North American Network Operators Group
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Re: Level 3's side of the story

  • From: Patrick W. Gilmore
  • Date: Sat Oct 08 16:38:33 2005 
On Oct 8, 2005, at 3:07 PM, Richard A Steenbergen wrote:
Teleglobe depeers Cogent due to various ratio and market pressure issues.
Of note is that Cogent has recently entered the Canadian market where
Teleglobe has a strong presence, and has started giving away free or
nearly free transit to large inbound networks. Teleglobe is a Sprint
customer, and Cogent reaches Sprint through Verio. Teleglobe is caught
completely off-guard when Cogent refuses to accept the route via Sprint
transit, and blocks traffic between the networks. This continues for
several days, until eventually routes are leaked/added from Teleglobe to
SAVVIS (AS3561), who Cogent peers with. This continues for a few days more
until Teleglobe finally agrees to repeer Cogent.
[SNIP]

You mention at least twice (here and in the FT depeering paragraph) that Cogent "accepts" the routes.

It is entirely possible, and in fact likely IMHO, that the prefixes were never offered by Verio to Cogent. Cogent pays Verio for partial transit, why would Verio give Cogent more ASes than they paid for? If Verio doesn't announce the prefixes, how can Cogent filter them?

Of course, I do not have enable on Cogent or Verio border routers, so I cannot say for certain. Would anyone who _knows_ care to enlighten us?

--
TTFN,
patrick