On Sun, 23 Sep 2007 michael.dillon@bt.com wrote:
Has everyone forgotten the "Tier 1 depeerings" of several years ago? i.e. If you were pointing default at C&W, PSINet, Cogent, or Level3 when they each had or caused depeering issues, parts of the internet ceased to be reachable. In such cases, having full routes from multiple providers was the only way to be automatically protected from such games.
Not so. Anyone who had sufficient transit was also protected from the games. Lots of so-called regionals and tier-2 networks were shielded from this monkey-business. And, of course, they shielded their customers as well. A tier-1 network operator who operates such a fragile network becomes a single point of failure. And not just because of peering as the AT&T frame relay collapse shows.
I think you've completely missed what I said. If you were pointing default at C&W (whether they were your only connection, or you were "multihomed" but couldn't handle full routes, so perhaps you had customer routes from each provider and default pointing at C&W) when they depeered PSI, single homed (or similarly configured non-full routes) customers of PSI ceased to be reachable. A long time customer of mine was hit by this (their business required communications with one or more single homed PSI customers, and C&W was their sole transit). It was the driving force behind their multihoming. Ever since, they've maintained 3 or more transit providers and full routes from each. ---------------------------------------------------------------------- Jon Lewis | I route Senior Network Engineer | therefore you are Atlantic Net | _________ http://www.lewis.org/~jlewis/pgp for PGP public key_________