[c-nsp] best way to announce ibgp routes

[Bruce Pinsky]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

matthew zeier wrote:
> I'm tossing around two ideas to announce my ibgp routes and I'm not sure on 
> the pro/cons of either.  Look for recommendations.
> 
> I have several "border" routers that connect to the Internet which are in turn 
> connected to several "core" routers.  Customers hang off the core.  All 
> routers run bgp and ospf.
> 
> A. Do I initiate ibgp routes from the core with nailed up statics and 
> appropriate network statements?
> 
> B. Do I initiate ibgp routes on the borders with appropriate network 
> statements and depend on IGP to get me the routes (with sync on)?
> 
> 

Regardless of whether you initiate the routes at the borders or the cores,
keep your customer assigned addresses in BGP and your infrastructure routes
in your IGP.  Don't mix. The IGP's purpose is to provide the routing
infrastructure to support the BGP sessions and infrastructure management.
Nothing more.

As Justin indicated, you could announce the routes from the borders and
allow the cores to simply be route reflectors.  On the other hand,
initiating the routes from the cores (where the customers are located) may
be beneficial if you wish to have those routes withdrawn if the
interface(s) to the customer segments/sites goes down.

If you initiate at the borders, you should consider using conditional route
advertisement to prevent external advertisements in the event of network
segmentation.


- --
=========
bep

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.0 (MingW32)

iD8DBQFDAirDE1XcgMgrtyYRAvPyAKDybVWFgOrk8bWGV8zoAlH4N/LUAwCfQLAO
mh0ahKjAnp8DnlBlDsjRjZc=
=SdnV
-----END PGP SIGNATURE-----