To set the record straight, no peering agreements were violated
between L3 and Cogent.

I heard otherwise, however I can't prove that.

>There is also no confirmed evidence that L3 is
blocking Cogent traffic through Cogent's Verio transit (which Cogent
pays $$ for.)

There was evidence. I wish I saved my traceroutes yesterday.
To make more clear, Cogent is our backbone.
When going to, the last successfull hop was a peer labelled similar to, meaning we crossed over to Verio's side. (the actual name was more meaningful). Now today, the traffic destined for that site stops cold at the first hop from our network, meaning it does not get routes from Level3 on where to send the data, once we enter Cogent's network. Unless you are referring that Cogent is blocking any advertised route info from Level3, which is highly unlikely. If Level3 was allowing our IPs to go through Verio's link, we would receive routes to route our packets in that direction across Cogent's network, and packets would travel further into Cogent's network (such as to the Verio link). If Cogent blocked traffic to Verio, it would most likely block it at the peer, not at the entry to Cogent's network from us as their client.

It appears that Cogent is unwilling to use this route
because it would force them to pay (Verio) per Mb/s for the
information sent to/from L3's network.  The de-peering was consistent
with the peering agreement between L3 and Cogent according to

It stated that, but it is not in actuallity.

Current NANOG consensus (whatever that's worth) is that both companies
are equally responsible for correcting their reachability issues, but
L3 initiated the de-peering process.

Agreed. UNLESS Level3 is actually blocking IPs that were assigned via Cogent apposed to just blocking routes or connections. Unfortuneately I am not in a possition to prove wether our IPs are blocked because we are still single homed with Cogent. Cogent has so many peers that could transmit our data via alternate paths, and the amount of traffic on our network going to level 3 is so little, that Cogent would be making a poor financial decission not to route our traffic an alternate path based on risking that we would switch to a redundant link to Level3. Its not to Cogent's benefit to not route our traffic financial, so it is only logical that it is Level3 blocking our IPs. I was also told Level3 was blocking our IPs, which is why our IPs could not be re-routed. Sure I can't prove this, but its not looking good for level-3.

Peering (or Settlement Free Interconnection, SFI) is an extremely
complicated subject often involving millions of dollars to the
carriers involved.  The current NANOG thread on the subject contains a
great deal of information (and mis-information) and is a good read for
those interested in the subject.  I tend to weight the arguments made
by Patrick, Leo, Randy, Vijay, and Richard higher than most others.


On 10/6/2005 11:16 AM, Tom DeReggi created:
For those that are not aware, Level-3 vilolated its inplace agreements,
and blocked all peering connections from Cogent communications yesterday
(October 5th), and rumor has it that they are also now blocking all
Cogent assigned IP ranges, so that routing diverse paths won't be
effective.  Not much I can say about peering disputes, but blocking IPs
without cause (meaning violation of AUP) is crossing the line, and
clearly anti-competitive and a law sute soon to happen.

Level3 VOIP provider just lost our business over this one.  Can't risk
using a provider that demonstrates such practices.

If using Level3 for servers, call to complain, because otherwise you are
going to have lots of unsatisfied customers that can't get to the
servers that reside on the Cogent network. Level 3 is doing the blocking.

For those of you using Level3 and looking to become multi-homed, nows
the chance to save.  Cogent is offering FREE one years transit service
at the same capacity as the level 3 connection.

Tom DeReggi
RapidDSL & Wireless, Inc
IntAirNet- Fixed Wireless Broadband

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