Route table growth and hardware limits...talk to the filter

Sat Sep 8 11:51:02 UTC 2007

On Sat, 8 Sep 2007, Lincoln Dale wrote:

> what i think it boils down to is that many folks seem to run default-free
> because they can, because its cool, because its what tier-1 folks do, because
> (insert cool/uber reason why here), but not necessarily because they HAVE TO.

Consider a regional or local ISP providing BGP to a customer.  The 
customer also has a connection to a "Tier 1".  The customer may start 
asking questions when they notice they get 250k routes from one provider 
and only 50k to 80k less routes from you.

I suppose some "Tier 1"s got away with this in the past though...so maybe 
there are acceptable answers.

> even if you're a content-provider in North America and want to ensure an
> "optimal path" of traffic, generally speaking, you could accept prefixes
> (as-is) from ARIN allocations but for (say) APNIC and RIPE do either some
> degree of filtering or just push it via a default.

I actually suggested this yesterday to a friend who runs an ISP and has 
just run into his 7500s running out of RAM and crashing when turning up a 
new transit provider with full BGP routes.  Filtering the APNIC and RIPE 
regions and adding a default will very likely let him fit "mostly full 
routes" on his router and put off the inevitible fork-lift upgrade a 
while longer.

----------------------------------------------------------------------
  Jon Lewis                   |  I route
  Senior Network Engineer     |  therefore you are
  Atlantic Net                |
_________ http://www.lewis.org/~jlewis/pgp for PGP public key_________