draft-ietf-idr-bgp-prefix-orf-05.txt   rfc5292.txt 
Network Working Group E. Chen Network Working Group E. Chen
Internet Draft S. Sangli Request for Comments: 5292 S. Sangli
Expiration Date: January 2009 Cisco Systems Category: Standards Track Cisco Systems
August 2008
Address Prefix Based Outbound Route Filter for BGP-4
draft-ietf-idr-bgp-prefix-orf-05.txt
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Abstract Abstract
This document defines a new Outbound Router Filter (ORF) type for This document defines a new Outbound Router Filter (ORF) type for
BGP, termed "Address Prefix Outbound Route Filter", that can be used BGP, termed "Address Prefix Outbound Route Filter", that can be used
to perform address prefix based route filtering. This ORF-type to perform address-prefix-based route filtering. This ORF-type
supports prefix length or range based matching, wild-card based supports prefix-length- or range-based matching, wild-card-based
address prefix matching, as well as the exact address prefix matching address prefix matching, as well as the exact address prefix matching
for address families. for address families.
1. Introduction 1. Introduction
The Outbound Route Filtering Capability defined in [BGP-ORF] provides 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 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 Outbound Route Filters (ORFs) that can be used by its peer to filter
its outbound routing updates to the speaker. its outbound routing updates to the speaker.
This documents defines a new ORF-type for BGP, termed "Address Prefix This documents defines a new ORF-type for BGP, termed "Address Prefix
Outbound Route Filter (Address Prefix ORF)", that can be used to Outbound Route Filter (Address Prefix ORF)", that can be used to
perform address prefix based route filtering. The Address Prefix ORF perform address-prefix-based route filtering. The Address Prefix ORF
supports prefix length or range based matching, wild-card based supports prefix-length- or range-based matching, wild-card-based
address prefix matching, as well as the exact address prefix matching address prefix matching, as well as the exact address prefix matching
for address families [BGP-MP]. for address families [BGP-MP].
2. Address Prefix ORF-Type 2. Address Prefix ORF-Type
The Address Prefix ORF-Type allows one to express ORFs in terms of The Address Prefix ORF-Type allows one to express ORFs in terms of
address prefixes. That is, it provides address prefix based route address prefixes. That is, it provides address-prefix-based route
filtering, including prefix length or range based matching, as well filtering, including prefix-length- or range-based matching, as well
as wild-card address prefix matching. as wild-card address prefix matching.
Conceptually an Address Prefix ORF entry consists of the fields Conceptually, an Address Prefix ORF entry consists of the fields
<Sequence, Match, Length, Prefix, Minlen, Maxlen>. <Sequence, Match, Length, Prefix, Minlen, Maxlen>.
The "Sequence" field specifies the relative ordering of the entry The "Sequence" field specifies the relative ordering of the entry
among all the Address Prefix ORF entries. among all the Address Prefix ORF entries.
The "Match" field specifies whether this entry is "PERMIT" (value 0), The "Match" field specifies whether this entry is "PERMIT" (value 0)
or "DENY" (value 1). or "DENY" (value 1).
The "Length" field indicates the length in bits of the address The "Length" field indicates the length (in bits) of the address
prefix. A length of zero indicates a prefix that matches all (as prefix. A length of zero indicates a prefix that matches all (as
specified by the address family) addresses (with prefix itself of specified by the address family) addresses (with the prefix itself of
zero octets). zero octets).
The "Prefix" field contains an address prefix of an address family. The "Prefix" field contains an address prefix of an address family.
The "Minlen" field indicates the minimum prefix length in bits that The "Minlen" field indicates the minimum prefix length (in bits) that
is required for "matching". The field is considered as un-specified is required for "matching". The field is considered unspecified with
with value 0. a value of 0.
The "Maxlen" field indicates the maximum prefix length in bits that The "Maxlen" field indicates the maximum prefix length (in bits) that
is required for "matching". The field is considered as un-specified is required for "matching". The field is considered unspecified with
with value 0. a value of 0.
The fields "Sequence", "Length", "Minlen", and "Maxlen" are all The fields "Sequence", "Length", "Minlen", and "Maxlen" are all
unsigned integers. unsigned integers.
This document imposes the following requirement on the values of This document imposes the following requirement on the values of
these fields: these fields:
0 <= Length < Minlen <= Maxlen 0 <= Length < Minlen <= Maxlen
However, tests related to the "Minlen" or "Maxlen" value should be However, tests related to the "Minlen" or "Maxlen" value should be
omitted when the "Minlen" or "Maxlen" field (respectively) is omitted when the "Minlen" or "Maxlen" field (respectively) is
unspecified. unspecified.
In addition, the "Maxlen" value must be no more than the maximum 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- length (in bits) of a host address for a given address family
MP]. [BGP-MP].
3. Address Prefix ORF Encoding 3. Address Prefix ORF Encoding
The value of the ORF-Type for the Address Prefix ORF-Type is 64. 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 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 of the entry is encoded in the "Match" field of the common part
[BGP-ORF], and the remaining fields of the entry is encoded in the [BGP-ORF], and the remaining fields of the entry are encoded in the
"Type specific part" as shown in Figure 1. "Type specific part", as shown in Figure 1.
