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From: mckee@MITRE.ARPA
Newsgroups: mod.protocols.tcp-ip
Subject: Gateway Selection Procedure
Message-ID: <8609041457.AA08219@mitre.ARPA>
Date: Sat, 6-Sep-86 05:02:54 EDT
Article-I.D.: mitre.8609041457.AA08219
Posted: Sat Sep  6 05:02:54 1986
Date-Received: Sat, 6-Sep-86 20:33:10 EDT
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Organization: The MITRE Corp., Washington, D.C.
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Approved: tcp-ip@sri-nic.arpa


Gentlemen:

I solicit advice and document references on how IP should select a
particular Gateway when more than one is available.

Background

My responsibilities include writing communications and network
performance requirements for a large military system called the WWMCCS
Information System (WIS).  The WIS will (initially) consist of about 40
sites.  Each site will have:
  
    - a 10 Mbps Applitek LAN

    - 2 or 3 large host processors

    - 50 to 150 workstations

The workstations and hosts are connected to the LAN through Interface
Units (IUs).  TCP and IP are performed in the IUs.

Each LAN has at least one Gateway IU that connects the LAN to the
DDN-RVN (DDN-Red Virtual Network, Class A Net 21).  All inter-site
communications use net 21.  For increased throughput and availability,
some sites will have 2 or 3 Gateway IUs.  Some Gateways will connect to
the DDN-RVN at 56 Kbps, others at 9.6 Kbps.

Each LAN has a LAN Control Center/Security Monitor (CC/SM).  For
security and access control, procedures have been established such that
the CC/SM is aware of the status of every connection; every TCP active
or passive open/close/abort request is routed through the CC/SM.
Further, by means of periodic interrogation, the CC/SM knows the health
and traffic load of every local IU, including the local Gateways.

Questions

When IP in a host or workstation IU receives a datagram destined for a
remote site, what procedure should be used to select one of the local 
Gateways?

When IP in a Gateway receives a datagram from the LAN, what procedure
should be used to select one of the Gateways at the remote site?

Any advice or references would be appreciated.

H. Craig McKee
'mckee at mitre'
(703)883-5505