ANSI C language conventions for representing integer, real and string values. The enum type is followed Alaettinoglu et. al. Expires August 10, 1999 [Page 40] Internet Draft RPSL February 10, 1999 by a list of RPSL names which are the valid values of the type. The boolean type can take the values true or false. as_number, ipv4_address,Alaettinoglu et. al. Expires July 15, 1999 [Page 37] Internet Draft RPSL January 15, 1999address_prefix and dns_name types are as in Section 2. filter type is a policy filter as in Section 6. The value of filter type is suggested to be enclosed in parenthesis. The syntax of a union type is as follows: union <type-1>, ... , <type-N> where <type-i> is an RPSL type. The union type is either of the types <type-1> through <type-N> (analogous to unions in C[14]). The syntax of a list type is as follows: list [<min_elems>:<max_elems>] of <type> In this case, the list elements are of <type> and the list contains at least <min_elems> and at most <max_elems> elements. The size specification is optional. If it is not specified, there is no restriction in the number of list elements. A value of a list type is represented as a sequence of elements separated by the character ``,'' and enclosed by the characters ``{'' and ``}''. The typedef attribute in the dictionary defines named types as follows: typedef: <name> <type> where <name> is a name for type <type>. typedef attribute is paticularly useful when the type defined is not a predefined type (e.g. list of unions, list of lists, etc.). A protocol attribute of the dictionary class defines a protocol and a set of peering parameters for that protocol (which are used in inet-rtr class in Section 9). Its syntax is as follows: protocol: <name> MANDATORY | OPTIONAL <parameter-1>(<type-1-1>, ...,<type-1- N1><type-1-N1> [, "..."]) ... MANDATORY | OPTIONAL <parameter-M>(<type-M-1>, ...,<type-M- NM><type-M-NM> [, "..."]) Alaettinoglu et. al. Expires August 10, 1999 [Page 41] Internet Draft RPSL February 10, 1999 where <name> is the name of the protocol; MANDATORY and OPTIONAL are keywords; and <parameter-i> is a peering parameter for this protocol, takingAlaettinoglu et. al. Expires July 15, 1999 [Page 38] Internet Draft RPSL January 15, 1999Ni many arguments. The syntax and semantics of the arguments are as in the rp-attribute. If the keyword MANDATORY is used, the parameter is mandatory and needs to be specified for each peering of this protocol. If the keyword OPTIONAL is used, the parameter can be skipped. 7.1 Initial RPSL Dictionary and Example Policy Actions and Filters dictionary: RPSL rp-attribute: # preference, smaller values represent higher preferences pref operator=(integer[0, 65535]) rp-attribute: # BGP multi_exit_discriminator attribute med # to set med to 10: med = 10; # to set med to the IGP metric: med = igp_cost; operator=(union integer[0, 65535], enum[igp_cost]) rp-attribute: # BGP destination preference attribute (dpa) dpa operator=(integer[0, 65535]) rp-attribute: # BGP aspath attribute aspath # prepends AS numbers from last to first order prepend(as_number, ...) typedef: # a community value in RPSL is either # - a 4 byte integer (ok to use 3561:70 notation) # - internet, no_export, no_advertise (see RFC-1997) community_elm union integer[1, 4294967295], enum[internet, no_export, no_advertise], typedef: # list of community values { 40, no_export, 3561:70 } community_list list of community_elm rp-attribute: # BGP community attribute community # set to a list of communities operator=(community_list) # append community values operator.=(community_list) append(community_elm, ...) # delete community values delete(community_elm, ...) # a filter: true if one of community values is contained contains(community_elm, ...) # shortcut to contains: community(no_export, 3561:70) operator()(community_elm, ...) # order independent equality comparison operator==(community_list) Alaettinoglu et. al. Expires August 10, 1999 [Page 42] Internet Draft RPSL February 10, 1999 rp-attribute: # next hop router in a static route next-hop # to set to 7.7.7.7: next-hop = 7.7.7.7;Alaettinoglu et. al. Expires July 15, 1999 [Page 39] Internet Draft RPSL January 15, 1999# to set to router's own address: next-hop = self; operator=(union ipv4_address, enum[self]) rp-attribute: # cost of a static route cost operator=(integer[0, 65535]) protocol: BGP4 # as number of the peer router MANDATORY asno(as_number) # enable flap damping OPTIONAL flap_damp() OPTIONAL flap_damp(integer[0,65535],# penalty per flap integer[0,65535],# penalty value for supression integer[0,65535],# penalty value for reuse integer[0,65535],# halflife in secs when up integer[0,65535],# halflife in secs when down integer[0,65535])# maximum penalty protocol: OSPF protocol: RIP protocol: IGRP protocol: IS-IS protocol: STATIC protocol: RIPng protocol: DVMRP protocol: PIM-DM protocol: PIM-SM protocol: CBT protocol: MOSPF Figure21:27: RPSL Dictionary Figure2127 shows the initial RPSL dictionary. It has seven rp-attributes: pref to assign local preference to the routes accepted; med to assign a value to the MULTI_EXIT_DISCRIMINATOR BGP attribute; dpa to assign a value to the DPA BGP attribute; aspath to prepend a value to the AS_PATH BGP attribute; community to assign a value to or to check the value of the community BGP attribute; next-hop to assign next hop routers to static routes; and cost to assign a cost to static routes. The dictionary defines two types: community_elm and community_list. community_elm type is either a 4-byte unsigned integer, or one of the keywords internet, no_export or no_advertise (defined in [9]). An integer can be specified using two 2-byte integers seperated by ``:'' to partition the community number space so that a provider can use its AS number as the first two bytes, and assigns a semantics of its choice to the last two bytes. The initial dictionary (Figure21)27) defines only options for the Border Gateway Protocol: asno and flap_damp. The mandatory asno option is the AS number of the peer router. The optional flap_damp option instructs the router to damp route flaps[22] when importing routes from the peer router. Alaettinoglu et. al. Expires August 10, 1999 [Page 43] Internet Draft RPSL February 10, 1999 It can be specified with or without parameters. If parameters are missing, they default to:Alaettinoglu et. al. Expires July 15, 1999 [Page 40] Internet Draft RPSL January 15, 1999flap_damp(1000, 2000, 750, 900, 900, 20000) That is, a penalty of 1000 is assigned at each route flap, the route is suppressed when penalty reaches 2000. The penalty is reduced in half after 15 minutes (900 seconds) of stability regardless of whether the route is up or down. A supressed route is reused when the penalty falls below 750. The maximum penalty a route can be assigned is 20,000 (i.e. the maximum suppress time