Backbone-News

Exactly 14 days after the “dispute” between Cogent and Telia started, it seems that both parties have finally reached an agreement.

Since 17:53 UTC today, there is again direct connectivity between both networks, and as a consequence customers on both networks can reach each others again.

Below is the view of the connectivity of one of the Cogent prefixes (38.0.0.0/8) as it was seen again today. (Click on the image for a larger version)

We did some test using the Cogent Looking Glass, and we can see that connectivity between both networks has been restored at multiple locations in the US and Europe.

Traceroute from Washington towards www.teliasonera.se:

 1 fa0-8.na01.b005944-0.dca01.atlas.cogentco.com (66.250.56.189) 4 msec 4 msec 0 msec
  2 gi3-9.3507.core01.dca01.atlas.cogentco.com (66.28.67.225) 4 msec 4 msec 4 msec
  3 te3-1.ccr02.dca01.atlas.cogentco.com (154.54.3.158) 4 msec 4 msec 0 msec
  4 vl3493.mpd01.dca02.atlas.cogentco.com (154.54.7.230) 4 msec
    te4-1.mpd01.dca02.atlas.cogentco.com (154.54.2.182) 0 msec 0 msec
  5 vl3494.mpd01.iad01.atlas.cogentco.com (154.54.5.42) 0 msec
    vl3497.mpd01.iad01.atlas.cogentco.com (154.54.5.66) 0 msec 4 msec
  6 ash-bb1-geth7-3-3-0.telia.net (213.248.88.41) 4 msec 4 msec 4 msec
  7 nyk-bb2-link.telia.net (80.91.250.18) 8 msec
    nyk-bb2-pos0-3-0.telia.net (213.248.80.137) 12 msec
    nyk-bb1-link.telia.net (213.248.83.21) 8 msec

Hop 6 is the first hop on the TeliaSonera network and the hostanme identifies this as Ashburn/US.

Traceroute from Los Angeles:

  1 gi10-0.224.core01.lax01.atlas.cogentco.com (66.250.4.5) 0 msec 4 msec 4 msec
  2 te3-1.mpd01.lax01.atlas.cogentco.com (154.54.2.102) 0 msec 0 msec 4 msec
  3 vl3492.mpd01.lax05.atlas.cogentco.com (154.54.3.10) 0 msec
    vl3493.mpd01.lax05.atlas.cogentco.com (154.54.6.230) 0 msec 0 msec
  4 gi0-0-0.core01.lax05.atlas.cogentco.com (154.54.6.185) 4 msec 4 msec 0 msec
  5 las-bb1-link.telia.net (213.248.72.177) 4 msec 4 msec 4 msec
  6 nyk-bb1-link.telia.net (80.91.254.18) 76 msec 72 msec 72 msec
  7 kbn-bb1-link.telia.net (80.91.249.25) 168 msec 172 msec 168 msec
  8 s-bb1-link.telia.net (213.248.65.141) 172 msec 176 msec 176 msec
  9 s-b4-link.telia.net (80.91.251.21) 176 msec 176 msec 176 msec

Hop 5 shows us the second interconnect in the US, located in LA.

Traceroute from Amsterdam:

 1 vl3.mpd01.ams03.atlas.cogentco.com (130.117.16.125) 0 msec 0 msec 4 msec
  2 gi2-0-0.core01.ams03.atlas.cogentco.com (130.117.0.33) 0 msec 0 msec 4 msec
  3 po1-0.core01.lon01.atlas.cogentco.com (130.117.1.225) 68 msec 220 msec 228 msec
  4 ldn-b4-link.telia.net (213.248.70.237) 8 msec 8 msec 12 msec
  5 ldn-bb1-link.telia.net (80.91.251.18) 8 msec
    ldn-bb1-link.telia.net (80.91.250.234) 8 msec 24 msec
  6 hbg-bb1-link.telia.net (80.91.250.220) 24 msec
    hbg-bb2-link.telia.net (80.91.254.218) 24 msec 24 msec

Hop 4 is the first router on the TeliaSonera network. This time located in London/UK.

Traceroute tests from the other Cogent routers in Europe all go through London, even from Stockholm, indicating that we London is the only interconnect between the two networks in Europe.

Until last Friday, Cogent and TeliaSonera were in a bilateral peering relationship, meaning they exchanged traffic between their networks for free.

By what is known at the moment, it looks like Cogent is at the origin of the problem. They have decided to end the peering agreement no longer exchange traffic with TeliaSonera. The consequence is that people with Cogent only connectivity are no longer able to connect to sites on teh telia network, and vice-versa.

There is no official word yet from Cogent, but Telia has informed their customers and blames Cogent. Funny enough they basically recommend to their Transit customers to buy additional Upstream from a second ISP to get around the issue. Interesting approach.

It isn’t the first time that Cogent finds itself in a peering fight. In 2005 Level3 de-peered Cogent, the same year OpenTransit de-peered Cogent and I could continue to go on.

It shows unfortunately yet again one thing: Don’t rely on a single provider if you want reliable connectivity! get multihomed to at least to different Transit providers!

We will provide you with more updates on the current situation as soon as further details appear.

Further coverage:
GigaOm
Nanog