Cogent/Level 3 depeering

Wed Oct 5 20:57:54 UTC 2005

Justin M. Streiner wrote:

> Remember that when backbones peer with each other, they typically (and 
> as normally dictated by peering policies on both sides) only announce 
> their own routes and the routes of their downstream customers and agree 
> not to announce a default route to each other.  They do not announce a 
> full routing table to each other.  Upshot: When provider X de-peers 
> provider Y, single-homed customers of either provider will likely have 
> problems reaching single-homed sites of the other.

That assumes that both are transit-free networks.  We've already heard 
that Cogent buys some form of fill-in transit from Verio, perhaps for a 
subset of {AOL/ATDN, Sprint, others}.  Assuming such, why aren't routes 
appearing in L3's routers with paths matching _2914_174_?  L3 might be 
filtering them out (automatically or manually; perhaps filters haven't 
auto-generated yet), or Cogent might be requesting that they be filtered 
(Verio's community structure allows this quite easily).  Conversely, why 
aren't routes appearing in Cogent's routers with paths matching 
_2914_3356_?  If Cogent is buying transit from Verio, they should be 
receiving a full table.

Anyone have any inside connections to expose the truth(s) here?

pt