Re: Network Connectivity - Part 2

Frederick E Serr BBNCC 20/666 x2474 (fserr@ALEXANDER.BBN.COM)
Fri, 04 Nov 88 12:09:39 -0500

I would urge TOPS-20 administrators NOT to add more than one or two
other gateways to their gateways file, if any. The MILNET Mailbridge
Gateways were explicitly turned off yesterday to slow the spread of
the virus. As you yourself said, their normal reliability is such
that one primary gateway and one backup entry was enough to keep
your host "connected" for several years without running into this
problem. Presumably, turning off the Mailbridges because of external
circumstances will continue to be a rare event.

The reason for only having one or two entries in the file in the first
place is to reduce the amount of ICMP overhead traffic on Arpanet and
Milnet. TOPS-20s periodically "ping" all the gateways on their list.
A few years back, this was adding up to a substantial fraction of all
the traffic on the Arpanet. While one can argue that adding one more
gateway to one host will result in only a small amount of traffic, it
still seems worth avoiding, when the problem one is fixing is so rare.

Fred Serr
Network Analysis Dept.
BBN Communications

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