too many routes

John A. Tamplin jat at
Wed Sep 10 17:52:20 UTC 1997

On Wed, 10 Sep 1997, Joseph T. Klein wrote:

> Having hopelessly screwed up my facts ... I was trying to make a point here.
> So the router was worse than I thought. Retaing policies that exclude
> new players because of AGS+'s inability to handle large routing flaps
> just does not cut it.
> Sprint imposed this at a time when 7000s with 64M of memory where available.
> Will /19 remain policy when the majors are running with Cisco 12000 and GRFs?
> The CPU issue has more to do with changes in the routing table rather than
> the size. Aggrigation is good because if properly implemented it reduces
> router flaps. If aggregation is the goal then mechanisms should be developed
> for exchanging CIDR blocks so the address space can be re-packed.
> The /19 policy is archaic. It creates an obstacles and only partly resolves
> the problem. Fixing holes in CIDR blocks, exchanging fragmented blocks for contiguous
> blocks, and cleaning up "The Swamp" can do more for the stability and size of
> the routing table.
> BTW - If you use a route server to do the dampening and calculation of peer
> routes you can even make a wimpy CPUed 7000 handle backbone traffic.

When the class A's are chopped up into CIDR blocks, the number of routes
in the backbone routing tables will dramatically increase, even if all of
them are /19 or larger.  Saying that instead of filtering routes Sprint 
should have just waited for everyone to clean up the routes as you suggest
seems silly -- they did what they had to do to keep their network 
operational.  They can't afford to rely on other people cleaning up their 

I am not sure what policies you think should be there that aren't -- we are
renumbering existing blocks into our own /18, and will be returning those
blocks to our upstream providers.  They get the benefit of having their 
address space back, our aggregates drop in half, and we get the benefit of
the full use of our multiple connections.  I don't see a problem with that,
and there was no difficulty getting the address space telling them what
we were going to do.

John Tamplin					Traveller Information Services
jat at Traveller.COM				2104 West Ferry Way
205/883-4233x7007				Huntsville, AL 35801

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