[c-nsp] [**** SPAM **** ] - Re: Filtering /24s - Found word(s) anal anal in the Text body

[Scott Granados]

You could filter on 24's something like this

Make a prefix list
Ip prefix not-to-specific seq 5 permit 0.0.0.0/0 le 24 (or 20 or 19)


Then apply an inbound route map
Route-map transit-provider-in permit 10
Match ip address prefix not-to-specific
Set (community tag or what ever else you need internally)


Anything longer than your prefix list allows (24 in my case) gets
filtered.
-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Greg Boehnlein
Sent: Wednesday, March 15, 2006 4:43 PM
To: cisco-nsp at puck.nether.net
Subject: [**** SPAM **** ] - Re: [c-nsp] Filtering /24s - Found word(s)
anal anal in the Text body

On Wed, 15 Mar 2006, Greg Boehnlein wrote:

> Hello,
> 	We are looking at some strategies to reduce the load on our core

> routers by filtering all routes that are /24 or smaller. The number of
/24 
> routes that have propogated in the recent couple of years seems
enormous 
> to me, and we are starting to hit the limits of the RSP-2 cards in our

> 7500s. Short of chucking the Cisco gear and replacing w/ something
that 
> can handle a larger table, it seems reasonable to me that we could 
> probably reduce the total number of routes significantly if we just 
> dropped all the /24s on the floor and let our upstreams handle the
routing 
> for us.
> 
> Am I nuts?

Since I am answering myself, let's just assume that I am nuts.. ;)

However, I'm actively looking at a couple of different strategies for 
doing this.. The anal retentive performance nut in me says that I should

make sure that whatever I do should be done at the highest level in the 
filtering process to insure that I minimize impact on the router. That 
being said, I'm reading through a variety of the filtering options 
available to me... does anyone have any suggestions on how this can be 
done?

Also, I thought I might find this information on the cidr report, but I 
couldn't find it there. Is there a graph that shows you the distribution

(in percentage) of CIDR announcements? I.E. I'm looking to find out what

percentage of announcements are at what levels so I can determine what
the 
potential memory savings could be on our Cores..

Thanks in advance..

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