Simple TE question

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Oct 23rd, 2007
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Hello. Let's say I configure explicit TE path betwen two edge devices and it goes on suboptimal route. How should I then do a configuration so only traffic from L3 VPNs that I select goes through TE tunnel, and all other traffic goes through normal path with smallest IGP metric.

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swaroop.potdar Tue, 10/23/2007 - 12:07
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Create additional loopbacks per vrf ( in global table) on either side and manipulate the BGP nexthop to point to that new loopback, instead of regular loopback 0.


For eg:


Create loopback 1 in global for vrf1 on the egress PE. On the Ingress use a global static loopback 1 route pointing to the tunnel which terminates on this egress PE.


Manipulate the nex-hop in the MPBGP update on the ingress using import map pointing to the loopback 1 on the egress.

Or

Assign the BGP next-hop to be used for that VRF as loopback 1 in vrf config mode.


HTH-Cheers,

Swaroop

Harold Ritter Tue, 10/23/2007 - 12:24
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Swaroop,


Or even easier. If the goal is to follow the tunnel for all l3vpn traffic, just use a separate loopback interface address for the VPNv4 session and make that loopback address reachable via the tunnel interface using a static route. This way you don't need to se a separate loopback per VRF.


Regards,

djankovic Tue, 10/23/2007 - 12:27
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No, actually the goal is to tunnel traffic only for certain VRFs. Most of VRFs should still pass regular path.

Harold Ritter Tue, 10/23/2007 - 12:37
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Setting the bgp next hop under the given VRFs seems like the best option then:


ip vrf test

bgp next-hop loopback 1


Regards,


dara111983 Wed, 10/24/2007 - 10:02
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Hi Harold,


Can U suggest us any link wherein this solution has been documented???


This is a very nice flexible way of giving the service using specific TE tunnel to high priority customers requesting optimization within SP core.

swaroop.potdar Wed, 10/24/2007 - 10:22
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Here is the command reference for this toggle.

Although its not documented as a feature, so doesnt have a feature guide as far as i know.


http://www.cisco.com/en/US/products/ps6441/products_command_reference_chapter09186a00804a3736.html#wp1022044


If you want further granularity based on subnets, (for eg: only intra VPN traffic is High priority and traffic to internet is not etc.) then you may want to manually modify the next-hop rtaher than assigning the next hop per VRF using the first method which i specified in my earlier post, if you are looking for something like a Virtual leased circuit kind of service between end points then you can gurantee all traffic certain SLA using the second method 'the per VRF next-hop method'.


HTH-Cheers,

Swaroop

dara111983 Wed, 10/24/2007 - 10:46
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Swaroop's response at lightning speed :) :) :),




Thanks,

Regards,

Dara

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