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Tunnel interface selection

Hi,

Apologies in advance but im new to MPLS, But is possible to have more than one pysical interface in a tunnel and is it possible load balance accross the physical links ?

2 REPLIES
Cisco Employee

Re: Tunnel interface selection

I assume you are referring to a TE Tunnel interface?

So ... A TE tunnel can use explicit path selection (you define the hop by hop path that it takes) or dynamic selection.  While you can set priority for multiple explicit paths to be configured, I do not believe you can set one tunnel to load balance over multiple links ... sort of goes against the point of having a TE Tunnel.  Normal use of  TE Tunnel is to set a defined path, with reserved bandwidth given to TE Tunnel traffic over the links in that path.

You could, however, load balance across multiple TE tunnels, which is a more common implementation.

Re: Tunnel interface selection

Hi Stephen,

If you want two port to be bundled in TE tunnel for load sharing which is not possible. But yes you include one port in
tunnel and leave another port in IGP then you can load share between them with below rules (But both should have equal cost to destination)

1-You will never load share between an IGP route and a TE route for the tunnel tail.
2-You might load share between an IGP route and a TE route for nodes behind the tunnel tail.

Algorithm by default include both tunnel path and igp path in path list.

If ou want to load share between two TE tunnel then.....

Both kind of load-sharing is possible with TE tunnel i.e equal cost load sharing and
unequal cost load sharing.

If you do not set any load share value it pick from bandwidth command. (like if bw is 20,20,40 meg then load sharing
will be in ratio of 1:1:2)

command: "tunnel mpls traffic-eng load-share --value--"

you can verify the load share with below command

"show ip cef exact-route source-ip destination-ip"

or

"sh ip cef destination-ip internal"

please remember if you use same source and destination then it will show you same tunnel for all traffic. Please try changing source and you will see different tunnel used.

Hope this helps

Regards
Mahesh

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