/24s run amuck

Tue Jan 13 20:48:30 UTC 2004

On Jan 13, 2004, at 2:19 PM, Steve Francis wrote:

> I'll take some education - given two POP's, different upstream ISPs at 
> each POP, and a desire to have traffic for specific networks (/24) 
> enter a specific POP, can that be done without de-aggregation?
> We are not doing this ourselves - we're not yet big enough to have our 
> own aggregate blocks, but if we did, we could not just announce a /20 
> at each POP, and transit the traffic back to the appropriate 
> datacenter ourselves. We're an ASP, and do not have real links between 
> POP's, only VPN's.
>
> If we used consistent upstreams at each POP, we could do it by 
> announcing specific /24's with no-export communities, but a consistent 
> set of ISPs are not available at each of the colo's we are in.
>
> Is there some other trick I'm missing?

If you can't take the traffic from Site A to Site B, why are you 
announcing the /24s to the world?  Why not just use a /24 from the 
upstream in each location and not force everyone else on the Internet 
to see your /24 which only has one path?

Your /24 will be covered by the larger CIDR from the upstream in each 
location.  That's more stable anyway, announcing the /24 might get you 
dampened or something, and then you'd lose all connectivity.

-- 
TTFN,
patrick