Network Working Group L. Blunk Internet-Draft Merit Network Expires: November 5, 2003 J. Damas Internet Software Consortium F. Parent Viagenie A. Robachevski RIPE NCC May 7, 2003 RPSLng draft-blunk-rpslng-00.txt Status of this Memo This document is an Internet-Draft and is in full conformance with all provisions of Section 10 of RFC2026. 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 and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." The list of current Internet-Drafts can be accessed at http:// www.ietf.org/ietf/1id-abstracts.txt. The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on November 5, 2003. Copyright Notice Copyright (C) The Internet Society (2003). All Rights Reserved. Abstract This memo presents a new set of simple extensions to the RPSL language enabling the language to document routing policies for the IPv6 and multicast address families currently used in the Internet. Blunk, et al. Expires November 5, 2003 [Page 1] Internet-Draft RPSLng May 2003 1. Introduction RFC 2622 [1] defines the RPSL language for the IPv4 unicast routing protocols and a series of guidelines for extending the RPSL language itself. Additionally, security extensions to the RPSL language are specificed in RFC 2725 [2]. This document proposes to extend RPSL according to the following goals and requirements: provide RPSL extensibility in the dimension of address families. Specifically, to allow users to document routing policy for ipv6 and multicast. the extensions must be backwards compatible and minimise the risk of breaking existing tools. For instance, introducing a new class or attribute would less likely impact a tool or script than changing the syntax of an existing attribute. Section 10 of RFC 2622 [1] provides guidelines for extending RPSL. clarity and non-ambiguity: RPSL information is used by software tools and by humans. minimise duplication of information, particularly when routing policies for different address families are the same. Internet Routing Registry (IRR) system requirements -- It is important to consider the ramifications of RPSL extensions on IRR systems. The capabilities of IRR servers, as well as the established operational practices of users who interact with these servers, must be considered. An important point to note is the fact that there are two address families, corresponding to the two versions of the IP protocol currently in use in the Internet, but there are at least four distinct routing policies that need to be described (IPv4 {unicast|multicast}, IPv6 {unicast|multicast}). Blunk, et al. Expires November 5, 2003 [Page 2] Internet-Draft RPSLng May 2003 2. Specifying routing policy for different address families Routing policy is currently specified in the aut-num class using "import:", "export:", and "default:" attributes. Sometimes it is important to distinguish policy for different address families, as well as a unicast routing policy from a multicast one. Use of existing import, export, and default attributes is not a good option since it breaks backward compatibility and could undermine clarity in the expressions. Keeping this in mind, the "import:", "export:", and "default:" attributes implicitly specify ipv4 unicast policy and remain as defined previously in RPSL, and new multi-protocol (prefixed with the string "mp-") attributes are introduced. These will be described below. 2.1 The afi dictionary attribute In this section we introduce a new dictionary attribute: Address family, , is an RPSL list of address families for which the policy expression should be evaluated. is mandatory within the new multi-protocol attributes introduced in this document. The possible values for are: ipv4 ipv4.unicast (equivalent to ipv4) ipv4.multicast ipv6 ipv6.unicast (equivalent to ipv6) ipv6.multicast Appearance of these values in an attribute's value must be preceded by the keyword afi. An is defined as a comma separated list of one or more afi values. 