2 T1'S load balancing question.

[a.mir]

Presently a remote site has a Frame T1 with a CIR of 256 and port speed of 1.544(256/1.544) through AT&T.

A second T1 is being installed which will be Point to point T1 from Timewarners.

router's involved 3660 to 7200

question is,Can i load balance/multiplex both circuits with ospf cost. since one is frame t1 and the other one is p2p T1 or would it create assymetrical routing.

so what is the best way to load balance the above situation.

Any help is appreciated.

[thisisshanky]

enable cef and adjust metrics in ospf to load balance equal cost. This will be more of per-source-destination pair load balancing. Do not use per packet load sharing in this situation, as it can cause out of order packets (especially not good for voip) since either links are through two different ISPs, latency on each link will also be different. So per-destination type LB is the best (Fast switching or CEF)

[a.mir]

Make sense, thanks for your time.

[vcjones]

PMFJI, but why would you even want to try to load balance with a 6 to 1 ratio of available bandwidth? The incremental capacity hardly seems worth the effort and the complexity introduced to try to utilize it very likely to cause problems down the road.

I suspect you would be far better served to KISS and use a simple primary/backup approach to the configuration. Only use the 256K frame link for production traffic when the primary full T1 is having problems. (But remember to constantly probe the backup link with test traffic, so you can detect when it fails and needs to be repaired).

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com