Network Working Group                                         Jon Postel
Request for Comments: 890                                            ISI
                                                           February 1984

Status of this Memo

   This memo is a policy statement on the implementation of the Exterior
   Gateway Protocol in the Internet.  This is an official policy
   statement of ICCB and DARPA.

The Current Situation

   Currently the Internet has a number of smart gateways and a number of
   dumb gateways.  The smart gateways dynamically exchange routing
   information among themselves using the Gateway Gateway
   Protocol (GGP) [3].  The dumb gateways do not exchange routing
   information dynamically.

   The dumb gateways must be listed in the smart gateway routing tables,
   and changes in dumb gateways status (e.g., adding new dumb gateways)
   in the smart gateways tables requires human intervention.

   The amount of routing traffic between smart gateways depends on the
   number of smart gateways and the total number of networks.  Since
   dumb gateways typically connect a single network at the edge of the
   Internet, there is typically one more network in the routing table
   for each dumb gateway.

   Gateways that connect a single network to the edge of the Internet
   may be called "stub" gateways.

   The current GGP procedures used by the smart gateways are at the
   limits of their capacity.  A significant change to these procedures
   is urgently required.  This is difficult to perform because the smart
   gateways are maintained by several different groups, and because it
   is difficult to isolate a subset of these gateways for testing new
   procedures.

The Future Situation

   In the future, as it is currently envisioned, there will be a number
   of co-equal autonomous systems of gateways.  Each as will have its
   own private internal procedures for maintaining routing information,
   perhaps via an Interior Gateway Protocol (IGP).  The smartness of a
   gateway will be the smartness of the IGP used in the autonomous
   system the gateway participates in.  Some gateways of each autonomous
   system will exchange routing informations with some gateways of other
   autonomous systems via an Exterior Gateway Protocol (EGP) [2].


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RFC 890                                                    February 1984
EGP Implementation Schedule


   The factoring of the old set of smart gateways into a number of
   autonomous systems allows more flexibility for the development and
   testing of improved routing procedures.  Different autonomous systems
   can adopt different routing procedures internally, as long as they
   communicate with other autonomous systems via the EGP.

The Transition Situation

   The first step in the transition from the current situation to the
   future situation is the replacement of all dumb gateways with
   gateways that implement at least a subset of the EGP.

      This subset is called the "Stub Exterior Gateway Protocol", and is
      described in RFC-888 [1].

   The second step is to factor the existing smart gateways into
   autonomous systems.  The gateways programmed and maintained by
   different groups will become distinct autonomous systems.  As things
   are, this will result in one fairly large autonomous system and three
   or four small autonomous systems.  At this step the large autonomous
   system will be referred to as the "core" autonomous system.  All
   other autonomous systems will be stubs attached to this core via EGP.

   The third step is to specify the full EGP protocol, and to allow a
   rich connectivity between co-equal autonomous systems.

Policy Statement

   After 1-Aug-84 there shall be no dumb gateways in the Internet.
   Every gateway must be a member of some autonomous system.  Some
   gateway of each autonomous system must exchange routing information
   with some gateway of the core autonomous system using the Exterior
   Gateway Protocol.

Implication

   If you have a dumb gateway now, you should start doing something
   today to get it upgraded to, or replaced by, an EGP gateway.

Help Available

   There may be a gateway you can use already developed by someone.
   People at the following places are working on EGP gateways:  BBN,
   MIT, Linkabit, ISI, Honeywell, and Symbolics.  For more information
   send a message to Joyce Reynolds at mailbox "JKReynolds@USC-ISIF".

   There are plans to provide EGP functionality in Berkeley 4.2 Unix.


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RFC 890                                                    February 1984
EGP Implementation Schedule


   Berkeley has indicated an intention to have EGP capability available
   in the standard release of 4.2 Unix before the cut off date for dumb
   gateways.

   The is a mailing list for EGP implementers called "egp-people".  To
   get on or off this list send a message to the mailbox
   "egp-people-request@BBN-UNIX".

   There is a EGP testing program available on TOPS20.  For information
   about using it send a message to Jim Mathis at mailbox
   "Mathis@SRI-KL".

   If you need an autonomous system number send a request to Joyce
   Reynolds at mailbox "JKReynolds@USC-ISIF".

References

   [1]  Seamonson, L., and E. Rosen, "Stub Exterior Gateway Protocol",
        RFC-888, BBN Communications Company, January 1984.

   [2]  Rosen, E., "Exterior Gateway Protocol", RFC-827, Bolt Beranek
        and Newman, October 1982.

   [3]  Hinden, R., and A. Sheltzer, "The DARPA Internet Gateway",
        RFC-823, Bolt Beranek and Newman, September 1982.
























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