2.5.3 Inter-Domain Routing (idr)

Last Modified: 2003-06-04

Susan Hares <skh@nexthop.com>
Yakov Rekhter <yakov@juniper.net>
Routing Area Director(s):
Bill Fenner <fenner@research.att.com>
Alex Zinin <zinin@psg.com>
Routing Area Advisor:
Bill Fenner <fenner@research.att.com>
Technical Advisor(s):
Randall Atkinson <rja@extremenetworks.com>
Sharon Chisholm <schishol@nortelnetworks.com>
Mailing Lists:
General Discussion: idr@merit.edu
To Subscribe: idr-request@merit.edu
In Body: subscribe idr-post
Archive: ftp://ftp.merit.edu/mail.archives/idr
Description of Working Group:
The Inter-Domain Routing Working Group is chartered to standardize
and promote the Border Gateway Protocol Version 4 (BGP-4) [RFC
1771] capable of supporting policy based routing for TCP/IP
The objective is to promote the use of BGP-4 to support IP version
4 and IP version 6. The working group will continue to work on
improving the scalability of BGP.

The current tasks of the WG are limited to:

- Revise and clarify the base BGP4 document (RFC 1771). Note that
RFC 1771 no longer documents existing practice and one goal of the
update is document existing practice. Determine whether the document
can be advanced as full Standard or needs to recycle at Proposed
or Draft Standard.

- Submit updated base BGP4 MIB to accompany the revised base BGP4

Once these tasks are finished (means WG consensus, WG Last Call,
AD Review, IETF Last Call, and IESG approval for publication), work
will progress on the following:

- Review and Evaluate Existing RFCs on AS Confederations and Route
Reflection. If changes are needed, create and advance revisions.

- Review and evaluate Multiprotocol BGP (RFC 2858) for advancement
as Draft Standard.

- Progress BGP Extended Communities along standards track.

- Extend BGP to support a 4-byte AS number, develop plan for
transitioning to usage of 4-byte AS numbers. Advance support for a
4-byte AS numbers along standards track.

- Produce BGP MIB v2 that includes support for AS Confederations,
Route Reflection, Communities, Multi-Protocol BGP, BGP Extended
Communities, support for 4-byte AS numbers.

- Progress along the IETF standards track a BGP-based mechanism
that allows a BGP speaker to send to its BGP peer a set of route
filters that the peer would use to constrain/filter its outbound
routing updates to the speaker. Currently defined in

- Progress along standards track an Outbound Router Filter (ORF)
type for BGP, that can be used to perform aspath based route
filtering. The ORF-type will support aspath based route filtering
as well as regular expression based matching for address groups.
Currently defined in draft-ietf-idr-aspath-orf-00.txt.

- Progress a BGP Graceful Restart mechanism along standards track.

- Progress Subcodes for BGP Cease Notification Message along

- Progress AS-wide Unique BGP Identifier for BGP-4 along standards

- Progress Dynamic Capability for BGP-4 along standards track.

