RFC 1656 (rfc1656) - Page 2 of 4

BGP-4 Protocol Document Roadmap and Implementation Experience

RFC 1656                  BGP-4 Implementation                 July 1994


        ANS (gated)
        Europanet
        3COM
        cisco

   The complete interoperability matrix between all known
   implementations of various versions of BGP is available under
   separate cover [9].

Implementation Testing

   One implementation has been extensively tested in a network designed
   to mirror the complex connectivity present at many major Internet
   borders.  This network consists of multiple BGP-3 and BGP-4 speakers
   carrying full routing information injected from Alternet, EBone,
   Sprint, CERFnet, and cisco.  In many cases additional AS adjacencies
   are simulated via the use of IP over IP tunnels to increase the
   complexity of the routing topology.

   The primary feature of BGP-4 is the ability to carry network
   reachability information without regard to classfull routing.  In
   addition to canonical routing information,  CIDR prefixes (both
   supernets and subnets) are being injected from IGP information and
   aggregated using the methods described in BGP-4.  AS set aggregation
   and policy decisions based upon AS sets have been tested.

   Secondary extensions incorporated as part of version 4 of this
   protocol include enhancements to use of the INTER_AS_METRIC (now
   called MULTI_EXIT_DISC), the addition of a LOCAL_PREF parameter to
   influence route selection within an AS,  and a specified method of
   damping route fluctuations.  All of these features have been tested
   in at least one implementation.

Observations

   All implementations, are able to carry and exchange network
   reachability information.

   Not all implementations are capable of generating aggregate
   information based upon the existence of more specific routes.

   No implementation supports automatic deaggregation (enumeration of
   all networks in an aggregate block for backwards compatibility with
   routing protocols that do not carry mask information (e.g. BGP-3)).
   However, most implementations do allow for staticly configured
   controlled deaggregation for minimal backwards compatibility with
   non-CIDR capable routers.




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