after a route becomes stable is about 75 minutes). These parameters are consistent with the default flap damping parameters in several routers. Policy Actions and Filters Using RP-Attributes The syntax of a policy action or a filter using an rp-attribute x is as follows: x.method(arguments) x ``op'' argument where method is a method and ``op'' is an operator method of the rp-attribute x. If an operator method is used in specifying a composite policy filter, it evaluates earlier than the composite policy filter operators (i.e. AND, OR, NOT, and implicit or operator). The pref rp-attribute can be assigned a positive integer as follows: pref = 10; The med rp-attribute can be assigned either a positive integer or the word ``igp_cost'' as follows: med = 0; med = igp_cost; The dpa rp-attribute can be assigned a positive integer as follows: dpa = 100; Alaettinoglu et. al. Expires August 10, 1999 [Page 44] Internet Draft RPSL February 10, 1999 The BGP community attribute is list-valued, that is it is a list of 4-byte integers each representing a ``community''. The following examples demonstrate how to add communities to this rp-attribute:Alaettinoglu et. al. Expires July 15, 1999 [Page 41] Internet Draft RPSL January 15, 1999community .= { 100 }; community .= { NO_EXPORT }; community .= { 3561:10 }; In the last case, a 4-byte integer is constructed where the more significant two bytes equal 3561 and the less significant two bytes equal 10. The following examples demonstrate how to delete communities from the community rp-attribute: community.delete(100, NO_EXPORT, 3561:10); Filters that use the community rp-attribute can be defined as demonstrated by the following examples: community.contains(100, NO_EXPORT, 3561:10); community(100, NO_EXPORT, 3561:10); # shortcut The community rp-attribute can be set to a list of communities as follows: community = {100, NO_EXPORT, 3561:10, 200}; community = {}; In this first case, the community rp-attribute contains the communities 100, NO_EXPORT, 3561:10, and 200. In the latter case, the community rp-attribute is cleared. The community rp-attribute can be compared against a list of communities as follows: community == {100, NO_EXPORT, 3561:10, 200}; # exact match To influence the route selection, the BGP as_path rp-attribute can be made longer by prepending AS numbers to it as follows: aspath.prepend(AS1); aspath.prepend(AS1, AS1, AS1); Alaettinoglu et. al. Expires August 10, 1999 [Page 45] Internet Draft RPSL February 10, 1999 The following examples are invalid: med = -50; # -50 is not in the range med = igp; # igp is not one of the enum valuesAlaettinoglu et. al. Expires July 15, 1999 [Page 42] Internet Draft RPSL January 15, 1999med.assign(10); # method assign is not defined community.append(AS3561:20); # the first argument should be 3561 Figure2228 shows a more advanced example using the rp-attribute community. In this example, AS3561 bases its route selection preference on the community attribute. Other ASes may indirectly affect AS3561's route selection by including the appropriate communities in their route announcements. aut-num: AS1 export: to AS2 action community.={3561:90}; to AS3 action community.={3561:80}; announce AS1 as-set: AS3561:AS-PEERS members: AS2, AS3 aut-num: AS3561 import: from AS3561:AS-PEERS action pref = 10; acceptcommunity.contains(3561:90)community(3561:90) import: from AS3561:AS-PEERS action pref = 20; acceptcommunity.contains(3561:80)community(3561:80) import: from AS3561:AS-PEERS action pref = 20; acceptcommunity.contains(3561:70)community(3561:70) import: from AS3561:AS-PEERS action pref = 0; accept ANY Figure22:28: Policy example using the community rp-attribute. 8 Advanced route Class 8.1 Specifying Aggregate Routes The components, aggr-bndry, aggr-mtd, export-comps, inject, and holes attributes are used for specifying aggregate routes [11]. A route object specifies an aggregate route if any of these attributes, with the exception Alaettinoglu et. al. Expires August 10, 1999 [Page 46] Internet Draft RPSL February 10, 1999 of inject, is specified. The origin attribute for an aggregate route is the AS performing the aggregation, i.e. the aggregator AS. In this section, we used the term "aggregate" to refer to the route generated, the term "component" to refer to the routes used to generate the path attributes of the aggregate, and the term "more specifics" to refer to any route which isAlaettinoglu et. al. Expires July 15, 1999 [Page 43] Internet Draft RPSL January 15, 1999a more specific of the aggregate regardless of whether it was used to form the path attributes. The components attribute defines what component routes are used to form the aggregate. Its syntax is as follows: components: [ATOMIC] [[<filter>] [protocol <protocol> <filter> ...]] where <protocol> is a routing protocol name such as BGP4, OSPF or RIP (valid names are defined in the dictionary) and <filter> is a policy expression. The routes that match one of these filters and are learned from the corresponding protocol are used to form the aggregate. If <protocol> is omitted, it defaults to any protocol. <filter> implicitly contains an "AND" term with the more specifics of the aggregate so that only the component routes are selected. If the keyword ATOMIC is used, the aggregation is done atomically [11]. If a <filter> is not specified it defaults to more specifics. If the components attribute is missing, all more specifics without the ATOMIC keyword is used. route: 128.8.0.0/15 origin: AS1 components: <^AS2> route: 128.8.0.0/15 origin: AS1 components: protocol BGP4 {128.8.0.0/16^+} protocol OSPF {128.9.0.0/16^+} Figure23:29: Two aggregate route objects. Figure2329 shows two route objects. In the first example, more specifics of 128.8.0.0/15 with AS paths starting with AS2 are aggregated. In the second example, some routes learned from BGP and some routes learned form OSPF are aggregated. The aggr-bndry attribute is an AS expression over AS numbers and setsusing operators AND, OR, and NOT.