Address-Prefix-Based Outbound Route Filter for BGP-4
RFC 5292
Document | Type | RFC - Proposed Standard (August 2008; No errata) | |
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Authors | Enke Chen , Srihari Sangli | ||
Last updated | 2015-10-14 | ||
Stream | IETF | ||
Formats | plain text html pdf htmlized bibtex | ||
Stream | WG state | (None) | |
Document shepherd | No shepherd assigned | ||
IESG | IESG state | RFC 5292 (Proposed Standard) | |
Action Holders |
(None)
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Consensus Boilerplate | Unknown | ||
Telechat date | |||
Responsible AD | David Ward | ||
Send notices to | (None) |
Network Working Group E. Chen Request for Comments: 5292 S. Sangli Category: Standards Track Cisco Systems August 2008 Address-Prefix-Based Outbound Route Filter for BGP-4 Status of This Memo This document specifies an Internet standards track protocol for the Internet community, and requests discussion and suggestions for improvements. Please refer to the current edition of the "Internet Official Protocol Standards" (STD 1) for the standardization state and status of this protocol. Distribution of this memo is unlimited. Abstract This document defines a new Outbound Router Filter (ORF) type for BGP, termed "Address Prefix Outbound Route Filter", that can be used to perform address-prefix-based route filtering. This ORF-type supports prefix-length- or range-based matching, wild-card-based address prefix matching, as well as the exact address prefix matching for address families. 1. Introduction The Outbound Route Filtering Capability defined in [BGP-ORF] provides a mechanism for a BGP speaker to send to its BGP peer a set of Outbound Route Filters (ORFs) that can be used by its peer to filter its outbound routing updates to the speaker. This documents defines a new ORF-type for BGP, termed "Address Prefix Outbound Route Filter (Address Prefix ORF)", that can be used to perform address-prefix-based route filtering. The Address Prefix ORF supports prefix-length- or range-based matching, wild-card-based address prefix matching, as well as the exact address prefix matching for address families [BGP-MP]. 2. Address Prefix ORF-Type The Address Prefix ORF-Type allows one to express ORFs in terms of address prefixes. That is, it provides address-prefix-based route filtering, including prefix-length- or range-based matching, as well as wild-card address prefix matching. Conceptually, an Address Prefix ORF entry consists of the fields <Sequence, Match, Length, Prefix, Minlen, Maxlen>. Chen & Sangli Standards Track [Page 1] RFC 5292 Address-Prefix-Based ORF for BGP-4 August 2008 The "Sequence" field specifies the relative ordering of the entry among all the Address Prefix ORF entries. The "Match" field specifies whether this entry is "PERMIT" (value 0) or "DENY" (value 1). The "Length" field indicates the length (in bits) of the address prefix. A length of zero indicates a prefix that matches all (as specified by the address family) addresses (with the prefix itself of zero octets). The "Prefix" field contains an address prefix of an address family. The "Minlen" field indicates the minimum prefix length (in bits) that is required for "matching". The field is considered unspecified with a value of 0. The "Maxlen" field indicates the maximum prefix length (in bits) that is required for "matching". The field is considered unspecified with a value of 0. The fields "Sequence", "Length", "Minlen", and "Maxlen" are all unsigned integers. This document imposes the following requirement on the values of these fields: 0 <= Length < Minlen <= Maxlen However, tests related to the "Minlen" or "Maxlen" value should be omitted when the "Minlen" or "Maxlen" field (respectively) is unspecified. In addition, the "Maxlen" value must be no more than the maximum length (in bits) of a host address for a given address family [BGP-MP]. Chen & Sangli Standards Track [Page 2] RFC 5292 Address-Prefix-Based ORF for BGP-4 August 2008 3. Address Prefix ORF Encoding The value of the ORF-Type for the Address Prefix ORF-Type is 64. An Address Prefix ORF entry is encoded as follows. The "Match" field of the entry is encoded in the "Match" field of the common part [BGP-ORF], and the remaining fields of the entry are encoded in the "Type specific part", as shown in Figure 1. +--------------------------------+ | Sequence (4 octets) | +--------------------------------+ | Minlen (1 octet) | +--------------------------------+ | Maxlen (1 octet) | +--------------------------------+ | Length (1 octet) | +--------------------------------+ | Prefix (variable length) | +--------------------------------+ Figure 1: Address Prefix ORF Encoding Note that the "Prefix" field contains the address prefix followed by enough trailing bits to make the end of the field fall on an octet boundary. The value of the trailing bits is irrelevant. 4. Address Prefix ORF Matching In addition to the general matching rules defined in [BGP-ORF],Show full document text