[ih] Somebody probably asked before - Trying to remember early net routing collapse

[Karl Auerbach]

I am sure this has been discussed, but I can't seem to find it...

I vaguely remember a story involving some of Dave Mills' machines and a 
memory error in IMPs or some other switching device that caused all of 
the net's traffic to be forwarded through one struggling Fuzzy* or 
PDP-11/03.

Could someone give me a pointer?

I once did something similar - back when we were using flood-and-prune 
routing for IP multicast, I was working at a site where our inbound link 
was a T-1.  Our internal net had several Cisco routers [2500 series] all 
chatting away with DVMRP [the flood-and-prune multicast routing protocol 
of that era.]  Anyway, while I was setting up one or our internal 25xx 
routers I had not yet finished setting up the IP unicast routing.  But 
that didn't stop my partially configured router from chatting away with 
IGMP and DVMRP, it merely meant that that router could not send the 
"prune, please stop sending me traffic!" message.

So that router eventually ended up at the end of every IP multicast 
"flood" that was active on the MBone but without a way of saying "stop, 
please stop!".  Our poor T-1 saturated.  I learned to not enable IP 
multicast via DVMRP until my unicast routing was stable.  (We eventually 
moved onto PIM for multicast routing.)

     --karl--