BGP and aggregation

Sat May 11 21:34:39 UTC 2002

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.