Route table growth and hardware to the filter

Jon Lewis jlewis at
Sun Sep 23 15:23:01 UTC 2007

On Sun, 23 Sep 2007 michael.dillon at 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                |
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