North American Network Operators Group

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Re: Cogent/Level 3 depeering

  • From: Todd Vierling
  • Date: Wed Oct 05 13:43:05 2005

On Wed, 5 Oct 2005, Matthew Crocker wrote:

> > I'm curious where in your contract you think Cogent guaranteed you
> > connectivity to Level 3?
> My original contract was with NTT/Verio which Cogent purchased last year when
> Verio nuked their Boston POP.   I'm having the contract dug out of the
> archives to look at what it says.  IMHO  I pay Cogent for Transit to the whole
> Internet,  If I wanted partial transit or local peering I would order/contract
> and pay for that.   Cogent is not currently providing me full transit service.
> I really don't care who pulled the plug, it is Cogents job to fix it for me as
> I am their customer.

"Isn't BGP supposed to work around this sort of thing?"

This comes down to a little more than just "depeering" -- at least in the
BGP sense.  There's active route filtering going on as well if connectivity
is dead; after all, I can bet the house that at least one of Cogent's
network edge peers has connectivity to Level3, and vice versa.

>From where I sit, I can see a plethora of routes that transit more than one
tier1.  And a few that transit three before hitting the origin.  From a
couple locations I see 3356 and 174 visible in *all* paths to the prefixes
containing Level3 and Cogent in the path, respectively.

So perhaps the question you should be asking is:  Why didn't routes for
these networks fall over to the other upstream peers which *are* capable of
moving the packets?  Surely MCI, AT&T, Sprint, and others would carry the
packets to the right place.  I can see the paths right here....

> > Most transit contracts only guarantee packet delivery to the edge of their
> > own networks.  I'm pretty sure Cogent is doing that.  (Hell, they have lots
> > of spare capacity now. :)
> Most also have a clause to cover the inter-AS links, making sure that they are
> not overloaded.

What nature of clause?  I consider deliberately filtering prefixes or origin
ASs to be a violation of common backbone BGP use.

Too bad there aren't Equal Access laws for tier1s.  <slyly evil grin>

-- Todd Vierling <[email protected]> <[email protected]> <[email protected]>