Re: BGP and aggregation

["Stephen J. Wilcox" <steve () opaltelecom co uk>]

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.