(see Section 5.6). The result defines the set of ASes which form the aggregation boundary. If the aggr-bndry attribute is missing, the origin AS is the sole aggregation boundary. Outside the aggregation boundary, only the aggregate is exported and more specifics are suppressed. However, within the boundary, the more specifics are also exchanged. Alaettinoglu et. al. Expires August 10, 1999 [Page 47] Internet Draft RPSL February 10, 1999 The aggr-mtd attribute specifies how the aggregate is generated. Its syntax is as follow: aggr-mtd: inboundAlaettinoglu et. al. Expires July 15, 1999 [Page 44] Internet Draft RPSL January 15, 1999| outbound [<as-expression>] where <as-expression> is an expressionover AS numbers and sets using operators AND, OR,over AS numbers andNOT.sets (see Section 5.6). If <as-expression> is missing, it defaults to AS-ANY. If outbound aggregation is specified, the more specifics of the aggregate will be present within the AS and the aggregate will be formed at all inter-AS boundaries with ASes in <as-expression> before export, except for ASes that are within the aggregating boundary (i.e. aggr-bndry is enforced regardless of <as-expression>). If inbound aggregation is specified, the aggregate is formed at all inter-AS boundaries prior to importing routes into the aggregator AS. Note that <as-expression> can not be specified with inbound aggregation. If aggr-mtd attribute is missing, it defaults to "outbound AS-ANY". route: 128.8.0.0/15 route: 128.8.0.0/15 origin: AS1 origin: AS2 components: {128.8.0.0/15^-} components: {128.8.0.0/15^-} aggr-bndry: AS1 OR AS2 aggr-bndry: AS1 OR AS2 aggr-mtd: outbound AS-ANY aggr-mtd: outbound AS-ANY Figure24:30: Outbound multi-AS aggregation example. Figure2430 shows an example of an outbound aggregation. In this example, AS1 and AS2 are coordinating aggregation and announcing only the less specific 128.8.0.0/15 to outside world, but exchanging more specifics between each other. This form of aggregation is useful when some of the components are within AS1 and some are within AS2. When a set of routes are aggregated, the intent is to export only the aggregate route and suppress exporting of the more specifics outside the aggregation boundary. However, to satisfy certain policy and topology constraints (e.g. a multi-homed component), it is often required to export some of the components. The export-comps attributeserves this purpose. Itequals an RPSLexport policy expression as follows (see Section6.2): export-comps: to <peering-1> [action <action-1>] . . . to <peering-N> [action <action-N>] announce <filter> where <filter>filter that matches the more specifics that need to be exportedto the peerings specified. While exporting to <peering-i>, the <action-i> is executed to setoutside thepath attributes.aggregation boundary. If this attribute is missing, more specifics are not exported outside the aggregation boundary. Note that, the<filter>export-comps filter contains an implicit "AND" term with the more specifics of the aggregate.Alaettinoglu et. al. Expires July 15, 1999 [Page 45] Internet Draft RPSL January 15, 1999 route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY export-comps: to as-any announce { 128.8.8.0/24 } Figure 25: Outbound aggregation with export exception.Figure2531 shows an example of an outbound aggregation. In this example, the more specific 128.8.8.0/24 is exported outside AS1 in addition to the aggregate. This is useful, when 128.8.8.0/24 is multi-homed site to AS1 with some other AS. Alaettinoglu et. al. Expires August 10, 1999 [Page 48] Internet Draft RPSL February 10, 1999 route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY export-comps: {128.8.8.0/24} Figure 31: Outbound aggregation with export exception. The inject attribute specifies which routers perform the aggregation and when they perform it. Its syntax is as follow: inject: [at <router-expression>] ... [action <action>] [upon <condition>] where <action> is an action specification (see Section6.1.2),6.1.1), <condition> is a boolean expression described below,and<router-expression> is an expression over router IP addresses and DNS names using operators AND, OR,andNOT. The DNS name can only be used if there<router-expression> isan inet-rtr object for that name that binds the name to IP addresses.as described in Section 5.6. All routers in <router-expression> and in the aggregator AS perform the aggregation. If a <router-expression> is not specified, all routers inside the aggregator AS perform the aggregation. The <action> specification may set path attributes of the aggregate, such as assign a preferences to the aggregate. The upon clause is a boolean condition. The aggregate is generated if and only if this condition is true. <condition> is a boolean expression using the logical operators AND and OR (i.e. operator NOT is not allowed) over: HAVE-COMPONENTS { list of prefixes } EXCLUDE { list of prefixes } STATIC The list of prefixes in HAVE-COMPONENTS can only be more specifics of the aggregate. It evaluates to true when all the prefixes listed are present in the routing table of the aggregating router. The list can also include prefix ranges (i.e. using operators ^-, ^+, ^n, and ^n-m). In this case, atAlaettinoglu et. al. Expires July 15, 1999 [Page 46] Internet Draft RPSL January 15, 1999least one prefix from each prefix range needs to be present in the routing table for the condition to be true. The list of prefixes in EXCLUDE can be arbitrary. It evaluates to true when none of the prefixes listed is present in the routing table. The list can also include prefix ranges, and no prefix in that range should be present in the routing table. The keyword static always evaluates to true. If no upon clause is specified the aggregate is generated if an only if there is a component in the routing Alaettinoglu et. al. Expires August 10, 1999 [Page 49] Internet Draft RPSL February 10, 1999 table (i.e. a more specific that matches the filter in the components attribute). route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY inject: at 1.1.1.1 action dpa = 100; inject: at 1.1.1.2 action dpa = 110; route: 128.8.0.0/15 origin: AS1 components: {128.8.0.0/15^-} aggr-mtd: outbound AS-ANY inject: upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16} holes: 128.8.8.0/24 Figure26:32: Examples of inject. Figure2632 shows two examples. In the first case, the aggregate is injected at two routers each one setting the dpa path attribute differently. In the second case, the aggregate is generated only if both 128.8.0.0/16 and 128.9.0.0/16 are present in the routing table, as opposed to the first case where the presence of just one of them is sufficient for injection. The holes attribute lists the component address prefixes which are not reachable through the aggregate route (perhaps that part of the address space is unallocated). The holes attribute is useful for diagnosis purposes. In Figure26,32, the second example has a hole, namely 128.8.8.0/24. This may be due to a customer changing providers and taking this part of the address space with it. 8.1.1 Interaction with policies in aut-num class An aggregate formed is announced to other ASes only if the export policies of the AS allows exporting the aggregate. When the aggregate is formed, the more specifics are suppressed from being exported except to the ASes in aggr-bndry and except the components in export-comps. For such exceptions to happen, the export policies of the AS should explicitly allow exporting of these exceptions.Alaettinoglu et. al. Expires July 15, 1999 [Page 47] Internet Draft RPSL January 15, 1999If an aggregate is not formed (due to the upon clause), then