[ppml] Effects of explosive routing table growth on ISP behavior

Brian Dickson briand at ca.afilias.info
Tue Oct 30 12:58:51 EDT 2007

Scott Leibrand wrote:
> Ted Mittelstaedt wrote:
>> It's unlikely that if the routing
>> table grows past existing ISP equipment that it would result in
>> ISP bankruptcies.  A far more likely scenario among the smaller
>> cash-poor ISP's is it will encourage single homing with the resultant
>> lowering of Internet reliability for customers of those ISPs.
> Even that is a bit of a false binary dichotomy.  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.
> -Scott
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 

And equipment costs are generally speaking proportional, for any size of 

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.)


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