Re: A tunneling proposal

["Jon (Taz) Mischo" <taz@tazlore.com>]

On Tue, 17 Jul 2001, Iljitsch van Beijnum wrote:

> Is there a known limit to the number of routes in the global routing
> table? I know bad things started to happen at about 4000 and 10000, but
> obviously those problems have been solved. Routers run just fine with 100,000
> routes at present, and unless I'm mistaken, the most common types of router
> have CPUs and memory that are well below what most of us have in our desk top
> PCs.

My PC has 768M of RAM, which is unusual.  Most have 256M or less, and I
wouldn't want multiple full BGP feeds on a router with under 256M.

> On top of that, each route takes a LOT of memory: 240 bytes for the routing 
> table and for each peer route in the BGP table in a Cisco.
> 
> If we can both increase memory and decrease the route/BGP table entry size by
> an order of magnitude, we should be able to run with a global routing table
> of 10,000,000 routes. That's about the entire IPv4 space as individual /24's.
> 
> Link speeds are high enough, and if route lookups are implemented as
> variations of binary search they are of an order log(n) so going from 10e5 to
> 10e7 should be just a 40% slowdown. The only thing that might be a problem is
> processing so many routes when BGP sessions come up.

Wow...you sure are optimistic.

> I think it's worth it to look at this, because with CIDR it is pretty much
> impossible to efficiently route traffic: many locations are hidden behind
> aggregates. Someone in Chicago has to choose between routing traffic for the
> aggregate to the west coast or the east coast, and in either case some
> traffic will have gone in the wrong direction.
> 
> Iljitsch van Beijnum
> 
> 

-- 
        "Be liberal in what you accept,
      and conservative in what you send."
--Jon Postel (1943-1998) RFC 1122, October 1989