Tasks for this working group are limited to those listed above;
new items to be added to the charter must be approved by the IESG.
Goals and Milestones:
Done  Submit to BGP Capability Advertisement to the IESG
Jan 03  Submit BGP4 document to IESG.
Jan 03  Submit updated base BGP4 MIB to IESG.
Jan 03  Submit BGP Security Vulnerabilities Analysis to IESG
Mar 03  Submit BGP Graceful Restart to IESG
Mar 03  Submit revised text on Multi-Protocol BGP (rfc2858bis) to IESG
Mar 03  Submit BGP MIB v2 to IESG
Mar 03  Submit Extended Communities draft to IESG.
May 03  Submit 4-byte AS ID to IESG
May 03  Submit Outbound Route Filter, Prefix and ASpath ORF draft to IESG
May 03  Submit Subcodes for BGP Cease Notification Message to IESG
May 03  Submit AS-wide Unique BGP Identifier for BGP-4 to IESG
May 03  Submit Dynamic Capability for BGP-4 to IESG
  • - draft-ietf-idr-bgp4-20.txt
  • - draft-ietf-idr-bgp4-mib-11.txt
  • - draft-ietf-idr-route-filter-09.txt
  • - draft-ietf-idr-restart-07.txt
  • - draft-ietf-idr-as4bytes-07.txt
  • - draft-ietf-idr-bgp-ext-communities-06.txt
  • - draft-ietf-idr-aspath-orf-05.txt
  • - draft-ietf-idr-bgp4-mibv2-03.txt
  • - draft-ietf-idr-dynamic-cap-04.txt
  • - draft-ietf-idr-cease-subcode-03.txt
  • - draft-ietf-idr-rfc2858bis-03.txt
  • - draft-ietf-idr-bgp-identifier-02.txt
  • - draft-ietf-idr-bgp-gr-survey-00.txt
  • - draft-ietf-idr-bgp-analysis-03.txt
  • - draft-ietf-idr-bgp-issues-01.txt
  • - draft-ietf-idr-bgp-vuln-00.txt
  • - draft-ietf-idr-bgp4-experience-protocol-01.txt
  • - draft-ietf-idr-rfc3065bis-00.txt
  • Request For Comments:
    Border Gateway Protocol BGP (RFC 1105) (36632 bytes) obsoleted by RFC 1163
    Border Gateway Protocol BGP (RFC 1105) (36632 bytes) obsoleted by RFC 1267
    Application of the Border Gateway Protocol in the Internet (RFC 1164) (54988 bytes) obsoleted by RFC 1268
    A Border Gateway Protocol (BGP) (RFC 1163) (67778 bytes) obsoleted by RFC 1267
    A Border Gateway Protocol 3 (BGP-3) (RFC 1267) (80724 bytes)
    Application of the Border Gateway Protocol in the Internet (RFC 1268) (31102 bytes) obsoleted by RFC 1655
    Definitions of Managed Objects for the Border Gateway Protocol (Version 3) (RFC 1269) (25717 bytes)
    Experience with the BGP Protocol (RFC 1266) (21938 bytes)
    BGP Protocol Analysis (RFC 1265) (20728 bytes)
    BGP OSPF Interaction (RFC 1364) (32121 bytes) obsoleted by RFC 1403
    Default Route Advertisement In BGP2 And BGP3 Versions Of The Border Gateway Protocol (RFC 1397) (4124 bytes)
    BGP OSPF Interaction (RFC 1403) (36173 bytes)
    BGP-4 Protocol Document Roadmap and Implementation Experience (RFC 1656) (7705 bytes) obsoleted by RFC 1773
    Definitions of Managed Objects for the Fourth Version of the Border Gateway Protocol (BGP-4) using SMIv2 (RFC 1657) (45504 bytes)
    A Border Gateway Protocol 4 (BGP-4) (RFC 1654) (130118 bytes) obsoleted by RFC 1771
    Application of the Border Gateway Protocol in the Internet (RFC 1655) (43664 bytes) obsoleted by RFC 1772
    BGP4/IDRP for IP---OSPF Interaction (RFC 1745) (43675 bytes)
    A Border Gateway Protocol 4 (BGP-4) (RFC 1771) (131903 bytes)
    Experience with the BGP-4 protocol (RFC 1773) (19936 bytes)
    BGP-4 Protocol Analysis (RFC 1774) (23823 bytes)
    A BGP/IDRP Route Server alternative to a full mesh routing (RFC 1863) (37426 bytes)
    Guidelines for creation, selection, and registration of an Autonomous System (AS) (RFC 1930) (22073 bytes)
    Autonomous System Confederations for BGP (RFC 1965) (13575 bytes) obsoleted by RFC 3065
    BGP Route Reflection An alternative to full mesh IBGP (RFC 1966) (14320 bytes)
    An Application of the BGP Community Attribute in Multi-home Routing (RFC 1998) (16953 bytes)
    BGP Communities Attribute (RFC 1997) (8275 bytes)
    Using a Dedicated AS for Sites Homed to a Single Provider (RFC 2270) (12063 bytes)
    Multiprotocol Extensions for BGP-4 (RFC 2283) (18946 bytes) obsoleted by RFC 2858
    Protection of BGP Sessions via the TCP MD5 Signature Option (RFC 2385) (12315 bytes)
    BGP Route Flap Damping (RFC 2439) (86402 bytes)
    A Framework for Inter-Domain Route Aggregation (RFC 2519) (25394 bytes)
    Use of BGP-4 Multiprotocol Extensions for IPv6 Inter-Domain Routing (RFC 2545) (10209 bytes)
    BGP Route Reflection An alternative to full mesh IBGP (RFC 2796) (20174 bytes)
    Capabilities Advertisement with BGP-4 (RFC 2842) (8366 bytes) obsoleted by RFC 3392
    Multiprotocol Extensions for BGP-4 (RFC 2858) (23305 bytes)
    Route Refresh Capability for BGP-4 (RFC 2918) (7354 bytes)
    Autonomous System Confederations for BGP (RFC 3065) (20529 bytes)
    Border Gateway Protocol (BGP) Persistent Route Oscillation Condition (RFC 3345) (38137 bytes)
    Capabilities Advertisement with BGP-4 (RFC 3392) (9885 bytes)
    Security Requirements for Keys used with the TCP MD5 Signature Option (RFC 3562) (14965 bytes)

