routing between provider edge and CPE routers

Wed Jan 29 19:53:23 UTC 2003

 My recommendation would be for you to: 

   o redistribute directly connected interfaces via a strict
     filter into BGP and use iBGP to carry it around the local
     AS 

    or 

   o use passive interfaces in IGPs to do the same

 Avoid having to run a topology computation everytime a T1/56k 
 links drops. I prefer the first option to the second based on 
 experience UUNET / Global Crossing has w/ option #1. 

	- Serge

Thus spake Mike Bernico (mbernico at illinois.net):

> 
> 
> Hi,
> 
> I apologize if this has been asked before.  I work for an ISP that
> started very small (hundreds of T1 and 56k customers) and has grown very
> large in the last few years (thousands of T1 customers, as well as DS3
> customers and OC3 customers).  
> 
> We currently use an IGP to route between our distribution routers and
> the CPE routers we manage.  This has historically worked very well. We
> have recently begun running into scalability issues however.  We have
> some distribution routers that have over 1000 T1 interfaces on them.
> This is causing some problems with stability in that edge IGP.  Does any
> other service provider use an IGP all the way to the customer for non
> BGP customers or are we the only one?  I have a feeling we maybe are.  
> 
> If you do use an IGP, have you had any of the scalability issues we have
> had?  How did you fix them?
> 
> If you use statics/BGP to CPE routers have you had any issues doing
> that?  In particular I'm wondering about the thousands of lines of
> configuration used to make static routes work.  
> 
> 
> Thanks in advance for your advice.
> 
> Mike Bernico