Ether channel & WAN Ethernet link

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Mar 9th, 2009
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I have configured Etherchannel between two Switches. These Etherchannel are buit over two WAN Ethernet links. In case of any link issue in the WAN on one of the WAN Ethernet link, since the Ethernet interface remains up, the Etherchannel is not going down and i am facing packet drops.

Did any one face a similar issue?


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Giuseppe Larosa Mon, 03/09/2009 - 00:42
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Hello Vamsi,

I would think to use LACP to be able to detect link failures.

The problem is originated from the fact that your equipment port is connected to provider port not directly.

Verify if the WAN service allows the LACP frames to flow end to end.

if so I would change the configuration in this way.

If this is not possible I would consider to use the two links as two parallel routed L3 links with a routing protocol running over them in order to detect remote end failure

Actually Metro ethernet forum provides mechanisms for detection of remote end failures with ethernet LMI that can put down a link on side A if remote side B is down. So you can check this possibility with your service provider

Hope to help


krishna.vv Mon, 03/09/2009 - 00:55
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Hi Giuseppe,

Could you please share with me the config that goes in to Cisco 2950 switch to support the LACP. Will Cisco 2950 switch able to support 2 nos of 100 Mbps wan links as etherchannel?



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