2.2 ipv6_address predefined type and next-hop dictionary extension In order to support IPv6 addresses specificied with the next-hop rp-attribute, a new predefined dictionary type entitled ipv6_address is added to the RPSL dictionary. In addition, the next-hop rp-attribute is re-defined in the dictionary as follows: Blunk, et al. Expires November 5, 2003 [Page 3] Internet-Draft RPSLng May 2003 rp-attribute: # next hop router in a static route next-hop operator=(union ipv4_address, ipv6_address, enum[self]) 2.3 mp-import, mp-export, and mp-default Three new policy attributes are introduced: mp-import: mp-export: mp-default: These attributes incorporate the afi (address-family) specification. The mp-import and mp-export attributes have both a basic policy specification and a more powerful structured policy specification. The syntax for the basic policy specification of the mp-import and mp-export attributes is as follows: mp-import: [protocol ] [into ] afi from [action ] . . . from [action ] accept mp-export: [protocol ] [into ] afi to [action ] . . . to [action ] announce The mp-import and mp-export policies can be structured. As with RFC 2622 [1], structured policies are recommended only to advanced RPSL users. For the sake of brevity, only the mp-import structured policy syntax is defined below. The mp-export structured policy syntax is expressed in a symmetric way to the mp-import attribute. Blunk, et al. Expires November 5, 2003 [Page 4] Internet-Draft RPSLng May 2003 mp-import ::= [protocol ] [into ] ::= afi accept | afi accept except | afi accept refine ::= | { ... } ::= from [action ]; The specification indicates the AS (and the router if present) ::= [] [at ] | with and being expressions over router IPv4 or IPv6 addresses (specifying their address family with the use of the appropriate "afi " term), inet-rtr names, and rtr-set names using operators AND, OR, and EXCEPT. In the same manner, the expression is the extension of the RPSL expression [section 5.4 of RFC 2622 [1]], requiring the presence of an "afi " term before each address or address-prefix set. The address family may be specified at any level of nesting of , and is valid only within the that contains it. Therefore in the example Blunk, et al. Expires November 5, 2003 [Page 5] Internet-Draft RPSLng May 2003 aut-num: AS65534 mp-import: afi ipv6.unicast,ipv4 from AS1 action pref = 1; accept as-foo except { afi ipv6.unicast,ipv4 from AS2 action pref = 2; accept AS226 except { afi ipv6.unicast from AS3 action pref = 3; accept {3FFE:FFFF::/35} } } the last (rightmost) "except" is evaluated only for the ipv6 unicast address family, while other import-expressions are evaluated for both the ipv6 and ipv4 unicast address families. The evaluation of an is done by evaluating all of its components. Evaluation of peering-sets and filter-sets is constrained by the address family. Such constraints may result in a {NOT ANY} or invalid depending on implicit or explicit definitions of the address family in the set. In the latter case an error is returned. {NOT ANY} filter may issue a warning. Conflicts with explicit or implicit declarations are resolved at runtime, that is during evaluation of a policy expression. For example, when evaluating the following import policy: aut-num: AS2 mp-import: afi ipv6 from AS1 accept {193.0.0.0/22} the filter should be evaluated as {NOT ANY}. aut-num: AS2 mp-import: afi ipv6.unicast { from AS-ANY action med = 0; accept {3FFE:FFFF::/35}; } refine { afi ipv6.unicast from AS1 at 3FFE:FFFF::1 action pref = 1; accept AS-UPSTREAM; from prng6-ebgp-peers action pref = 2; accept AS1; } In this example only ipv6 prefixes originated by AS1 will be collected, and while evaluating AS-UPSTREAM, an as-set, only ipv6 prefixes of the member ASes will be considered. The "mp-default:" attribute is defined as mp-default: afi to [action ] [networks ] Blunk, et al. Expires November 5, 2003 [Page 6] Internet-Draft RPSLng May 2003 using the definitions above for and 2.4 Additional value for A new value has been added for the specification: MPBGP MPBGP is understood to be BGP4 with multi-protocol extensions (often referred to as BGP4+). BGP4+ could not be used as the '+' character is not allowed by the RPSL specification in protocol names. Blunk, et al. Expires November 5, 2003 [Page 7] Internet-Draft RPSLng May 2003 3. New classes and attributes to support the extensions 3.1 as-set Class The as-set class defines a set of Autonomous Systems (AS), specified either directly by listing them in the members attribute, or indirectly by referring to another as-sets or using the mbrs-by-ref facility. More importantly, "In a context that expects a route set (e.g. members attribute of the route-set class), [...] an as-set AS-X defines the set of routes that are originated by the ASes in AS-X.", [section 5.3 of RFC2622]. The as-set class is therefore used to collect a set of route prefixes, which may be restricted to a specific address family. The existing as-set class does not need any modifications. The evaluation of the class must be filtered to obtain prefixes belonging to a particular address family using the traditional filtering mechanism in use in IRR systems today. 