EtherChannel on C3750G

[johnlloyd_13]

hi all,

i was asked to set auto/auto on gig ports for an etherchannel and i got the below syslog.

Nov 16 12:46:30.218 SGT: %EC-5-CANNOT_BUNDLE2: Gi2/0/10 is not compatible with Gi3/0/10 and will be suspended (speed of Gi2/0/10 is 100M, Gi3/0/10 is 1000M)

port g2/0/10 is now "suspended"  due to speed mismatch. i would like to know if server NIC (controlled by another admin) on port g2/0/10 needs to be configured to 1000 mbps to solve this issue?

is auto/auto locally configured on both g2/0/10 and g3/0/10 will work for etherchannel port or is it dependent on the remote device (server)?

3750#sh etherchannel summ | i 10

10     Po10(SU)        LACP      Gi2/0/10(s) Gi3/0/10(P)

3750#sh int g2/0/10 status

Port      Name               Status       Vlan       Duplex  Speed Type

Gi2/0/10  Server-NIC1       suspended    177        a-full  a-100 10/100/1000BaseTX

3750#sh int g3/0/10 status        

Port      Name               Status       Vlan       Duplex  Speed Type

Gi3/0/10  Server-NIC2       connected    177        a-full a-1000 10/100/1000BaseTX

[Beetlejuice01 · Accepted solution]

Yes, the ports must be twin. Same speed same configuration, and same media. The 2/0/10 must be a-full a-1000. Don't try to force interface it will work but it can create a lot of performance problem. Try to ask to the other admin to configure interface at 1000 and enable NIC Timing of course.

[flokki123 · Accepted solution]

hi john,

it is actually dependend on the other side as well, as if the switch side is configured as auto and the server side as e.g. 1000mbit full, it is still possible that a duplex missmatch will occur.

auto on both sides is the best solution i would say and auto is also the recommended best practice from cisco as far as i know.

otherwise configure it like fabio mentioned.

regards,

florian

[johnlloyd_13]

Thanks for your inputs!

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