+--------------------------------+ +--------------------------------+
| Sequence (4 octets) | | Sequence (4 octets) |
+--------------------------------+ +--------------------------------+
| Minlen (1 octet) | | Minlen (1 octet) |
+--------------------------------+ +--------------------------------+
| Maxlen (1 octet) | | Maxlen (1 octet) |
+--------------------------------+ +--------------------------------+
| Length (1 octet) | | Length (1 octet) |
+--------------------------------+ +--------------------------------+
| Prefix (variable length) | | Prefix (variable length) |
+--------------------------------+ +--------------------------------+
Figure 1: Address Prefix ORF Encoding Figure 1: Address Prefix ORF Encoding
Note that the Prefix field contains the address prefix followed by 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 enough trailing bits to make the end of the field fall on an octet
boundary. The value of the trailing bits is irrelevant. boundary. The value of the trailing bits is irrelevant.
4. Address Prefix ORF Matching 4. Address Prefix ORF Matching
In addition to the general matching rules defined in [BGP-ORF], In addition to the general matching rules defined in [BGP-ORF],
several Address Prefix ORF specific matching rules are defined as several Address-Prefix-ORF-specific matching rules are defined as
follows. follows.
Consider an Address Prefix ORF entry, and a route maintained by a BGP Consider an Address Prefix ORF entry, and a route maintained by a BGP
speaker with NLRI in the form of <Prefix, Length>. speaker with Network Layer Reachability Information (NLRI) in the
form of <Prefix, Length>.
The route is considered as "no match" to the ORF entry if the NLRI is The route is considered as "no match" to the ORF entry if the NLRI is
neither more specific than, nor equal to, the <Prefix, Length> fields neither more specific than, nor equal to, the <Prefix, Length> fields
of the ORF entry. of the ORF entry.
When the NLRI is either more specific than, or equal to, the <Prefix, When the NLRI is either more specific than, or equal to, the <Prefix,
Length> fields of the ORF entry, the route is considered as a match Length> fields of the ORF entry, the route is considered as a match
to the ORF entry only if the NLRI match condition as listed in Table to the ORF entry only if the NLRI match condition as listed in Table
1 is satisfied. 1 is satisfied.
skipping to change at page 4, line 38 skipping to change at page 4, line 20
| specified un-spec. NLRI.length >= ORF.Minlen | | specified un-spec. NLRI.length >= ORF.Minlen |
+------------------------------------------------------+ +------------------------------------------------------+
| un-spec. specified NLRI.length <= ORF.Maxlen | | un-spec. specified NLRI.length <= ORF.Maxlen |
+------------------------------------------------------+ +------------------------------------------------------+
| specified specified NLRI.length >= ORF.Minlen | | specified specified NLRI.length >= ORF.Minlen |
| AND NLRI.length <= ORF.Maxlen | | AND NLRI.length <= ORF.Maxlen |
+------------------------------------------------------+ +------------------------------------------------------+
Table 1: Address Prefix ORF Matching Table 1: Address Prefix ORF Matching
When more than one Address Prefix ORF entry match the NLRI of the When more than one Address Prefix ORF entry matches the NLRI of the
route, the "first-match" rule applies. That is, the ORF entry with route, the "first-match" rule applies. That is, the ORF entry with
the smallest sequence number (among all the matching ORF entries) is the smallest sequence number (among all the matching ORF entries) is
considered as the sole match, and it would determine whether the considered as the sole match, and it would determine whether the
route should be advertised. route should be advertised.
The assignment of the sequence numbers is a local matter for the BGP The assignment of the sequence numbers is a local matter for the BGP
speaker that sends the Address Prefix ORF entries. speaker that sends the Address Prefix ORF entries.
5. IANA Considerations 5. IANA Considerations
This document specifies a new Outbound Route Filtering (ORF) type, This document specifies a new Outbound Route Filtering (ORF) type,
Address Prefix ORF. The value of the ORF-type is 64. Address Prefix ORF. The value of the ORF-type is 64.
6. Security Considerations 6. Security Considerations
This extension to BGP does not change the underlying security issues This extension to BGP does not change the underlying security issues
[BGP-4]. in [BGP-4].
7. Normative References 7. Normative References
[BGP-4] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol [BGP-4] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A Border
4 (BGP-4)", RFC 4271, January 2006. Gateway Protocol 4 (BGP-4)", RFC 4271, January 2006.
[BGP-MP] Bates, T., Chandra, R., Rekhter, Y., and D. Katz, [BGP-MP] Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
"Multiprotocol Extensions for BGP-4", RFC 4760, January 2007. "Multiprotocol Extensions for BGP-4", RFC 4760, January
2007.
[BGP-ORF] Chen, E., and Rekhter, Y., "Outbound Route Filtering [BGP-ORF] Chen, E., and Y. Rekhter, "Outbound Route Filtering
Capability for BGP-4", draft-ietf-idr-route-filter-17.txt, June 2008. Capability for BGP-4", RFC 5291, August 2008.
8. Author Information Authors' Addresses
Enke Chen Enke Chen
Cisco Systems, Inc. Cisco Systems, Inc.
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
EMail: enkechen@cisco.com EMail: enkechen@cisco.com
Srihari R. Sangli Srihari R. Sangli
Cisco Systems, Inc. Cisco Systems, Inc.
170 W. Tasman Dr. 170 W. Tasman Dr.
San Jose, CA 95134 San Jose, CA 95134
EMail: rsrihari@cisco.com EMail: rsrihari@cisco.com
9. Intellectual Property Considerations Full Copyright Statement
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Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
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