MPLS Query

Unanswered Question
Aug 15th, 2010

Hi,

I was doing some basic MPLS VPN guided by the below document, but I couldn't get it to work because i was using a 2691 and its interfaces do not have tag-switching or ip mpls command available on it.  Nevertheless, i finally just enabled ip vrf forwarding siteA on all the interfaces including the L0 and got it to work.  Just wanted to know if the solution is acceptable.  Thanks.

http://www.cisco.com/en/US/tech/tk436/tk428/technologies_configuration_example09186a00800a6c11.shtml

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u1kumar2002 Mon, 08/16/2010 - 03:05

Hi,

   Instead of tag-switching use mpls ip (LDP). enable mpls ip globally and apply wherever you are using tag switching. It will work.

If you want reference of ready lab have a look on this page. Refer the config for VRF VPN_B.

http://startnetworks.blogspot.com/2010/07/mpls-l3-vpnsham-link-as-override.html

Hope this information will help you...

Uttam

http://startnetworks.blogspot.com/

Giuseppe Larosa Mon, 08/16/2010 - 04:13

Hello Marcus,

you have implemented VRF lite:

interfaces are put in different VRFs but no MPLS backbone interface exist.

the limit is that for each VRF/VPN you need to build and end to end topology as you cannot rely on MPLS for forwarding

if you cannot enable mpls ip on global config the problem is related to the IOS image running on your device.

you need to :

a) enable cef globally

ip cef

b) enable mpls globally

mpls ip

c) to enable mpls on backbone facing interfaces using

int type x/y

mpls ip

if you cannot do this it is a problem of IOS version

Hope to help

Giuseppe

vdineshkumar83 Mon, 08/16/2010 - 22:28

Hi Marcus,

          Can you give us hint on your setup. If you have similar setup as given in your refference URL then you should be running Mp-BGP for VPN routes exchange and IGP for Edge & Core reachability. And you should have enabled tag-switching ip in your backbone, If this is the case, then it shoudn't work (Edge PE- IP's label would be seen as  untagged in BB (since interface connecting to edge PE is not mpls enabled) so it will try to lookup the VPN prefix info in BB itself. I can get clear picture if you could provide the n/w diagram

Regards,

V Dinesh Kumar

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