Re: MPLS Backbone over Frame-Relay Issues

HI Joe Astorino

I understood your lab design.

I think MP-iBGP behave correctly, R2 should see the R4 and R6 as the
next-hop for the routes learned from VPN-A and B

I assume the LDP work perfectly

How is the fram-rely setup, are you using the point-to-point connection
between the hub and spokes. Is the ospf configured as point-to-point
network type?

What is the output show mpls forwarding-table at R2, R4 and R6

At R2 you should see the outgoing labels for R4 and R6 loopback IP, same
thing for R4 and R6 you should see the labels for other PEs

Do debug mpls packets at R6, and then try to ping from one site to other
remote site. you should see the MPLS packet pass through R6

If you can send us the config of all router, that would be great

Regards

Pandi

On Mon, Jun 15, 2009 at 3:54 PM, Joe Astorino <jastorino_at_ipexpert.com>wrote:

> Hey guys, I am hoping somebody can help me understand a bit of an issue I
> am
> having. I am actually just starting out learning MPLS and MPLS VPN
> technology, and set out to give it a go tonight in the lab. I have 4
> routers connected in a frame-relay hub/spoke topology: R2, R4, R5, R6 with
> R6 being the hub. Each spoke router only has a PVC to the hub router, R6,
> so any spoke to spoke connectivity will have to pass through R6. For my
> MPLS VPN experiment, I wanted the R2,R4,R5 frame routers to be PEs.
> Additionally, so that I could fully experiment with a MPLS "cloud" I needed
> a P router...since R6 is my frame-relay hub, and all traffic through the
> MPLS cloud has to go through it, I figured R6 would be a fine P router.
>
> Off of R2 I have 2 VPNs, one on each fastethernet interface. I call them
> VPNA and VPNB (how creative hehe). Off of R4, I have a VPNA CE router.
> Off
> of R5, I have a VPNB CE Router. The CE/PE IGP is RIPv2. Inside of my
> frame-relay cloud, I am running OSPF.
>
> Next, I setup MP-BGP between the PE routers, using R2 as a RR. I did the
> mutual redistribution into MP-BGP / RIP and everything appeared to be
> fine...I could see the proper routes in on all my VPN routers! Awesome.
>
> The problem came when I actually tried to ping...<sigh>. After a long
> night
> of troubleshooting I actually did find the issue, but don't know how to
> solve it yet. If I try to ping from a VPNA CE router across the MPLS to
> reach one on the other side, it fails. The reason it fails is this from
> what I can tell: R2/R5/R6 are all learning the vpnv4 routes through MP-BGP
> fine, but they see the next hop as the other end's loopback. For example
> R2 (2.2.2.2) peers with R4 (4.4.4.4) and R5 (5.5.5.5) ... so when I attempt
> to ping a vpnv4 route that lives in VPNA off of R4 on the other side, R2
> sees the next hop as 4.4.4.4 ...it then recursively looks up 4.4.4.4 in
> it's
> routing table and finds a next hop of 150.100.100.4 (R4's frame interface)
> and NO LABEL IS FOUND. My LDP session is up between R6 and all my spokes.
> My loopbacks are in OSPF...it seems when OSPF advertises from one spoke to
> the hub, and the hub (also the DR) advertises that route down to the other
> spokes, the next hop does not change....so instead of my next hop in the
> recursive lookup being the frame hub , it is the spoke. The entire frame
> cloud uses only physical interfaces, and everything in the same subnet.
>
> I hope I explained that well enough for somebody to help out. Has anybody
> else out there ran into this? Is it possible to have your frame-relay HUB
> be a P router and not run BGP at ALL like this?
>
>
>
> Regards,
>
> Joe Astorino
> CCIE #24347 (R&S)
> Sr. Support Engineer - IPexpert, Inc.
> URL: http://www.IPexpert.com
>
>
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Received on Mon Jun 15 2009 - 16:47:06 ART