[ih] Global congestion collapse

Perry E. Metzger perry at piermont.com
Mon Dec 13 18:32:02 PST 2004


"David L. Mills" <mills at udel.edu> writes:
> Well, if your incident was during 1986-1988 and involved transit of
> the NSFnet Phase-I backbone, I'm the perp. The NSFnet routers ran my
> code, which was horribly overrun by supercomputer traffic. I found the
> best way to deal with the problem was to find the supercomputer
> elephants and shoot them. More is in a 1988 SIGCOMM Symposium
> paper. More recently the USNO and NIST time servers are being overrun
> with NTP traffic. See my recent PTTI paper at
> www.eecis.udel.edu/+mills/papers.html.
>
> The NSFnet meltdown occured primarily because the fuzzball routers
> used smart interfaces that retransmitted when either an error occured
> or the receiver ran dry of buffers. The entire network locked up for a
> time because all the buffers in all six machines filled up with
> retransmit traffic and nothing could get in or out. As I recall, the
> ARPAnet also had a similar problem with reassembly buffers.

Interesting. Bellcore switched from a 56k link to the IMP at Columbia
to NSFnet towards the end (latter half?) of that time, but I can't
remember if the horrible congestion was before or after our switch.

Either way, though, it was pretty shortly thereafter that I remember
getting my first replacement .o files with yummy new TCP congestion
control algorithms in them.

Perry



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