[nsp] relevance of ibgp in private mobile transit backbones?

[padma krishnaswamy]

Sorry about the HTML. It's off now. and thanks much for the input- most 
appreciated
regards

Padma


>From: Ryan O'Connell To: padma krishnaswamy , cisco-nsp@puck.nether.net 
>Subject: Re: [nsp] relevance of ibgp in private mobile transit backbones? 
>Date: Sun, 8 Sep 2002 20:22:35 +0100 (GMT Daylight Time)
>
>Please turn off HTML mail when posting to the list. It makes your message 
>very hard to read.
>
>On Sun, 08 Sep 2002 18:19:18 +0000 padma krishnaswamy wrote: >
a question that i hope is not too off topic for this list.
> >
The convention (to transmit BGP  acquired routes cross
> > network) is to use IBGP in transit nets. IBGP is chosen to > spare the 
>IGP-related complications caused by needing to carry large > numbers of BGP 
>routes if an IGP were used to do so , and not IBGP. >
If the scenario is one where
> >
1) the number of BGP routes at each border gateway may be much
> > lower than for the commercial internet
> >
2)the transit network consists of relatively mobile nodes -thus
> > making  tcp meshes rather tricky to maintain-
> >

> >
what scales (total no of routes across all border routers) is it
> > worth considering an IGP such as OSPF to carry BGP routes across the > 
>transit net?
>
>I assume by "carry BGP routes across the transit net" you are talking about 
>non-border routers only and you will still run iBGP between AS border 
>routers? I don't think it would ever be worth using an IGP rather than BGP 
>between border routers these days.
>
>How many routes are you talking about here? I woud not imagine any well 
>designed private network should have more than a couple of thousand routes 
>in it's BGP routing table - which any competant IGP should be able to 
>handle as external routes given enough memory. I do not think you would 
>have a problem unless you have a particularly messy IP allocation strategy 
>and can't aggregate much.
>
>--
>Ryan O'Connell Mail: ryan@complicity.co.uk CV: 
>http://www.complicity.co.uk/ryancv.pdf CCIE #8174

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