Peering Wars

This was actually a quite old story issued by Renesys several months ago and it was also presented at NANOG 43 (June 2008). The story took a case of network-depeering and the actors were Cogent and Telia. At that time, both Cogent and Telia are considered as "near" Tier-1 providers. Why "near"?

• Cogent gets (got?) transit from NTT (formerly Verio) to reach AOL (ATDN?).
• Telia appeared to get transit from Verizon to reach certain networks.

Additionally, it is worth to mention that

• Tier-1 providers act like a cartel and have no incentive to add members
• "Near" Tier-1 providers can try to buy their way into the club (via "paid peering")

Renesys said that Cogent and Telia want to be "real" Tier-1, and from this point, the story began:

• On 27/Feb/2008 Renesys stopped seeing evidence of Telia's transit routes and Renesys promotes Telia to "Tier-1" (However, it could still be paying for some of these interconnections)
• On 13/03/2008 Cogent depeers Telia, claiming breach of contract; Renesys observes routes from Telia to Cogent via Verizon for 12 hours, these routes then disappear, partitioning the Internet for some single homed customers behind Cogent and Telia (they could not reach one another)
• On 28/03/2008, peering link is restored and the Internet is once again whole!

Renesys's Analysis
The following statements are taken (almost) entirely from Renesys.

Why did this happen?

• The peering disputes (Telia-Cogent) tend to be about peering ratios; i.e. one party is carrying the other's traffic longer distances
• Did Cogent view Telia as in a weaker position? (How many European customers want to reach Cogent hosted content?)

Facts after peering link has been restored:

• Number of routes advertised to Telia is increased; Telia reaches 2934 more prefixes via Cogent
• Number of routes advertised to Cogent is decreased; Cogent reaches 635 fewer prefixes via Telia

"This was the result of reengineering by both parties. It surely seems like this was about traffic ratios"

Lessons learned

• Being a (near) Tier-1 is not easy; you depend on everyone else in the cartel and you will be punished if you are perceived to be in a position of weakness
• Peering relationships are tricky; depend on both objective measures and perceptions; disputes can take a long time to resolve; the only driver is market pressure
• Being single-homed is dangerous!

Other notes

• An increasing number of businesses and organizations are now multi-homed
• Many more peering relationships, lessening the impact of any one loss
• True global Tier-1s would probably never consider depeering; impact would be wide ranging; it would invite government involvement
• Tier-1s are becoming less relevant, as smaller players peer around them (This shall be the reasons, why Tier-1s have always to defend their positions with expanding their coverage and acquire new customers !!)

Credits: Renesys Corp. (Martin A. Brown; Alin Popescu; Earl Zmijewski)