From: Joe Rinehart (jjrinehart@hotmail.com)
Date: Fri Sep 09 2005 - 20:06:45 GMT-3
Anyone feel free to jump in if I am way off base here...
It's pretty much just a function of how the routing is set up...I created a
mini-MPLS network on my lab rack and really was surprised to see how the
mechanics all work, especially as I tried to mimic how we have it set up at
AT&T. The feature you are referring to is sometimes called a route-free
core. The label switched core itself doesn't have any knowledge of edge (or
MPLS VPN) routes at all, they are clueless of anything outside the backbone
itself. Usually an IGP like OSPF or ISIS is run between the P nodes in the
core and includes the PE devices too. I had one router get all buggy
because of short memory so I verified just using static routing across the
simulated backbone and that worked too. The core just uses IGP and internal
routes and does the label switching from PE to PE.
The magic is at the PE, it's pretty much doing all the heavy lifting. The
PE runs BGP at the edge only, peering with the CE (using eBGP) and other
PE's (using iBGP), and it's also responsible for creating the MPLS VPN's
using Route Distinguishers and Multiprotocol BGP. The core doesnt know,
doesnt care and doesnt play with BGP or the VPN's, it just pushes traffic...
The same would apply to Internet routes, as the BGP on the edge/PE routers
would know all of it, advertise routes, and such, but once passed to the
core P routers it would be label switched....
It really is cool fascinating stuff.....
Joe Rinehart
CCIE #14256, CCNP, CCDP
Data Network Consultant
AT&T Pacific Northwest Enterprise Markets
----- Original Message -----
From: "Richard Dumoulin" <Richard.Dumoulin@vanco.fr>
To: <ccielab@groupstudy.com>
Sent: Friday, September 09, 2005 2:03 PM
Subject: Cisco MPLS
> There is a feature in MPLS that I find powerful and it is the possibility
of
> building an Internet backbone with 160000 routes present only in the PEs
> routing table. I was wondering if this was only a Cisco feature or do the
Ps
> of other vendors also support this like Juniper for example?
>
> Thx
>
> -- Richard
>
>
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