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From: LEICHTER-JERRY@YALE.ARPA
Newsgroups: comp.os.vms
Subject: Re: Ethernet LAT-Decserver-200 query : how is mnemonic/address info obtained?
Message-ID: <8706231009.AA03055@ucbvax.Berkeley.EDU>
Date: Tue, 23-Jun-87 06:09:20 EDT
Article-I.D.: ucbvax.8706231009.AA03055
Posted: Tue Jun 23 06:09:20 1987
Date-Received: Wed, 24-Jun-87 07:19:00 EDT
Sender: daemon@ucbvax.BERKELEY.EDU
Reply-To: <LEICHTER-JERRY@YALE.ARPA>
Distribution: world
Organization: The ARPA Internet
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    Where does a LAT terminal server obtain its menmonic/address information
     for services on the Ethernet other than those situated locally on the
     terminal server?...

    A few possibilities spring to mind.
    
     (4) Information is sent out a regular intervals.

[I've left out the incorrect possibilities - the author listed 7!]

The model LAT uses is that various nodes "offer services" that a given LAT
terminal server will then allow connections to.  The way a node "offers a
service" is to send out multicasts at regular intervals - default is every 20
seconds; this is a settable parameter -  describing what services it has to
offer.  All terminal servers listen for these multicasts and update their
service/address tables when they something new.  (I don't think terminal
servers ever remove a service from their tables until someone tries to connect
to it and the attempt fails, but I might be wrong on this.)

The multicast is a "node configuration message"; it describe such things as
the node's Ethernet address, the services offered, the groups the node is a
member of, and the node's current load rating.
							-- Jerry
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