the more specifics of the aggregate can be exported to other ASes, but only if the export policies of the AS allows it. In other words, before a route (aggregate or more specific) is exported it is filtered twice, once based on the route objects, and once based on the export policies of the AS. Alaettinoglu et. al. Expires August 10, 1999 [Page 50] Internet Draft RPSL February 10, 1999 route: 128.8.0.0/16 origin: AS1 route: 128.9.0.0/16 origin: AS1 route: 128.8.0.0/15 origin: AS1 aggr-bndry: AS1 or AS2 or AS3 aggr-mtd: outbound AS3 or AS4 or AS5 components: {128.8.0.0/16, 128.9.0.0/16} inject: upon HAVE-COMPONENTS {128.9.0.0/16, 128.8.0.0/16} aut-num: AS1 export: to AS2 announce AS1 export: to AS3 announce AS1 and not {128.9.0.0/16} export: to AS4 announce AS1 export: to AS5 announce AS1 export: to AS6 announce AS1 Figure27:33: Interaction with policies in aut-num class. In Figure2733 shows an interaction example. By examining the route objects, the more specifics 128.8.0.0/16 and 128.9.0.0/16 should be exchanged between AS1, AS2 and AS3 (i.e. the aggregation boundary). Outbound aggregation is done to AS4 and AS5 and not to AS3, since AS3 is in the aggregation boundary. The aut-num object allows exporting both components to AS2, but only the component 128.8.0.0/16 to AS3. The aggregate can only be formed if both components are available. In this case, only the aggregate is announced to AS4 and AS5. However, if one of the components is not available the aggregate will not be formed, and any available component or more specific will be exported to AS4 and AS5. Regardless of aggregation is performed or not, only the more specifics will be exported to AS6 (it is not listed in the aggr-mtd attribute). When doing an inbound aggregation, configuration generators may eliminating the aggregation statements on routers where import policy of the AS prohibits importing of any more specifics.Alaettinoglu et. al. Expires July 15, 1999 [Page 48] Internet Draft RPSL January 15, 19998.1.2 Ambiguity resolution with overlapping aggregates When several aggregate routes are specified and they overlap, i.e. one is less specific of the other, they must be evaluated more specific to less specific order. When an outbound aggregation is performed for a peer, the aggregate and the components listed in the export-comps attribute for that peer are available for generating the next less specific aggregate. Alaettinoglu et. al. Expires August 10, 1999 [Page 51] Internet Draft RPSL February 10, 1999 The components that are not specified in the export-comps attribute are not available. A route is exportable to an AS if it is the least specific aggregate exportable to that AS or it is listed in the export-comps attribute of an exportable route. Note that this is a recursive definition. route: 128.8.0.0/15 origin: AS1 aggr-bndry: AS1 or AS2 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.8.0.0/16, 128.9.0.0/16} route: 128.10.0.0/15 origin: AS1 aggr-bndry: AS1 or AS3 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.10.0.0/16, 128.11.0.0/16} export-comps:to as-any announce{128.11.0.0/16} route: 128.8.0.0/14 origin: AS1 aggr-bndry: AS1 or AS2 or AS3 aggr-mtd: outbound inject: upon HAVE-COMPONENTS {128.8.0.0/15, 128.10.0.0/15} export-comps:to as-any announce{128.10.0.0/15} Figure28:34: Overlapping aggregations. In Figure28,34, AS1 together with AS2 aggregates 128.8.0.0/16 and 128.9.0.0/16 into 128.8.0.0/15. Together with AS3, AS1 aggregates 128.10.0.0/16 and 128.11.0.0/16 into 128.10.0.0/15. But altogether they aggregate these four routes into 128.8.0.0/14. Assuming all four components are available, a router in AS1 for an outside AS, say AS4, will first generate 128.8.0.0/15 and 128.10.0.0/15. This will make 128.8.0.0/15, 128.10.0.0/15 and its exception 128.11.0.0/16 available for generating 128.8.0.0/14. The router will then generate 128.8.0.0/14 from these three routes. Hence for AS4, 128.8.0.0/14 and its exception 128.10.0.0/15 and its exception 128.11.0.0/16 will be exportable. For AS2, a router in AS1 will only generate 128.10.0.0/15. Hence, 128.10.0.0/15 and its exception 128.11.0.0/16 will be exportable. Note that 128.8.0.0/16 and 128.9.0.0/16 are also exportable since they did notAlaettinoglu et. al. Expires July 15, 1999 [Page 49] Internet Draft RPSL January 15, 1999participate in an aggregate exportable to AS2. Similarly, for AS3, a router in AS1 will only generate 128.8.0.0/15. In this case 128.8.0.0/15, 128.10.0.0/16, 128.11.0.0/16 are exportable. Alaettinoglu et. al. Expires August 10, 1999 [Page 52] Internet Draft RPSL February 10, 1999 8.2 Specifying Static Routes The inject attribute can be used to specify static routes by using "upon static" as the condition: inject: [at<router>]<router-expression>] ... [action <action>] upon static In this case, the<router>routers in <router-expression> executes the <action> and injects the route to the interAS routing system statically. <action> may set certain route attributes such as a next-hop router or a cost. In the following example, the router 7.7.7.1 injects the route 128.7.0.0/16. The next-hop routers (in this example, there are two next-hop routers) for this route are 7.7.7.2 and 7.7.7.3 and the route has a cost of 10 over 7.7.7.2 and 20 over 7.7.7.3. route: 128.7.0.0/16 origin: AS1 inject: at 7.7.7.1 action next-hop = 7.7.7.2; cost = 10; upon static inject: at 7.7.7.1 action next-hop = 7.7.7.3; cost = 20; upon static 9 inet-rtr Class Routers are specified using the inet-rtr class. The attributes of the inet-rtr class are shown in Figure29.35. The inet-rtr attribute is a valid DNS name of the router described. Each alias attribute, if present, is a canonical DNS name for the router. The local-as attribute specifies the AS number of the AS which owns/operates this router.The value of an ifaddr attribute has the following syntax: <ipv4-address> masklen <integer> [action <action>] The IP address and the mask length are mandatory for each interface. Alaettinoglu et. al. Expires July 15, 1999 [Page 50] Internet Draft RPSL January 15, 1999Attribute Value Type inet-rtr <dns-name> mandatory, single-valued, class key alias <dns-name> optional, multi-valued local-as <as-number> mandatory, single-valued ifaddr see description in text mandatory, multi-valued peer see description in text optional, multi-valued member-of list of <rtr-set-names> optional, multi-valued Figure29:35: inet-rtr Class Attributes The value of an ifaddr attribute has the following syntax: Alaettinoglu et. al. Expires August 10, 1999 [Page 53] Internet Draft RPSL February 10, 1999 <ipv4-address> masklen <integer> [action <action>] The IP address and the mask length are mandatory for each interface. Optionally an action can be specified to set other parameters of this interface. Figure3036 presents an example inet-rtr object. The name of the