LACP EtherChannel

[AxiomConsulting]

I am trying to configure LACP between our Cisco 3750 stack and an EMC SAN.

I have 2 GigabitEthernet ports that I have put into port-channel 20, please see the below config for the 2 interfaces…

interface GigabitEthernet2/0/10

description EMC

switchport trunk encapsulation dot1q

switchport trunk native vlan 101

switchport mode trunk

speed 1000

duplex full

channel-protocol lacp

channel-group 20 mode active

!

interface GigabitEthernet2/0/12

description EMC

switchport trunk encapsulation dot1q

switchport trunk native vlan 101

switchport mode trunk

speed 1000

duplex full

channel-protocol lacp

channel-group 20 mode active

When using the above configuration the links do not come up, the port-channel interface and 2 physical interfaces show as notconnect.

However, when I switch the mode to 'on' (therfore not use a protocol) the etherchannel comes up no problem.

I have been assured that the EMC SAN is configured correctly and is able to use LACP.

I have also tried 'passive' mode with no joy!

Any help is greatly appreciated.

Steve

[glen.grant]

The switch side looks fine , without seeing the san side which is where the problem probably is it's hard speculate. If it works as "on" then maybe the san is set as on also .

[Giuseppe Larosa]

Hello Steve,

probably the EMC SAN is not sending LACP messages and the switch after a timer expiration puts the ports in a suspended state.

Check the switch log for LACP related messages with

sh log | inc LACP

By the way, this is the advantage of LACP it can detect problems with the neighbor device.

Hope to help

Giuseppe