[c-nsp] Conditional advertise-map

[Heath Jones]

Hi Gert & All,

Just a quick one.. I've been working on getting this modelled up by
using mrt dumps from routeviews.
I'm processing the tables to try and find out which AS has the most
omni-directional routing information. I mean, trying to figure out who
would get hammered the most if they were doing 'tcam aggregation'.
An AS that has a lot of non-contiguous prefixes going out of a lot of
different directions is key..

I've read in a lot of places now that if you have say 192.168.0.0/16
and then a /24 drops out, that you will end up with 255 /24's in the
table. I'm trying to understand why that is.. (classful implementation
almost?)
My thinking suggests you could have for example one each: /17 + /18 +
/19 + /20 + /21 + /22 + /23 + /24.


Any thoughts appreciated!

Heath






> Well, today I can look at my BGP sessions and say "I am receiving
> 294.712 prefixes, and so I need a TCAM that is at least that big".