[nSLUG] Problems with Eastlink Hosting Multiple IPs on One Network Interface

RickF @ Transpect rickf at transpect.net
Tue Nov 15 01:52:00 AST 2005

Jason Kenney wrote:

> I don't have a static IP, just the regular residential service, but
> I've noticed another problem for at least two months now.
> It has been much better this week however, and I haven't seen the
> usual strange behaviour:
> - Failure to open any new connections, except to peers for about 5-10
> minutes.
> For example, my MSN Messenger would continue to work correctly, but
> any website I tried to visit would just time out (the DNS would
> resolve though). I could however get to any of Dalhousie. (But not
> cnn.com, etc.)
> A temporarily outdated or not updating ARP table somewhere up their
> line might explain this I guess. I know at least three other people on
> different subnets who had the same problem, but I haven't heard any
> complains in the last couple days, so maybe it's been fixed.
> I had a theory it might have been due to poorly implemented traffic
> shaping, but this was hard to test, and unclear. It was clear it was
> something in Eastlink, since everywhere else died, but proxying
> through Dal worked fine.
> Maybe it's related. *shrug*

One thing I have noticed is the immense amount of ARP traffic that gets
passed around. Even when no traffic whatsoever is coming or going from
my boxes, there's at least a good 10-15k/s of purely ARP traffic, the
vast majority being requests. Try doing a tcpdump of it sometime, it's

I don't know how they have their network set up, but that seems a little
wacky to me. Perhaps some sort of scanning utility?


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