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Re: It's Alive

    Date: Thu, 21 Sep 89 16:25:41 EST
    From: bouma@cs.purdue.edu

    Yes, the "phantom" machine is indeed a gateway. The people who maintain
    the unix boxes around here periodically run this thing that monitors
    network traffic. When this happens I get a message telling me to stop
    the lisp machines from sending out useless packets to a non-existent
    machine. The symbolics' must keep trying to contact the gateway to see
    if it has come up. Why don't they just wait until I try sending something
    through the gateway?

The current implementation of IP routing is primitive.  The IP Background code
periodically (once per minute) sends an ICMP echo to all the gateways to see
if they are still alive.  If a gateway that was up does not respond after a
number of pings, it is marked dead and all the routes through it are
recomputed.  This method is common to other IP implementations.  I believe the
intent is that ICMP echos are fairly inexpensive and it saves time so you
don't have to try dead gateways whenever you wish to access anything off the
local net.

    Thanks for everyone's input. When does 7.4 get released?

7.4 is only available for Ivory based machines.  The next release of Genera
will be for 3600s and Ivories.  It is currently scheduled for release late in
the first calendar quarter of 1990.