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

Ted Mittelstaedt tedm at ipinc.net
Wed Oct 31 18:09:23 EDT 2007

>-----Original Message-----
>From: ppml-bounces at arin.net [mailto:ppml-bounces at arin.net]On Behalf Of
>Jason Schiller
>Sent: Wednesday, October 31, 2007 2:43 PM
>To: Scott Leibrand
>Cc: ppml at arin.net
>Subject: Re: [ppml] Effects of explosive routing table growth on ISP
>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.
>When routing slots become scarse we all will have the difficult decesion
>of which routes to install.  
>It is my suspicion that ISPs will discard non-customer routes first before
>customer routes.  The first set of routes likely to be discarded are
>non-customer routes that are a more specific of an aggregate.  This will
>break TE.  The next set of routes likely to be discarded are non-customer
>At this point, a paying customer may complain that it cannot reach some
>non-customer destination.  The ISP will explain that the destination in
>question is not a customer, and does not pay to have its route in the
>table.  The ISP will then offer the option for his or her customer to pay
>to have the route in the table, or the destination can pay to thave their
>route in the ISp's table. 

My guess is if this kind of thing ever came to pass you would see some
kind of "dynamic filtering" come into place.  In other words, the ISP's
BGP peer router would look at ALL inbound and outbound traffic that
passes through it, and automatically modify the filter to allow the
route into the table for any source or destination of any packet going
through the router.  You would set the expiration of the "hole" in the
filter to be proportional to the number and size of the packets and
how long they were coming through the hole.

Oh dear, I've probably done gone and screwed up someone's patent

But I still think that a lot of this is chicken little stuff.  Think
of how many credit card numbers there are in the world, and how any
of them could suddenly appear at some card swipe machine anywhere in
the world, yet the global banking community seems to be able to
handle this just fine.  The hardware exists to do that, it can be built
to do this.


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