[j-nsp] full table?

[Jared Mauch]

On Sep 20, 2011, at 1:26 PM, Keegan Holley wrote:

> Is it always necessary to take in a full table?  Why or why not?  In light
> of the Saudi Telekom fiasco I'm curious what others thing.  This question is
> understandably subjective.  We have datacenters with no more than three
> upstreams.  We would obviously have to have a few copies of the table for
> customers that want to receive it from us, but I'm curious if it is still
> necessary to have a full table advertised from every peering.  Several ISP's
> will allow you to filter everything longer than say /20 and then receive a
> default.  Just curious what others think and if anyone is doing this.

Generally what I've recommended for people with older routers for years is
to just take the 'on-net' prefixes from your upstreams.  This allows you to
send traffic most optimally to these networks without the need to have a
'full' table.  Anyone that isn't a customer of your upstream is harder for
them to solve issues with typically as well.  (then just point default at
your lowest cost transit).

This method can reduce the memory footprint better than picking some arbitrary
netmask to filter with (e.g.: /20, /24, etc).

It may not work as well with some networks: Level3 has about 150k on-net
prefixes last time I checked.

- Jared