3.2 route6 Class The route6 class is the ipv6 equivalent of the route class. As with the route class, the class key for the route6 class is specified by the route6 and origin attribute pair. Other than the route6 attribute, the route6 class shares the same attributes and meanings with the route class. The exception being the inject, holes, components, and exports-comps attributes must specify ipv6 prefixes and addresses rather than ipv4 prefixes and addresses. Attribute Value Type route6 mandatory, single-valued, class key ... (rest an in the route class, with exception listed above) Example: route6: 2001:610:240::/48 origin: AS3333 3.3 route-set Class This class is used in expressions to specify a set of route prefixes. Blunk, et al. Expires November 5, 2003 [Page 8] Internet-Draft RPSLng May 2003 A new attribute "mp-members:" is defined for this class with the following syntax: Attribute Value Type mp-members afi list of or optional, or multi-valued Example: route-set: rs-foo mp-members: afi ipv6 rs-bar # common members with afi constraint mp-members: afi ipv6 rs-foo2, 3FFE:FFFF::/35 # v6 only members... mp-members: afi ipv4 rs-foo3, 128.9.0.0/16 3.4 filter-set Class The new "mp-filter:" attribute defines the set's policy filter. A policy filter is a logical expression which when applied to a set of routes returns a subset of these routes. is defined in section Section 2.3. The relevant parts of the updated filter-set class are shown below: Attribute Value Type filter-set mandatory, single-valued, class key filter optional, single-valued mp-filter afi optional, single-valued ... While the filter and mp-filter attributes are of type "optional", a filter-set must contain one of these two attributes. Implementations should reject instances where both attributes are defined in an object as the interpretation of such a filter-set is undefined. 3.5 peering-set Class The peering set class is updated with a "mp-peering:" attribute, with defined as in section Section 2.3 Blunk, et al. Expires November 5, 2003 [Page 9] Internet-Draft RPSLng May 2003 Attribute Value Type peering-set mandatory, single-valued, class key peering optional, multi-valued mp-peering afi optional, multi-valued ... Example: peering-set: prng-ebgp-peers mp-peering: afi ipv6 AS2 3FFE:FFFF::1 at 3FFE:FFFF::2 3.6 inet-rtr Class This class gets two new attributes: "interface:" which allows the definition of generic interfaces, including the information previously contained in the "ifaddr:" attribute ,as well as support for tunnel definitions. And, "mp-peer:", which includes and extends the functionality of the exisiting "peer:" attribute. Below is the syntax definition for the new "interface:" attribure. Attribute Value Type interface afi
masklen optional, [action ] multi-valued [tunnel ,] The new syntax allows native IPv4 and IPv6 interface definitions as well as the definition of tunnels as virtual interfaces. Without the optional part, this attribute allows the same functionality as the "ifaddr:" attribute but extends it to allow IPv6 addresses. In the case of the interface being a tunnel, the optional part describes the tunnel configuration as follows: indicates the IP address of the remote endpoint of the tunnel. The address family must match that of the local endpoint. denotes the encapsulation used in the tunnel and is one of {GRE,IPv6inIPv4,IPinIP,DVMRP}. Routing policies for these routers should be described in the appropriate classes (eg. peering and autnum). The new "mp-peer:" attribute is defined below. The sole difference between this attribute and the "peer:" attribute is the addition of an specification to allow the use of IPv6 addresses. Blunk, et al. Expires November 5, 2003 [Page 10] Internet-Draft RPSLng May 2003 Attribute Value Type mp-peer afi
