Ethernet TCP/IP broadcasts: help


jmg (jmg%CERNVAX.BITNET@wiscvm.wisc.edu)
3 Apr 87 15:29:37 GMT


Last Wednesday (yes, it was April 1st; no it was NO JOKE) we got a
situation on our Ethernet where a particular telnet RST packet from
a host to a client was being sent inside a broadcast packet. The
trouble was that this same broadcast packet was being sent out repeatedly
by just about every TCP/IP host on our Ethernet (including both VMS
with Wollongong and 4.2BSD). Thus, we were seeing about 1000 broadcast
packets per second, coming from many diffferent sources but all containing
this same RST information. This was, of course, killing all the small
microvaxes and weaker 750/780 etc., with only the big 8800 having enough
clout to continue apparently normally.

We eventually stopped it by disconnecting all of the offenders, much
to their disgust. After that everything started fine.

Since we started installing Ethernet some years ago we have never seen
such a catastrophic situation. Therefore, if anyone has any idea why
so many vaxes should start rebroadcasting packets which were nothing
to do with them I should be eternally grateful.

Mike Gerard



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