router is ``amsterdam.ripe.net''. ``amsterdam1.ripe.net'' is a canonical name for the router. The router is connected to 4 networks. Its IP addresses and mask lengths in those networks are specified in the ifaddr attributes. inet-rtr: Amsterdam.ripe.net alias: amsterdam1.ripe.net local-as: AS3333 ifaddr: 192.87.45.190 masklen 24 ifaddr: 192.87.4.28 masklen 24 ifaddr: 193.0.0.222 masklen 27 ifaddr: 193.0.0.158 masklen 27 peer: BGP4 192.87.45.195 asno(AS3334), flap_damp() Figure30:36: inet-rtr Objects Each peer attribute, if present, specifies a protocol peering with another router. The value of a peer attribute has the following syntax: <protocol> <ipv4-address> <options> | <protocol> <inet-rtr-name> <options> | <protocol> <rtr-set-name> <options> | <protocol> <peering-set-name> <options> where <protocol> is a protocol name, <ipv4-address> is the IP address of the peer router, and <options> is a comma separated list of peering options for <protocol>. Instead of the peer's IP address, its inet-rtr-name can be used. Possible protocol names and attributes are defined in the dictionary (please see Section 7). In the above example, the router has a BGP peering with the router 192.87.45.195 in AS3334 and turns the flap damping on when importing routes from this router. Instead of a single peer, a group of peers can be specified by using the <rtr-set-name> and <peering-set-name> forms. If <peering-set-name> form is being used only the peerings in the corresponding peering set that are with this router are included. Figure 37 shows an example inet-rtr object with peering groups. Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page51]54] Internet Draft RPSLJanuary 15,February 10, 1999 rtr-set: rtrs-ibgp-peers members: 1.1.1.1, 2.2.2.2, 3.3.3.3 peering-set: prng-ebgp-peers peering: AS3334 192.87.45.195 peering: AS3335 192.87.45.196 inet-rtr: Amsterdam.ripe.net alias: amsterdam1.ripe.net local-as: AS3333 ifaddr: 192.87.45.190 masklen 24 ifaddr: 192.87.4.28 masklen 24 ifaddr: 193.0.0.222 masklen 27 ifaddr: 193.0.0.158 masklen 27 peer: BGP4 rtrs-ibgp-peers asno(AS3333), flap_damp() peer: BGP4 prng-ebgp-peers asno(PeerAS), flap_damp() Figure 37: inet-rtr Object with peering groups 10 Extending RPSL Our experience with earlier routing policy languages and data formats (PRDB [2], RIPE-81 [8], and RIPE-181 [7]) taught us that RPSL had to be extensible. As a result, extensibility was a primary design goal for RPSL. New routing protocols or new features to existing routing protocols can be easily handled using RPSL's dictionary class. New classes or new attributes to the existing classes can also be added. This section provides guidelines for extending RPSL. These guidelines are designed with an eye toward maintaining backward compatibility with existing tools and databases. We next list the available options for extending RPSL from the most preferred to the least preferred order. 10.1 Extensions by changing the dictionary class The dictionary class is the primary mechanism provided to extend RPSL. Dictionary objects define routing policy attributes, types, and routing protocols. We recommend updating the RPSL dictionary to include appropriate rp- attribute and protocol definitions as new path attributes or router features are introduced. For example, in an earlier version of the RPSL document, it was only possible to specify that a router performs route flap damping on a peer, but it was not possible to specify the parameters of route flap damping. Later the parameters were added by changing the dictionary. Alaettinoglu et. al. Expires August 10, 1999 [Page 55] Internet Draft RPSL February 10, 1999 When changing the dictionary, full compatibility should be maintained. For example, in our flap damping case, we made the parameter specification optional in case this level of detail was not desired by some ISPs. This also achieved compatibility. Any object registered without the parameters will continue to be valid. Any tool based on RPSL is expected to do a default action on routing policy attributes that they do not understand (e.g. issue a warning and otherwise ignore). Hence, old tools upon encountering a flap damping specification with parameters will ignore the parameters. 10.2 Extensions by adding new attributes to existing classes New attributes can be added to any class. To ensure full compatibility, new attributes should not contradict the semantics of the objects they are attached to. Any tool that uses the IRR should be designed so that it ignores attributes that it doesn't understand. Most existing tools adhere to this design principle. We recommend adding new attributes to existing classes when a new aspect ofAlaettinoglu et. al. Expires July 15, 1999 [Page 52] Internet Draft RPSL January 15, 1999a class is discovered. For example, RPSL route class extends its RIPE-181 predecessor by including several new attributes that enable aggregate and static route specification. 10.3 Extensions by adding new classes New classes can be added to RPSL to store new types of policy data. Providing full compatibility is straight forward as long as existing classes are still understood. Since a tool should only query the IRR for the classes that it understand, full compatibility should not be a problem in this case. Before adding a new class, one should question if the information contained in the objects of the new class could have better belonged to some other class. For example, if the geographic location of a router needs to be stored in IRR, it may be tempting to add a new class called, say router-location class. However, the information better belongs to the inet-rtr class, perhaps in a new attribute called location. 10.4 Extensions by changing the syntax of existing RPSL attributes If all of the methods described above fail to provide the desired extension, it may be necessary to change the syntax of RPSL. Any change in RPSL syntax must provide backwards compatibility, and should be considered only as a last resort since full compatibility may not be achievable. However, we Alaettinoglu et. al. Expires August 10, 1999 [Page 56] Internet Draft RPSL February 10, 1999 require that the old syntax to be still valid. 