Actually I ran this way for a while as a primary. I had three sites attached via cogent entirely all announcing a /19 and the internally a /21 each and a couple /21's out of the primary location. In the main location was a 7507 and in the two other pops 6509's. We set ospf internally, set up bgp for the announcements at each site and used the no-export tag for the more specifics. Then gre tunnels:) for the internal. It worked and I pushed probably 45 to 50mb over the internal loops or gre tunnels. Not ideal but it worked. On Sun, 12 May 2002, Stephen J. Wilcox wrote:
Interesting point there Scott.. we were discussing just that at a recent IXP meeting I was at. Theres a number of different ways (well hacks) in which you can keep connectivity between two halves of an AS network in the event of a split.
Is anyone out there actually doing something either this or similar to keep two halves connected in the event of a split.. and have you actually run successfully on your backup and maintained a reasonable throughput (say 30 or 40Mbs) ? I'd be interested if anyone has a proven technique as I want to implement something myself and dont really want to test it by pulling the plug on some backbone links and waiting to see what happens!
Steve
On Sun, 12 May 2002, Scott Granados wrote:
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.