rfc1266.txt

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Network Working Group                                 Y. Rekhter, Editor
Request for Comments: 1266        T.J. Watson Research Center, IBM Corp.
                                                            October 1991


                    Experience with the BGP Protocol

1. Status of this Memo.

   This memo provides information for the Internet community.  It does
   not specify an Internet standard. Distribution of this memo is
   unlimited.

2. Introduction.

   The purpose of this memo is to document how the requirements for
   advancing a routing protocol to Draft Standard have been satisfied by
   Border Gateway Protocol (BGP). This report documents experience with
   BGP.  This is the second of two reports on the BGP protocol.  As
   required by the Internet Activities Board (IAB) and the Internet
   Engineering Steering Group (IESG), the first report will present a
   performance analysis of the BGP protocol.

   The remaining sections of this memo document how BGP satisfies
   General Requirements specified in Section 3.0, as well as
   Requirements for Draft Standard specified in Section 5.0 of the
   "Internet Routing Protocol Standardization Criteria" document [1].

   This report is based on the work of Dennis Ferguson (University of
   Toronto), Susan Hares (MERIT/NSFNET), and Jessica Yu (MERIT/NSFNET).
   Details of their work were presented at the Twentieth IETF meeting
   (March 11-15, 1991, St. Louis) and are available from the IETF
   Proceedings.

   Please send comments to [e-mail].

3. Acknowledgements.

   The BGP protocol has been developed by the IWG/BGP Working Group of
   the Internet Engineering Task Force. We would like to express our
   deepest thanks to Guy Almes (Rice University) who was the previous
   chairman of the IWG Working Group.  We also like to explicitly thank
   Bob Hinden (BBN) for the review of this document as well as his
   constructive and valuable comments.







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RFC 1266            Experience with the BGP Protocol        October 1991


4. Documentation.

   BGP is an inter-autonomous system routing protocol designed for the
   TCP/IP internets.  Version 1 of the BGP protocol was published in RFC
   1105. Since then BGP Versions 2 and 3 have been developed. Version 2
   was documented in RFC 1163. Version 3 is documented in [3]. The
   changes between versions 1, 2 and 3 are explained in Appendix 3 of
   [3].  Most of the functionality that was present in the Version 1 is
   present in the Version 2 and 3.  Changes between Version 1 and
   Version 2 affect mostly the format of the BGP messages.  Changes
   between Version 2 and Version 3 are quite minor.

   BGP Version 2 removed from the protocol the concept of "up", "down",
   and "horizontal" relations between autonomous systems that were
   present in the Version 1.  BGP Version 2 introduced the concept of
   path attributes.  In addition, BGP Version 2 clarified parts of the
   protocol that were "underspecified".  BGP Version 3 lifted some of
   the restrictions on the use of the NEXT_HOP path attribute, and added
   the BGP Identifier field to the BGP OPEN message. It also clarifies
   the procedure for distributing BGP routes between the BGP speakers
   within an autonomous system.  Possible applications of BGP in the
   Internet are documented in [2].

   The BGP protocol was developed by the IWG/BGP Working Group of the
   Internet Engineering Task Force. This Working Group has a mailing
   list, [e-mail], where discussions of protocol features and
   operation are held. The IWG/BGP Working Group meets regularly during
   the quarterly Internet Engineering Task Force conferences. Reports of
   these meetings are published in the IETF's Proceedings.

5. MIB

   A BGP Management Information Base has been published [4].  The MIB
   was written by Steve Willis ([e-mail]) and John Burruss
   ([e-mail]).

   Apart from a few system variables, the BGP MIB is broken into two
   tables: the BGP Peer Table and the BGP Received Path Attribute Table.
   The Peer Table reflects information about BGP peer connections, such
   as their state and current activity. The Received Path Attribute
   Table contains all attributes received from all peers before local
   routing policy has been applied. The actual attributes used in
   determining a route are a subset of the received attribute table.

   The BGP MIB is quite small. It contains total of 27 objects.






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RFC 1266            Experience with the BGP Protocol        October 1991


6. Security architecture.

   BGP provides flexible and extendible mechanism for authentication and
   security. The mechanism allows to support schemes with various degree
   of complexity. All BGP sessions are authenticated based on the BGP
   Identifier of a peer. In addition, all BGP sessions are authenticated
   based on the autonomous system number advertised by a peer. As part
   of the BGP authentication mechanism, the protocol allows to carry
   encrypted digital signature in every BGP message. All authentication
   failures result in sending the NOTIFICATION messages and immediate
   termination of the BGP connection.

   Since BGP runs over TCP and IP, BGP's authentication scheme may be
   augmented by any authentication or security mechanism provided by
   either TCP or IP.

7. Implementations.

   There are multiple interoperable implementations of BGP currently
   available. This section gives a brief overview of the three
   completely independent implementations that are currently used in the
   operational Internet. They are:

      - cisco. This implementation was wholly developed by cisco.
        It runs on the proprietary operating system used by the
        cisco routers. Consult Kirk Lougheed ([e-mail])
        for more details.

