[c-nsp] design ? - two POPs, same AS or different?

[Roldan, Brad]

Hi Matthew,

It is possible to have two POPs with the same ASN, although purists will
argue that this violates some fundamental unspoken design rule. If you
plan to also advertise the aggregate /20, you'll need to be careful
about how you inject the route in your local tables. The Internet at
large should be able to find your /22s in Europe and San Jose with no
problems. Traffic at your POPs advertising the /20 will likely go to
null0 if you just use the "aggregate-address" command. Without seeing
your actual configs, I'm just guessing.

At the location(s) where you would want to advertise the /20, one
possible solution would be something like...

router bgp <your ASN>
 aggregate-address 10.10.0.0 255.255.240.0
!
! Create a covering route, or a everything will go to Null0 
ip route 10.10.0.0 255.255.240.0 <eBGP neighbor next hop IP>
!


The solution has some drawbacks, but gets the job done.

Regards,

Brad
-- 
Covad Communications 
2510 Zanker Road 
San Jose, CA 95131 


-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of matthew zeier
Sent: Thursday, August 17, 2006 10:42 PM
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] design ? - two POPs, same AS or different?



This is a design question and I'm not sure the "best" way to solve this
- 
looking for suggestions.

I currently have a site in San Jose announcing a /22 out of my larger
/20 
behind a particular ASN.  In a couple months I'll be opening a second
site 
somewhere in Europe and announcing another /22.

I won't have any physical connection between each site but will need
each site 
to talk to each other.

Would I be better off getting a second ASN, putting up GRE tunnels and
peering 
or use something like allowas-in?

And to add to the complexity, at some point in the future I'll be
anycast'ing 
a portion of that /20 out of each site.

Thanks.

- mz
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