EIGRP Load-Balancing

[G Money]

Greetings,

I have several remote offices. Each remote office router has 2 links coming back to the main office: dual T1 ATM IMAs connecting to a 6509 and single T1s connecting to a 7507. All traffic goes across the ATM links, even when they're saturated, and T1s are left unused.

Is it possible to load-balance traffic across these two unequal cost paths without using policy routing? The variance command doesn't seem to work.

Thanks,

George

[mehrdad]

Hi,

the variance should be worked, please check your variance value.

the T1 connection should be feasible successor, do you see it at the result of this command :"show ip eigrp topology" ?

Regards,

Mehrdad

[G Money]

The routes do show up in the EIGRP topology table and the show up in the routing table, but all traffic still goes across the ATM links. I think the variance command doesn't work because the 2 links connect to 2 different routers at the main office.

[mehrdad]

no i don't think so,it should be worked if the two links connect to two different routers.

pls check this out "traffic-share balanced" under your EIGRP configuration.

for instance :

router eigrp x

network x.x.x.x

variance x

traffic-share balanced

[Harold Ritter]

The variance is only effective if the additional paths are flagged as feasible successors. Otherwise it won't work.

Hope this helps,

[G Money]

If the additional paths are put in the routing table doesn't that mean that they're flagged as feasible successors? Thanks.

[Harold Ritter]

Correct. Sorry, I had missed that part. If both paths are installed in the RIB and the traffic is only using one path then the issue might be that the traffic is generated by one or a few flows (src and dst IP addresses), in which case CEF might send all traffic via the same path. CEF per prefix loadbalancing (which is really per flow loadbalancing) is on by default.

Hope this helps,

[G Money]

No worries. Can you think of any other ways to try to troubleshoot this outside of policy routing?

[G Money]

It didn't seem to help. Thanks.

[Richard Burts]

George

Perhaps it would help if we could have some specifics to look at. Can you post relevant parts of the router config, the relevant output of show ip route, and the output of a traceroute to one of the remote destinations?

HTH

Rick