draft-ietf-idr-bgp-prefix-orf-03.txt   draft-ietf-idr-bgp-prefix-orf-04.txt 
Network Working Group E. Chen Network Working Group E. Chen
Internet Draft S. Sangli Internet Draft S. Sangli
Expiration Date: November 2006 Cisco Systems Expiration Date: January 2007 Cisco Systems
Address Prefix Based Outbound Route Filter for BGP-4 Address Prefix Based Outbound Route Filter for BGP-4
draft-ietf-idr-bgp-prefix-orf-03.txt draft-ietf-idr-bgp-prefix-orf-04.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
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This document defines a new Outbound Router Filter type for BGP, This document defines a new Outbound Router Filter type for BGP,
termed "Address Prefix Outbound Route Filter", that can be used to termed "Address Prefix Outbound Route Filter", that can be used to
perform address prefix based route filtering. This ORF-type supports perform address prefix based route filtering. This ORF-type supports
prefix length or range based matching, wild-card based address prefix prefix length or range based matching, wild-card based address prefix
matching, as well as the exact address prefix matching for address matching, as well as the exact address prefix matching for address
families. families.
1. Introduction 1. Introduction
The Cooperative Outbound Route Filtering Capability defined in [BGP- The Outbound Route Filtering Capability defined in [BGP-ORF] provides
ORF] provides a mechanism for a BGP speaker to send to its BGP peer a a mechanism for a BGP speaker to send to its BGP peer a set of
set of Outbound Route Filters (ORFs) that can be used by its peer to Outbound Route Filters (ORFs) that can be used by its peer to filter
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
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In addition, the "Maxlen" must be no more than the maximum length (in In addition, the "Maxlen" must be no more than the maximum length (in
bits) of a host address for a given address family [BGP-MP]. bits) of a host address for a given address family [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 [BGP- 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 "Type ORF], and the remaining fields of the entry is encoded in the "Type
specific part" as follows. 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
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 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 the to the ORF entry only if the NLRI match condition as listed in Table
following table is satisfied. 1 is satisfied.
ORF Entry NLRI ORF Entry NLRI
Minlen Maxlen Match Condition Minlen Maxlen Match Condition
+------------------------------------------------------+ +------------------------------------------------------+
| un-spec. un-spec. NLRI.legnth == ORF.length | | un-spec. un-spec. NLRI.legnth == ORF.length |
+------------------------------------------------------+ +------------------------------------------------------+
| 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
When more than one Address Prefix ORF entry match the NLRI of the When more than one Address Prefix ORF entry match 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
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This extension to BGP does not change the underlying security issues. This extension to BGP does not change the underlying security issues.
7. Normative References 7. Normative References
[BGP-4] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol [BGP-4] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway Protocol
4 (BGP-4)", RFC 4271, January 2006. 4 (BGP-4)", RFC 4271, January 2006.
[BGP-MP] Bates, T., Rekhter, Y., Chandra, R., and D. Katz, [BGP-MP] Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 2858, June 2000. "Multiprotocol Extensions for BGP-4", RFC 2858, June 2000.
[BGP-ORF] Chen, E., and Rekhter, Y., "Cooperative Route Filtering [BGP-ORF] Chen, E., and Rekhter, Y., "Outbound Route Filtering
Capability for BGP-4", draft-ietf-idr-route-filter-13.txt, March Capability for BGP-4", draft-ietf-idr-route-filter-15.txt, July 2006.
2006.
8. Author Information 8. Author Information
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
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