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CEF .. Load Balancing


Would like your assistance please regarding below issue

We are having 5 TE tunnels going to same destination and we are doing load-balancing between these 5 LSPs TE tunnels.

Command "mls ip cef load-sharing full simple" is configured so that CEF will use L4 ports in its algorithm

Problem that due to CEF behavior, 2 link are v.highly utilized and the other 3 utilization are below average

What I am thinking of but not sure If this will help or not is to have 2 TE tunnels instead of 5

1 TE tunnel load balancing on 3 links ( This can be done by using static route to tail loopback poiting to the 3 links) and another TE tunnel load balancing on the other 2 links

By doing this, I think CEF would be used 2 times; first to determine which TE tunnel to use then to determine which link within the tunnel

Will this help ?

For example

interface Tunnel1

ip unnumbered Loopback0

mpls ip

tunnel destination

tunnel mode mpls traffic-eng

tunnel mpls traffic-eng autoroute announce

tunnel mpls traffic-eng path-option 1 dynamic

tunnel mpls traffic-eng fast-reroute


ip route link-1

ip route link-2

ip route link-3

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3 Replies 3

Alessio Andreoli

Hi Sherif,

i believe you should try to have a look at this link:

to better understand why and if it is really required the command "mls ip cef load-sharing full simple" you have issued. Since you are doing trafic engineering it is possibly a godd idea to state explicit paths and to load-share in this way rather than to involve only IP CEF which will have a limited visibility over the whole picture. To state the explicit path for each tunnel (whatever number is required) could be a way to address the flows as you require.

Hope this helps


Hi Alessio

Thanks for your reply

Actually in original configuration there are 5 TE tunnels configured with explicit paths to use the 5 links. Load balancing is working fine ; i.e when you do "show ip route" you will find the route known from the 5 TE tunnels

However due to CEF algorithm, most of the traffic is using only 2 links out of 5
I configured "mls ip cef load-sharing full simple" but didnt help a lot

Thats why I thought of the above solution .. but dont know If it will help or not ?




Any ideas plz

Sent from Cisco Technical Support iPad App

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