MPLS Question

[Mavrick25]

Hello Everyone,

Is there a way to implement policy based routing in mpls..

Basically, I only want the Loopback's advertised within the core not the point-2-point links..

Is this possible??

I don't think so, just a simple question..

PR

[Konstantin Dunaev]

Hello,

just to be sure, are you talking about MPLS VPN or just MPLS as forwarding process for  other applications(TE, L2 tunnel and so on)?

For MPLS VPN you don't need to advertise all linknets, it's enough if you advertise into MPLS only loopbacks, then you establish BGP  session between those loopbacks and the traffic will be label-switched if all loopbacks gets correct labels. In this case you don't need  any art of policy-routing.

For other MPLS applications I can't say is it's possible or necessary.

regards,

Konstantin

[Mavrick25]

Hey,

Just MPLS... with no VRF implementation..

[Atif Awan]

Mavrick25 wrote:
Hello Everyone,
Is there a way to implement policy based routing in mpls..

Basically, I only want the Loopback's advertised within the core not the point-2-point links..
Is this possible??
I don't think so, just a simple question..
PR

The question is a bit vague for me. PBR itself is different than controlling routing advertisements. If you actually want to limit prefix advertisment to only loopbacks then take a look at prefix suppression feature for OSPF (http://www.cisco.com/en/US/docs/ios/12_4t/12_4t15/ht_osmch.html).

Atif

[Mavrick25]

Basically, when you perfrom a "show ip route" on a core MPLS router..

You should see only the IGP routes.. want to limit this to only the loopbacks

[Atif Awan]

Mavrick25 wrote:
Basically, when you perfrom a "show ip route" on a core MPLS router..
You should see only the IGP routes.. want to limit this to only the loopbacks

Then look at the prefix suppression feature that I listed in my previous post.

Atif

[Mavrick25]

Thanks, I'll take a look.. but were not running OSPF.. but

ISIS

[Atif Awan]

Mavrick25 wrote:
Thanks, I'll take a look.. but were not running OSPF.. but
ISIS

If it is IOS take a look at the 'advertise-passive-only' command:

http://www.cisco.com/en/US/docs/ios/iproute_isis/command/reference/irs_is1.html#wp1010942

For IOS-XR I believe you can configure the respective interfaces as suppressed.

Atif

[Konstantin Dunaev · Accepted solution]

Hello,

it might be that I'm mistaken but it has nothing to do with MPLS isn't?

Mavrick25 wrote:
Basically, when you perfrom a "show ip route" on a core MPLS router..
You should see only the IGP routes.. want to limit this to only the loopbacks

what  you'd like to achive is just to reduce the routing table on core  routers , so that they have only PE's loopbacks IP's in it.

check this document:

http://www.cisco.com/en/US/prod/collateral/iosswrel/ps6537/ps6554/ps6599/ps6629/prod_presentation0900aecd80310f6d.pdf

or (more recent version)

http://files.netcore.be/Cisco%20Networkers%202009%20-%20All%20Sessions/Breakouts/BRKIPM/BRKIPM-2310/BRKIPM-2310.pdf

it's about OSPF, but I think one can easly migrate the solution to ISIS.

The  main  idea is the IGP routing table sees only Loopback IP, and all  "external" routing information will be contained in BGP and with help  mext-hop-self the traffic will be forwarded between the hops.