AOL & Cogent

Jeff S Wheeler jsw at
Mon Dec 30 18:59:40 UTC 2002

On Mon, 2002-12-30 at 06:37, Basil Kruglov wrote:
> For my not-so-bright customers I simply want traceroutes to look good when
> they run one from Level3-homed site. Obviously a ~5-7 hops to us looks
> really disturbing, try to explain to one of them that there is no problem.
After some off-list discussion I think I understand the issue.  You do
not want customers who are doing a traceroute from Level3 or one of
their downstreams to see high latency on some of their traceroute hops
going toward you, because you cannot control the egress path of those
ttl_exceeded packets from cogent's network, even though you can control
your own egress.

So the obvious solution is to prepend your advertisements toward cogent,
which will cause them to carry less of your inbound traffic.  This has a
negative impact for cogent, because they need that inbound traffic to
justify some of their peering agreements (think, ratios).  Supposedly
this is the reason they couldn't keep the ATDN peering, eh?  If all
their web host-type customers suddenly start prepending advertisements,
it will cause them to bleed inbound traffic.

If you want to encourage cogent to build a rich community set so you can
prepend only toward Level3, perhaps you should start prepending toward
cogent and make the point with your cogent rep that this is going to
cause them to lose your inbound traffic, and if they gave you more
control over route advertisements, it would not have such an impact.

On the other hand, maybe cogent doesn't want web hosts as customers. :-)

Jeff S Wheeler <jsw at>

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