[ppml] Effects of explosive routing table growth on ISP behavior
sleibrand at internap.com
Tue Oct 30 13:24:40 EDT 2007
Brian Dickson wrote:
> Scott Leibrand wrote:
>> Small ISPs have several options in addition to multihoming with full
>> BGP routes or singly homing. They can multihome with default only,
>> announcing their route(s) to the world, but doing their outbound TE
>> by some method other than BGP. They could accept partial routes plus
>> default, giving them a lot of the benefit of outbound BGP route
>> selection without having to take a full table. Or, they could
>> actively filter deaggregates, maintaining full BGP reachability
>> without having to keep up with their competitors' upgrade cycles.
> It's also not a problem limited to the smallest of ISPs.
> Having to replace significant portions of one's infrastructure, before
> that equipment has been amortized per one's business plan, is a very
> bad thing.
> And equipment costs are generally speaking proportional, for any size
> of ISP.
> Which is to say, even medium to large ISPs may find themselves in
> trouble (in some cases, again) if they have to replace equipment
> And medium-to-large ISPs are likely not to have the luxury of going
> single-homed, or of taking partial routes.
> (The last round of bankruptcies certainly wasn't limited to small
> ISPs, for example. Worldcom? PSInet? to name two biggish networks.)
Yes, explosive routing table growth would definitely a problem for
everyone taking full BGP routes. However, I think it's a problem that
can be addressed, if/when necessary, by requiring that everyone announce
their minimum-allocation-size covering aggregates, so that folks can
filter out unnecessary deaggregates. With that as an alternative, I
don't think routing table growth alone will push anyone into bankruptcy.
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