Posted on January 5, 2021 3:34 pm
 |  Asked by Maurice Townsend
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I have 2 arista 7060cx using a breakout cable going to 1 7280sr2k. I’m using 8 ports from each 7060 breakout to the 7280. The ports will not come up. I have configured 1st lane on 7060s with speed forced speed 100gfull. On the 7280, I have each lane configured at speed forced 25gb. The port channel will not come up. I am using port 33-48 on 7280sr2k which are 25 gig ports.  I have attached a pic of the qsfp.

Posted by Kenneth Finnegan
Answered on January 5, 2021 7:40 pm

It sounds like the issue is that you're trying to run it as a 100G interface on one side, and a 4x25G port channel on the other side, which are two different things.

You'll want to configure all four lanes (eth1/1-eth1/4) of the 7060 as 25G interfaces, then configure all four of them as members of a port-channel to match the config on the 7280 side. Then the link should come up as a 4x25G port channel.

Posted by Naveen Chandra
Answered on January 7, 2021 3:11 am

Hi Maurice,

Thank you for writing to the forum. Just wanted to add on how it works. Both side interfaces negotiate on link speed before the link comes up. If the negotiation is successful then only the link comes up. And for a successful negotiation, both side link speed should be the same.

So as Kenneth said, could you please try by configuring the same speed at both the ends of link and check?



Posted by Howard Miller
Answered on January 20, 2021 4:29 am

Newly Added Interface Does Not Come Online In a Port Channel, page 7-4 If one link fails, traffic previously carried on this link is switched to the Ensure that all interfaces in the port-channel have the same destination device for LACP.






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