BGP and aggregation

Sun May 12 19:58:54 UTC 2002

Don't forget that if both sites use the same as even if the connection 
link drops they will not be able to see each  other over the upstream 
provider as routers won't take the srutes from the same as.  If this 
isn't a problem don't worry about it.  If you wish to preserve 
connectivity between cities you should have a back-up link or use 
different as's or gre tunnels:).

On Sat, 11 May 2002, Ralph Doncaster 
wrote:

> 
> I have transit in 2 cities.  I have a circuit connecting the 2 cities as
> well.  So far I've been using non-contiguous IPs, so there's been no
> opportunity for aggregation.  Having just received my /20 from ARIN, I'm
> trying to plan my network.  Lets say I split the /20 into 2 /21's, one for
> each city.  I'd like to announce the aggregate /20 instead of 2 /21's, as
> long as the circuit connecting the 2 cities is working.  If the circuit
> goes down I want each city to announce the local /21.  Is this
> possible? (using either a Cisco router or Zebra)
> 
> Ralph Doncaster
> principal, IStop.com     
> div. of Doncaster Consulting Inc.
> 