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Article description: This article explains how to resolve LACP port ungrouping due to mismatching LACPDU timers.

When creating a LACP Link Aggregation, all Force10 switches (with the exception of the I/O Aggregator) have two transmit timer values. This value determines how often the ports send LACPDUs. The default is one LACPDU sent every 1 second. You can also configure it to send one every 30 seconds with the lacp long-timeout command. Long-timeout is best practice and recommended for the Force10 switches.

When the LACPDU transmit timer values mismatch, this can cause intermittent ungrouping of ports, thus causing connection issues. The following command and output helps determine how many LACPDUs being sent and received. This example uses LACP 10.

FTOS#clear lacp 10 counters

FTOS#show lacp 10 counters

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LACP PDU Marker PDU Unknown Illegal

Port Xmit Recv Xmit Recv Pkts Rx Pkts Rx

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Gi 0/1 4560 152 0 0 0 0

Gi 0/3 4560 152 0 0 0 0

As you can see, Xmit represents LACP PDUs sent and Recv is received from the partner device. In this scenario, the Force10 switch is sending LACP PDUs faster than the connecting device. To resolve this, we run the following command to send LACP PDUs every 30 seconds instead.

FTOS#config

FTOS(conf)#interface po 10

FTOS(conf-if-po-10)#lacp long-timeout

FTOS(conf-if-po-10)#end

FTOS#wr

Now verify the timers again.

FTOS#clear lacp 10 counters

FTOS#show lacp 10 counters

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LACP PDU Marker PDU Unknown Illegal

Port Xmit Recv Xmit Recv Pkts Rx Pkts Rx

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Gi 0/1 10 11 0 0 0 0

Gi 0/3 10 11 0 0 0 0

The two switches are sending and receiving LACP PDUs at the same speed. Keep in mind that lacp long-timeout is best practice in Force10 and is recommended.