11 Security Consideration This document describes RPSL, a language for expressing routing policies. The language defines a maintainer (mntner class) object which is the entity which controls or "maintains" the objects stored in a database expressed by RPSL. Requests from maintainers can be authenticated with various techniques as defined by the "auth" attribute of the maintainer object. The exact protocols used by IRR's to communicate RPSL objects is beyond the scope of this document, but it is envisioned that several techniques may be used, ranging from interactive query/update protocols to store and forward protocols similar to or based on electronic mail (or even voice telephone calls). Regardless of which protocols are used in a given situation, it is expected that appropriate security techniques such as IPSEC, TLS or PGP/MIME will be utilized.Alaettinoglu et. al. Expires July 15, 1999 [Page 53] Internet Draft RPSL January 15, 199912 Acknowledgements We would like to thank Jessica Yu, Randy Bush, Alan Barrett, Bill Manning, Sue Hares, Ramesh Govindan, Kannan Varadhan, Satish Kumar, Craig Labovitz, Rusty Eddy, David J. LeRoy, David Whipple, Jon Postel, Deborah Estrin, Elliot Schwartz, Joachim Schmitz, Mark Prior, Tony Przygienda, David Woodgate, Rob Coltun, Sanjay Wadhwa, Ardas Cilingiroglu, and the participants of the IETF RPS Working Group for various comments and suggestions. References [1] Internet routing registry. procedures. http://www.ra.net/RADB.tools.docs/, http://www.ripe.net/db/doc.html. [2] Nsfnet policy routing database (prdb). Maintained by MERIT Network Inc., Ann Arbor, Michigan. Contents available from nic.merit.edu.:/nsfnet/announced.networks/nets.tag.now by anonymous ftp. [3] C. Alaettinouglu, T. Bates, E. Gerich, D. Karrenberg, D. Meyer, M. Terpstra, and C. Villamizer. Routing policy specification language (rpsl). Request for Comment RFC-2280, Network Information Center, January 1998. Alaettinoglu et. al. Expires August 10, 1999 [Page 57] Internet Draft RPSL February 10, 1999 [4] C. Alaettinouglu, D. Meyer, and J. Schmitz. Application of routing policy specification language (rpsl) on the internet. Internet Draft draft-ietf-rps-appl-rpsl-01, July 1997. Work in progress. [5] T. Bates. Specifying an `internet router' in the routing registry. Technical Report RIPE-122, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [6] T. Bates, E. Gerich, L. Joncheray, J-M. Jouanigot, D. Karrenberg, M. Terpstra, and J. Yu. Representation of ip routing policies in a routing registry. Technical Report ripe-181, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [7] T. Bates, E. Gerich, L. Joncheray, J-M. Jouanigot, D. Karrenberg, M. Terpstra, and J. Yu. Representation of ip routing policies in a routing registry. Technical Report RFC-1786, Network Information Center, March 1995. [8] T. Bates, J-M. Jouanigot, D. Karrenberg, P. Lothberg, and M. Terpstra. Representation of ip routing policies in the ripe database. Technical Report ripe-81, RIPE, RIPE NCC, Amsterdam, Netherlands, February 1993.Alaettinoglu et. al. Expires July 15, 1999 [Page 54] Internet Draft RPSL January 15, 1999[9] R. Chandra, P. Traina, and T. Li. Bgp communities attribute. Request for Comment RFC-1997, Network Information Center, August 1996. [10] D. Crocker. Standard for the format of arpa internet text messages. Request for Comment RFC-822, Network Information Center, August 1982. [11] V. Fuller, T. Li, J. Yu, and K. Varadhan. Classless Inter-Domain Routing (CIDR): an Address Assignment and Aggregation Strategy, 1993. [12] D. Karrenberg and T. Bates. Description of inter-as networks in the ripe routing registry. Technical Report RIPE-104, RIPE, RIPE NCC, Amsterdam, Netherlands, December 1993. [13] D. Karrenberg and M. Terpstra. Authorisation and notification of changes in the ripe database. Technical Report ripe-120, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [14] B. W. Kernighan and D. M. Ritchie. The C Programming Language. Prentice-Hall, 1978. [15] D. Kessens, W. Woeber, and D. Conrad. Ride referencing. Internet Draft draft-kessens-ride-referencing-00.txt, Network Information Center, August 1997. [16] A. Lord and M. Terpstra. Ripe database template for networks and persons. Technical Report ripe-119, RIPE, RIPE NCC, Amsterdam, Netherlands, October 1994. [17] A. M. R. Magee. Ripe ncc database documentation. Technical Report Alaettinoglu et. al. Expires August 10, 1999 [Page 58] Internet Draft RPSL February 10, 1999 RIPE-157, RIPE, RIPE NCC, Amsterdam, Netherlands, May 1997. [18] P. V. Mockapetris. Domain names - concepts and facilities. Request for Comment RFC-1034, Network Information Center, November 1987. [19] Y. Rekhter. Inter-domain routing protocol (idrp). Journal of Internetworking Research and Experience, 4:61--80, 1993. [20] Y. Rekhter and T. Li. A border gateway protocol 4 (bgp-4). Request for Comment RFC-1771, Network Information Center, March 1995. [21] C. Villamizar, C. Alaettinouglu, D. Meyer, S. Murphy, and C. Orange. Routing policy system security. Internet Draft draft-ietf-rps-auth-01, Network Information Center, May 1998. [22] C. Villamizar, R. Chandra, and R. Govindan. Bgp route flap damping. Internet Draft draft-ietf-idr-route-damp-00, Network Information Center, October 1997. [23] J. Zsako. Pgp authentication for ripe database updates. Internet Draft draft-zsako-ripe-dbsec-pgp-authent-00, Network Information Center, July 1998.Alaettinoglu et. al. Expires July 15, 1999 [Page 55] Internet Draft RPSL January 15, 1999A Routing Registry Sites The set of routing registries as of November 1996 are RIPE, RADB, CANet, MCI and ANS. You may contact one of these registries to find out the current list of registries. B Grammar Rules In this section we provide formal grammar rules for RPSL. Basic data types are defined in Section 2. We do not provide formal grammar rules for attributes whose values are of basic types or list of basic types. //**** Generic Attributes************************************************************************************************* changed_attribute: ATTR_CHANGED TKN_EMAIL TKN_INT //**** aut-num class ****************************************************** ////as_expr //////////////////////////////////////////////////////////// opt_as_expr:as_expression ////////////////////////////////////////////////////// opt_as_expression: |as_expr as_expr: as_expras_expression Alaettinoglu et. al. Expires August 10, 1999 [Page 59] Internet Draft RPSL February 10, 1999 as_expression: as_expression OP_ORas_expr_termas_expression_term |as_expr_term as_expr_term: as_expr_termas_expression_term as_expression_term: as_expression_term OP_ANDas_expr_factoras_expression_factor |as_expr_factor as_expr_factor: OP_NOT as_expr_factoras_expression_term KEYW_EXCEPT as_expression_factor | as_expression_factor as_expression_factor: '('as_expras_expression ')' |as_expr_operand as_expr_operand:as_expression_operand as_expression_operand: TKN_ASNO | TKN_ASNAME ////rtr_expr /////////////////////////////////////////////////////////// opt_rtr_expr:router_expression ////////////////////////////////////////////////// opt_router_expression: |rtr_expr opt_rtr_expr_with_at:router_expression opt_router_expression_with_at: | KEYW_ATrtr_expr rtr_expr: rtr_exprrouter_expression router_expression: router_expression OP_ORrtr_expr_termrouter_expression_term |rtr_expr_term Alaettinoglu et. al. Expires July 15, 1999 [Page 56] Internet Draft RPSL January 15, 1999 rtr_expr_term: rtr_expr_termrouter_expression_term