Re: Why is the ARPANet in such bad shape these days?


Dennis G. Perry (PERRY@VAX.DARPA.MIL)
Sun 28 Sep 86 22:10:54-EDT


I can shed a few ray of light (or is that tears) on the Arpanet
congestion problem. I don't guarentee that I fully understand the issues,
since I believe we have an onion problem. The E-W problem seems to be
related to the fact that there are only two E-W lines, both running
on average about 60% utilization. In fact, they occilate between
20 and 90% utilization. Instability occurs when lines become saturated
and the network starts hunting. Another congestion problem in the
PSNs is the multi-packet message. Apparently there is not enough
buffer space to allocate all the buffers needed to support the current
multi-packet message traffic. The net result is to paralyze the network,
as each PSN quits accepting incomming multi-packet messages.

There may be other problems as well. We are working on solutions, but
as indicated, it may take a while.

dennis
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