      - "gated". This implementation was developed wholly by Jeff
        Honig ([e-mail]) and Dennis Ferguson
        ([e-mail]).  It runs on a variety of operating systems
        (4.3 BSD, AIX, etc...).  It is the only available public domain
        code for BGP. Consult Jeff Honig or Dennis Ferguson for more
        details.

      - NSFNET. This implementation was developed wholly by Yakov
        Rekhter ([e-mail]). It runs on the T1 NSFNET
        Backbone and T3 NSFNET Backbone. Consult Yakov Rekhter for
        more details.

   To facilitate efficient BGP implementations, and avoid commonly made
   mistakes, the implementation experience with BGP in "gated" was
   documented as part of RFC 1164.  Implementors are strongly encouraged
   to follow the implementation suggestions outlined in that document.

   Experience with implementing BGP showed that the protocol is
   relatively simple to implement. On the average BGP implementation
   takes about 1 man/month effort.



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RFC 1266            Experience with the BGP Protocol        October 1991


   Note that, as required by the IAB/IESG for Draft Standard status,
   there are multiple interoperable completely independent
   implementations, namely those from cisco, "gated", and IBM.

8. Operational experience.

   This section discusses operational experience with BGP.

   BGP has been used in the production environment since 1989.  This use
   involves all three implementations listed above.  Production use of
   BGP includes utilization of all significant features of the protocol.
   The present production environment, where BGP is used as the inter-
   autonomous system routing protocol, is highly heterogeneous.  In
   terms of the link bandwidth it varies from 56 Kbits/sec to 45
   Mbits/sec. In terms of the actual routes that run BGP it ranges from
   a relatively slow performance PC/RT to a very high performance
   RS/6000, and includes both the special purpose routers (cisco) and
   the general purpose workstations running UNIX. In terms of the actual
   topologies it varies from a very sparse (spanning tree or a ring of
   CA*Net) to a quite dense (T1 or T3 NSFNET Backbones).

   At the time of this writing BGP is used as an inter-autonomous system
   routing protocol between the following autonomous systems: CA*Net, T1
   NSFNET Backbone, T3 NSFNET Backbone, T3 NSFNET Test Network, CICNET,
   MERIT, and PSC. Within CA*Net there are 10 border routers
   participating in BGP. Within T1 NSFNET Backbone there are 20 border
   routers participating in BGP. Within T3 NSFNET Backbone there are 15
   border routers participating in BGP. Within T3 NSFNET Test Network
   there are 7 border routers participating in BGP. Within CICNET there
   are 2 border routers participating in BGP. Within MERIT there is 1
   border router participating in BGP. Within PSC there is 1 router
   participating in BGP. All together there are 56 border routers
   spanning 7 autonomous systems that are running BGP.  Out of these, 49
   border routers that span 6 autonomous systems are part of the
   operational Internet.

   BGP is used both for the exchange of routing information between a
   transit and a stub autonomous system, and for the exchange of routing
   information between multiple transit autonomous systems. It covers
   both the Backbones (CA*Net, T1 NSFNET Backbone, T3 NSFNET Backbone),
   and the Regional Networks (PSC, MERIT).

   Within CA*Net, T3 NSFNET Backbone, and T3 NSFNET Test Network BGP is
   used as the exclusive carrier of the exterior routing information
   both between the autonomous systems that correspond to the above
   networks, and with the autonomous system of each network. At the time
   of this writing within the T1 NSFNET Backbone BGP is used together
   with the NSFNET Backbone Interior Routing Protocol to carry the



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RFC 1266            Experience with the BGP Protocol        October 1991


   exterior routing information. T1 NSFNET Backbone is in the process of
   moving toward carrying the exterior routing information exclusively
   by BGP.  The full set of exterior routes that is carried by BGP is
   well over 2,000 networks.

   Operational experience described above involved multi-vendor
   deployment (cisco, "gated", and NSFNET).

   Specific details of the operational experience with BGP in the NSFNET
   were presented at the Twentieth IETF meeting (March 11-15, 1991, St.
   Louis) by Susan Hares (MERIT/NSFNET).  Specific details of the
   operational experience with BGP in the CA*Net were presented at the
   Twentieth IETF meeting (March 11-15, 1991, St. Louis) by Dennis
   Ferguson (University of Toronto).  Both of these presentations are
   available in the IETF Proceedings.

   Operational experience with BGP exercised all basic features of the
   protocol, including the authentication and routing loop suppression.

   Bandwidth consumed by BGP has been measured at the interconnection
   points between CA*Net and T1 NSFNET Backbone. The results of these
   measurements were presented by Dennis Ferguson during the last IETF,
   and are available from the IETF Proceedings. These results showed
   clear superiority of BGP as compared with EGP in the area of