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New Member

Frame Relay Backup Connection For P-T-P with EIGRP

Greetings -

I have 2 T1 Point-to-Point connections running from HQ to a Branch office. We just implemented a T1 Frame Relay backup for the Point-to-Point lines. Here is the problem:

EIGRP causes the Frame Relay line to have the same metric as the points and tries to load balance the lines. I need to have the Frame T1 stay in the background until the point-to-points fail but I cannot figure out either how to set the proper metric.

Is it possible for the Frame T1 to jump in when only 1 of the Point-to-points fail?

Thanks,

4 REPLIES
Bronze

Re: Frame Relay Backup Connection For P-T-P with EIGRP

Hi,

I suggest you decrease the bandwidth on the frame relay interface. This will increase the EIGRP metric of that line, thus sending traffic only over the ptp T1s until they go down. The interface command is simple "bandwidth x" where x is a value less than the value of the bandwidth of your T1 interfaces.

HTH

Mark

New Member

Re: Frame Relay Backup Connection For P-T-P with EIGRP

Excellent. Thanks.

Silver

Re: Frame Relay Backup Connection For P-T-P with EIGRP

While adjusting the bandwidth setting will get you the desired result, the preferred way to adjust EIGRP routing preferences is with the delay parameter. The bandwidth parameter should be set to the actual usable data rate of the link, because it is used for more than just EIGRP routing (such as calculating link loading and throttling EIGRP flooding of routes). More important, if you look up the formula used by EIGRP for routing, only the bandwidth of the slowest link in the path to the destination is considered significant in route selection.

Default delay for a serial link is 2000, so adding the statement "delay 2500" to the frame relay interface will have the desired route preference impact (verify with show ip route) and none of the potential, undesireable side effects of adjusting bandwidth.

Good luck and have fun!

Vincent C Jones

www.networkingunlimited.com

New Member

Re: Frame Relay Backup Connection For P-T-P with EIGRP

Excellent. Thank you very much.

sg

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