    Current Meeting Report

    IETF 57 IDR Minutes
    Chairs: Yakov Rekhter, Sue Hares
    ID Document Status (chairs)
    - Base Spec done! Will post -21 after IETF.
    - See slides
    Avoid BGP Best Path Transition From one External to Another
    -  BGP identifier used in last phases of BGP routes selection
    -  Appear random
    -  Subject to change
    -  Reduces stability
    -  Proposed solution: Don't eliminate either path due to BGP ID during path 
    -      Exception: AS Confederations; parallel sessions
    - Advantages: stability, reduce iBGP oscillation
    - Request to adopt as WG draft, but WG is in closed status until base doc is 
    Advertising Equal Cost Multipath Routes in BGP
    - Route reflector only advertises route that it installs
    - May not be optimal for all RR clients or external peers
    - May lead to route oscillation
    - Advertise two paths to destination
    - Proposal: ECMP-NEXT-HOP attribute
         If specified, second advertisement is not
    CHEN: I don't think that this is adequate to prevent route 
    Bhatia: It will because multiple paths are advertised
    CHEN: How is this different from last presentation
    Bhatia: Don't need to change encoding
    CHEN: Advertising best external route also solves oscillation problem. 
    Without changing spec.
    Marques: Draft should be named "How to advertise multiple paths in BGP". 
    Look at Alvero's draft.
    Yakov: Also look at how MP-BGP addresses this
    BGPv4 SAFI-Specific Attribute
    The Tunnel SAFI
    - Exchange tunnel endpoint information
    - avoid o(n^2) configuration problem
    - Proposal: Use BGP to advertise tunnel endpoints
    -          SAFI specific Attribute carries tunnel attributes
    - SAFI specific attribute value contains TLVs
    - TLV context determined by type field
    - Negotiated capability
    Hares: Whats the cookie for
    kapoor: Its defined in l2tpv3.
    Yakov: Need discussion on mailing list. Unbundle SAFI discussion from 
    discussion of whether we need a new attribute.
    Yakov: How do we control type codes?
    Kapoor: Options - IANA, WG consensus; we can talk about it
    Yakov: Do you have concept of transitive or non-transitive TLV
    Kapoor: Attribute is transitive. All TLV inherit.
    Multiprotocol Next Hop Attribute
    - need to advertise next hop different from AF of NLRI
    - may need to advertise multiple next-hops for a prefix
    - may need to advertise next-hop specific parameters (e.g., label per nh).
    Yakov: Motivations; load balancing, v4 over v6. There are existing apps 
    where encoding of NLRI and Next hop are different.
    Gargi: If we wanted to load balance across two next hops of different 
    type, we could not.
    iBGP Auto Mesh
    - motivation: Autodiscover iBGP peers
    - flood BGP config via IGP
         bgp autodiscover TLV flooded in IGP
    - no change to BGP machinery
    Dave Ward: What happens during graceful restart?
    Robert: We don't reflood if configuration is not changing
    Chen: Does it help much if iBGP congig is not big How will you carry MD5 
    Robert: MD5 keys will be same for all speakers.
    Chen: How does this work for RR clients
    Robert: cluster id on client
    Parantap: We do static config. If you miss one, it really bad. We don't 
    need this. We don't encourage you to touch ISIS.
    Signalling tunneling Encaps
    - Mechanism for signaling PE tunnel encap capabilities.
    - Motivations:
     o Blackhole Avoidance
     o Co-existing MPLS & IP encap
    -BGP Tunnel Capability SAFI
    -LDP Tunnel Encap Capabilities (may not be necessary per BGP)IANA 
    Alex: The BGP specific part needs to belong in IDR
    Dave: You will work together with Gargi
    Rahul: Yes


    BGP-4 MIB Status, IETF 56
    Avoid BGP Best Path Transition from One External to Another
    BGPv4 SAFI-Specific Attribute
    Advertising Equal Cost Multi-Path Routes in BGP
    Multiprotocol Next Hop Attribute (MP_NH)
    IETF 57 IDR Meeting