router_expression_term: router_expression_term OP_ANDrtr_expr_factorrouter_expression_factor |rtr_expr_factor rtr_expr_factor: OP_NOT rtr_expr_factorrouter_expression_term KEYW_EXCEPT router_expression_factor | router_expression_factor router_expression_factor: '('rtr_exprrouter_expression ')' |rtr_expr_operand rtr_expr_operand:router_expression_operand router_expression_operand: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME //// peering //////////////////////////////////////////////////////////// peering:as_expr opt_rtr_expr opt_rtr_expr_with_atas_expression opt_router_expression opt_router_expression_with_at | TKN_PRNGNAME //// action ///////////////////////////////////////////////////////////// opt_action: | KEYW_ACTION action action: single_action | action single_action single_action: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')' ';' | TKN_RP_ATTR TKN_OPERATOR list_item ';' Alaettinoglu et. al. Expires August 10, 1999 [Page 60] Internet Draft RPSL February 10, 1999 | TKN_RP_ATTR '(' generic_list ')' ';' | TKN_RP_ATTR '[' generic_list ']' ';' | ';' //// filter ///////////////////////////////////////////////////////////// filter: filter OP_OR filter_term | filter filter_term %prec OP_OR | filter_term filter_term : filter_term OP_AND filter_factor | filter_factor filter_factor : OP_NOT filter_factor | '(' filter ')' | filter_operand filter_operand: KEYW_ANY | '<' filter_aspath '>' | filter_rp_attribute | TKN_FLTRNAME | filter_prefix filter_prefix: filter_prefix_operand OP_MS | filter_prefix_operand filter_prefix_operand: TKN_ASNOAlaettinoglu et. al. Expires July 15, 1999 [Page 57] Internet Draft RPSL January 15, 1999| KEYW_PEERAS | TKN_ASNAME | TKN_RSNAME | '{' opt_filter_prefix_list '}' opt_filter_prefix_list: | filter_prefix_list filter_prefix_list: filter_prefix_list_prefix | filter_prefix_list ',' filter_prefix_list_prefix filter_prefix_list_prefix: TKN_PRFXV4 | TKN_PRFXV4RNG filter_aspath: filter_aspath '|' filter_aspath_term | filter_aspath_term filter_aspath_term: filter_aspath_term filter_aspath_closure | filter_aspath_closure filter_aspath_closure: filter_aspath_closure '*' | filter_aspath_closure '?' | filter_aspath_closure '+' | filter_aspath_factor Alaettinoglu et. al. Expires August 10, 1999 [Page 61] Internet Draft RPSL February 10, 1999 filter_aspath_factor: '^' | '$' | '(' filter_aspath ')' | filter_aspath_no filter_aspath_no: TKN_ASNO | KEYW_PEERAS | TKN_ASNAME | '.' | '[' filter_aspath_range ']' | '[' '^' filter_aspath_range ']' filter_aspath_range: | filter_aspath_range TKN_ASNO | filter_aspath_range KEYW_PEERAS | filter_aspath_range '.' | filter_aspath_range TKN_ASNO '-' TKN_ASNO | filter_aspath_range TKN_ASNAME filter_rp_attribute: TKN_RP_ATTR '.' TKN_WORD '(' generic_list ')' | TKN_RP_ATTR TKN_OPERATOR list_item | TKN_RP_ATTR '(' generic_list ')' | TKN_RP_ATTR '[' generic_list ']' //// peering action pair ////////////////////////////////////////////////Alaettinoglu et. al. Expires July 15, 1999 [Page 58] Internet Draft RPSL January 15, 1999import_peering_action_list: KEYW_FROM peering opt_action | import_peering_action_list KEYW_FROM peering opt_action export_peering_action_list: KEYW_TO peering opt_action | export_peering_action_list KEYW_TO peering opt_action //// import/export factor /////////////////////////////////////////////// import_factor: import_peering_action_list KEYW_ACCEPT filter import_factor_list: import_factor ';' | import_factor_list import_factor ';' export_factor: export_peering_action_list KEYW_ANNOUNCE filter export_factor_list: export_factor ';' | export_factor_list export_factor ';' //// import/export term ///////////////////////////////////////////////// import_term: import_factor ';' | '{' import_factor_list '}' export_term: export_factor ';' Alaettinoglu et. al. Expires August 10, 1999 [Page 62] Internet Draft RPSL February 10, 1999 | '{' export_factor_list '}' //// import/exportexpr ///////////////////////////////////////////////// import_expr:expression /////////////////////////////////////////// import_expression: import_term | import_term KEYW_REFINEimport_exprimport_expression | import_term KEYW_EXCEPTimport_expr export_expr:import_expression export_expression: export_term | export_term KEYW_REFINEexport_exprexport_expression | export_term KEYW_EXCEPTexport_exprexport_expression //// protocol /////////////////////////////////////////////////////////// opt_protocol_from: | KEYW_PROTOCOL tkn_word opt_protocol_into: | KEYW_INTO tkn_word //**** import/export attributes ******************************************* import_attribute: ATTR_IMPORT | ATTR_IMPORT opt_protocol_from opt_protocol_into import_factor export_attribute: ATTR_EXPORT | ATTR_EXPORT opt_protocol_from opt_protocol_into export_factorAlaettinoglu et. al. Expires July 15, 1999 [Page 59] Internet Draft RPSL January 15, 1999opt_default_filter: | KEYW_NETWORKS filter default_attribute: ATTR_DEFAULT KEYW_TO peering filter_attribute: ATTR_FILTER filter peering_attribute: ATTR_PEERING peering //**** inet-rtr class ***************************************************** ifaddr_attribute: ATTR_IFADDR TKN_IPV4 KEYW_MASKLEN TKN_INT opt_action //// peer attribute ///////////////////////////////////////////////////// opt_peer_options: | peer_options peer_options: peer_option | peer_options ',' peer_option peer_option: tkn_word '(' generic_list ')' Alaettinoglu et. al. Expires August 10, 1999 [Page 63] Internet Draft RPSL February 10, 1999 peer_id: TKN_IPV4 | TKN_DNS | TKN_RTRSNAME | TKN_PRNGNAME peer_attribute: ATTR_PEER tkn_wordTKN_IPV4peer_id opt_peer_options //**** route class ******************************************************** aggr_bndry_attribute: ATTR_AGGR_BNDRYas_expras_expression aggr_mtd_attribute: ATTR_AGGR_MTD KEYW_INBOUND | ATTR_AGGR_MTD KEYW_OUTBOUNDopt_as_expr export_comps_attribute: ATTR_EXPORT_COMPS export_factoropt_as_expression //// inject attribute ///////////////////////////////////////////////////opt_inject_expr:opt_inject_expression: | KEYW_UPONinject_expr inject_expr: inject_exprinject_expression inject_expression: inject_expression OP_ORinject_expr_terminject_expression_term |inject_expr_term inject_expr_term: inject_expr_terminject_expression_term inject_expression_term: inject_expression_term OP_ANDinject_expr_factorinject_expression_factor |inject_expr_factor inject_expr_factor:inject_expression_factor inject_expression_factor: '('inject_exprinject_expression ')' |inject_expr_operand inject_expr_operand:inject_expression_operand inject_expression_operand: KEYW_STATIC | KEYW_HAVE_COMPONENTS '{' opt_filter_prefix_list '}' | KEYW_EXCLUDE '{' opt_filter_prefix_list '}' inject_attribute: ATTR_INJECTopt_rtr_expr_with_atopt_router_expression_with_at opt_actionopt_inject_expr Alaettinoglu et. al. Expires July 15, 1999 [Page 60] Internet Draft RPSL January 15, 1999opt_inject_expression //// components attribute /////////////////////////////////////////////// opt_atomic: | KEYW_ATOMIC components_list: | filter | components_list KEYW_PROTOCOL tkn_word filter components_attribute: ATTR_COMPONENTS opt_atomic components_list //**** route-set ********************************************************** opt_rs_members_list: /* empty list */ | rs_members_list Alaettinoglu et. al. Expires August 10, 1999 [Page 64] Internet Draft RPSL February 10, 1999 rs_members_list: rs_member | rs_members_list ',' rs_member rs_member: TKN_ASNO | TKN_ASNO OP_MS | TKN_ASNAME | TKN_ASNAME OP_MS | TKN_RSNAME | TKN_RSNAME OP_MS | TKN_PRFXV4 | TKN_PRFXV4RNG rs_members_attribute: ATTR_RS_MEMBERS opt_rs_members_list //**** dictionary ********************************************************* rpattr_attribute: ATTR_RP_ATTR TKN_WORD methods | ATTR_RP_ATTR TKN_RP_ATTR methods methods: method | methods method method: TKN_WORD '(' ')' | TKN_WORD '(' typedef_type_list ')' | TKN_WORD '(' typedef_type_list ',' TKN_3DOTS ')' | KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ')' | KEYW_OPERATOR TKN_OPERATOR '(' typedef_type_list ',' TKN_3DOTS ')' //// typedef attribute ///////////////////////////////////////////////// typedef_attribute: ATTR_TYPEDEF TKN_WORD typedef_type typedef_type_list: typedef_type | typedef_type_list ',' typedef_typeAlaettinoglu et. al. Expires July 15, 1999 [Page 61] Internet Draft RPSL January 15, 1999typedef_type: KEYW_UNION typedef_type_list | KEYW_RANGE KEYW_OF typedef_type | TKN_WORD | TKN_WORD '[' TKN_INT ',' TKN_INT ']' | TKN_WORD '[' TKN_REAL ',' TKN_REAL ']' | TKN_WORD '[' enum_list ']' | KEYW_LIST '[' TKN_INT ':' TKN_INT ']' KEYW_OF typedef_type | KEYW_LIST KEYW_OF typedef_type enum_list: tkn_word | enum_list ',' tkn_word //// protocol attribute ///////////////////////////////////////////////// protocol_attribute: ATTR_PROTOCOL tkn_word protocol_options Alaettinoglu et. al. Expires August 10, 1999 [Page 65] Internet Draft RPSL February 10, 1999 protocol_options: | protocol_options protocol_option protocol_option: KEYW_MANDATORY method | KEYW_OPTIONAL method //**** Token Definitions ************************************************ //// flex macros used in token definitions ////////////////////////////// INT [[:digit:]]+ SINT [+-]?{INT} REAL [+-]?{INT}?\.{INT}({WS}*E{WS}*[+-]?{INT})? NAME [[:alpha:]]([[:alnum:]_-]*[[:alnum:]])? ASNO AS{INT} ASNAME AS-[[:alnum:]_-]*[[:alnum:]] RSNAME RS-[[:alnum:]_-]*[[:alnum:]] RTRSNAME RTRS-[[:alnum:]_-]*[[:alnum:]] PRNGNAME PRNG-[[:alnum:]_-]*[[:alnum:]] FLTRNAME FLTR-[[:alnum:]_-]*[[:alnum:]] IPV4 [0-9]+(\.[0-9]+){3,3} PRFXV4 {IPV4}\/[0-9]+ PRFXV4RNG {PRFXV4}("^+"|"^-"|"^"{INT}|"^"{INT}-{INT}) ENAMECHAR [^()<>,;:\\\"\.[\] \t\r] ENAME ({ENAMECHAR}+(\.{ENAMECHAR}+)*\.?)|(\"[^\"@\\\r\n]+\") DNAME [[:alnum:]_-]+ //// Token Definitions ////////////////////////////////////////////////// TKN_INT {SINT} TKN_INT {INT}:{INT} if each {INT} is two octets TKN_INT {INT}.{INT}.{INT}.{INT} if each {INT} is one octet TKN_REAL {REAL} TKN_STRING Same as in programming language C TKN_IPV4 {IPV4} TKN_PRFXV4 {PRFXV4} TKN_PRFXV4RNG {PRFXV4RNG} TKN_ASNO {ASNO} TKN_ASNAME (({ASNO}|peeras|{ASNAME}):)*{ASNAME} (:({ASNO}|peeras|{ASNAME}))* TKN_RSNAME (({ASNO}|peeras|{RSNAME}):)*{RSNAME} (:({ASNO}|peeras|{RSNAME}))* TKN_RTRSNAME (({ASNO}|peeras|{RTRSNAME}):)*{RTRSNAME} (:({ASNO}|peeras|{RTRSNAME}))* TKN_PRNGNAME (({ASNO}|peeras|{PRNGNAME}):)*{PRNGNAME} (:({ASNO}|peeras|{PRNGNAME}))* TKN_FLTRNAME (({ASNO}|peeras|{FLTRNAME}):)*{FLTRNAME} (:({ASNO}|peeras|{FLTRNAME}))* TKN_BOOLEAN true|false TKN_RP_ATTR {NAME} if defined in dictionary TKN_WORD {NAME} TKN_DNS {DNAME}("."{DNAME})+ TKN_EMAIL {ENAME}@({DNAME}("."{DNAME})+|{IPV4}) Alaettinoglu et. al. Expires August 10, 1999 [Page 66] Internet Draft RPSL February 10, 1999 C Changes from RFC 2280 RFC 2280 [3] contains an earlier version of RPSL. This section summarizes the changes since then. They are as follows: o It is now possible to write integers as sequence of four 1-octet integers (e.g. 1.1.1.1) or as sequence of two 2-octet integers (e.g. 3561:70). Please see Section 2. o The definition of address prefix range is extended so that an address prefix is also an address prefix range. Please see Section 2. o The semantics for a range operator applied to a set containing address prefix ranges is defined (e.g. {30.0.0.0/8^24-28}^27-30). Please see Section 2. o All dates are now in UTC. Please see Section 2. o Plus ('+') character is added to space and tab characters to split an attribute's value to multiple lines (i.e. by starting the following lines with a space, a tab or a plus ('+') character). Please see Section 2. o The withdrawn attribute of route class is removed from the language.Alaettinoglu et. al. Expires July 15, 1999 [Page 62] Internet Draft RPSL January 15, 1999o filter-set class is introduced. Please see Section 5.4. o rtr-set class is introduced. Please see Section 5.5. o peering-set class is introduced. Please see Section 5.6. o Filters can now refer to filter-set names. Please see Section 5.4. o Peerings can now refer to peering-set, rtr-set names. Both local and peer routers can be specified using router expressions. Please see Section 5.6. o The peer attribute of the inet-rtr class can refer to peering-set, rtr-set names. Please see Section 9. o The syntax and semantics of union, and list types and typedef attribute have changed. Please see Section 7. o In the initial dictionary, the typedef attribute defining the community_elm, rp-attribute defining the community attribute has changed. Please see Section 7. oThe syntax and semantics of export-comps attribute of route class have changed. Please see Section 8. oGuideliness for extending RPSL is added. Please see Section 10. Alaettinoglu et. al. Expires August 10, 1999 [Page 67] Internet Draft RPSL February 10, 1999 o Formal grammar rules are added. Please see Appendix B. D Authors' Addresses Cengiz Alaettinoglu USC Information Sciences Institute4676 Admiralty Way, Suite 1001 Marina del Rey, CA 90292email: cengiz@isi.edu Curtis Villamizar ANS email: curtis@ans.net Elise Gerich At Home Network385 Ravendale Drive Mountain View, CA 94043email: epg@home.net David Kessens Qwest Communications950 Seventeenth Street Suite 1900 Denver, CO 80202email: David.Kessens@qwest.net David Meyer University of OregonEugene, OR 97403email: meyer@antc.uoregon.edu Tony Bates Cisco Systems, Inc.170 West Tasman Drive San Jose, CA 95134email: tbates@cisco.comAlaettinoglu et. al. Expires July 15, 1999 [Page 63] Internet Draft RPSL January 15, 1999Daniel Karrenberg RIPE Network Coordination Centre (NCC)Kruislaan 409 NL-1098 SJ Amsterdam Netherlandsemail: dfk@ripe.net Marten Terpstra c/o Bay Networks, Inc.2 Federal St Billerica MA 01821email: marten@BayNetworks.com Alaettinoglu et. al. ExpiresJuly 15,August 10, 1999 [Page64]68] ----