[c-nsp] VRRP for eBGP

[Joseph Jackson]

> On Wed, Oct 04, 2006 at 04:41:32PM +0700, Frank Cisco wrote:
> > We have two BGP internet router gateway installed. If one customer 
> > connect to both BGP router, we worry the requirement for memory at 
> > customer site will be increased double. We are thinking to use VRRP 
> > configured on our internet router, and ask customer to use 
> virtual IP 
> > as neighbor IP address. Our customer normally use eBGP 
> multihop to us.
> > Anybody have experience with it and found no issue on it ?
> 
> I have no experience with that - but doing the 
> gedanken-experiment, I have a question - if you do it that 
> way, if one router fails or otherwise hands off its VRRP 
> address to the other router, won't the customer's BGP session 
> go down and have to re-connect with the new router?  
> Depending on the customer's network, they may be off the air 
> during the changeover.

Yes they would most likely be off the air durning that time.  But if
that is a concern for them they need to get a bigger box to handle the
routing table for two bgp peers.  In tests that I have done with this
same type of setup (using HSRP tho) you will see a downtime of 1 minute
and 30 seconds until you can begin to access sites on the internet.
Though that was when HSRP was running between too routers connected to 2
differnet ISPs.  In this setup it might be only a few seconds. 


Joseph