or optional, or multi-valued or 3.7 rtr-set Class The rtr-set class is extended with a new attribute, "mp-members:", defined as Attribute Value Type mp-members list of or optional, multi-valued or afi list of This allows specification of ipv4 or ipv6 as values for afi when listing the routers that are members of the set name, or by specifying their IPv4 of IPv6 addresses directly. Blunk, et al. Expires November 5, 2003 [Page 11] Internet-Draft RPSLng May 2003 4. RFC 2725 extensions RFC 2725 [2] introduces an authorization model to address the integrity of policy expressed in routing registries. In particular, two new attributes were defined to support this authorization model, namely, the "mnt-routes" and "mnt-lower" attributes. In RPSLng, these attributes are extended to the route6 and inet6num (described below) classes. Further, the syntax of the existing mnt-routes attribute is modified to allow the optional specification of IPv6 prefix lists when present in inet6num, route6, and aut-num class objects. This optional list of prefixes is a comma-separated list enclosed in curly braces. In the aut-num class, the IPv6 prefixes may be mixed with IPv4 prefixes. Note the inclusion of IPv6 prefixes within a mnt-routes attribute in an aut-num object may conflict with existing implementations of RPSL which support only IPv4 prefixes. However, given the perceived lack of implementation of this optional prefix list, it was considered acceptable to extend the existing definition of the mnt-routes attribute in the aut-num class rather than creating a new attribute type. Attribute Value Type inet6num mandatory, single-valued, class key netname mandatory, single-valued descr mandatory, multi-valued country mandatory, multi-valued admin-c mandatory, multi-valued tech-c mandatory, multi-valued remarks optional, multi-valued notify optional, multi-valued mnt-lower list of optional, multi-valued mnt-routes list of optional, multi-valued mnt-by list of mandatory, multi-valued changed mandatory, multi-valued source mandatory, single-valued The must be a valid two-letter ISO 3166 country code identifier. is a symbolic name for the specified IPv6 address space. It does not have a restriction on RPSL reserved prefixes. These definitions are taken from the RIPE Database Reference Manual [3]. Blunk, et al. Expires November 5, 2003 [Page 12] Internet-Draft RPSLng May 2003 5. Security Considerations This document describes extensions to RPSL, a language for expressing routing policies. The extensions introduce ways of making the configurations currently available for describing IPv4 routing policies to IPv6. They introduce no additional security mechanisms or threats. Blunk, et al. Expires November 5, 2003 [Page 13] Internet-Draft RPSLng May 2003 6. Acknowledgments The authors wish to thank all the people who have contributed to this document through numerous discussions. Particularly Ekaterina Petrusha for highly valuable discussions and suggestions. Shane Kerr, Engin Gunduz, Mark Blanchet and David Kessens participated constructively in many discussions. Finally, Cengiz Alaettinoglu who is still the reference in all things RPSL. Blunk, et al. Expires November 5, 2003 [Page 14] Internet-Draft RPSLng May 2003 References [1] Alaettinoglu, C., Villamizar, C., Gerich, E., Kessens, D., Meyer, D., Bates, T., Karrenberg, D. and M. Terpstra, "Routing Policy Specification Language (RPSL)", RFC 2622, June 1999. [2] Villamizar, C., Alaettinoglu, C., Meyer, D. and S. Murphy, "Routing Policy System Security", RFC 2725, December 1999. [3] Damas, J. and A. Robachevski, "RIPE Database Reference Manual", August 2002. Authors' Addresses Larry Blunk Merit Network EMail: ljb@merit.edu Joao Damas Internet Software Consortium EMail: joao@psg.com Florent Parent Viagenie EMail: Florent.Parent@viagenie.qc.ca Andrei Robachevski RIPE NCC EMail: andrei@ripe.net Blunk, et al. Expires November 5, 2003 [Page 15] Internet-Draft RPSLng May 2003 Intellectual Property Statement The IETF takes no position regarding the validity or scope of any intellectual property or other rights that might be claimed to pertain to the implementation or use of the technology described in this document or the extent to which any license under such rights might or might not be available; neither does it represent that it has made any effort to identify any such rights. 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