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port-channel issue over ciena DWDM

Hi all, 


I'm currently working on an issue encountered on a DC. 

We currently use 2 3750 stacks (1 in each DC), connected with a Po. 

We use dark fiber between each DC, so we have a Ciena DWDM transponder on each side. 

The problem is that, if we have an issue on the inter-DC fiber, the Ciena interface on the 3750 side is still up. Using LACP on the Po, the issue can be detected in about 3 X 30 sec = 90 sec. 

Before the issue is detected by LACP, the impacted port-channel interface is still used by the Po, which can cause big issues. 

I thought use an EEM applet in order to monitor the CDP neighbor on each interface, and exclude the interface from the Po till the CDP neighbor is down, but the CDP timers are even bigger (180 sec hold-time). 

Is there any way to address this problem, other than UDLD ? 


In our others DC, we have two NX7K on each side, and we are able to use LACP with fast-rate, but this is not available on 3750... 


Thank you very much ! 


the best way to use pair of

the best way to use pair of transponders on each side in protection group.

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