Viewing LACP Counters

Use the show lacp counters command to display statistical information about LACP ports.

Note on the Marker Protocol. Data traffic can be dynamically redistributed in port channels. This may occur when a link is added or removed, or there is a change in load-balancing. Traffic that is redistributed in the middle of a traffic flow could potentially cause mis-ordered data packets.

LACP uses the marker protocol to prevent data packets from being duplicated or reordered due to redistribution. Marker PDUs are sent on each port-channel link. The remote system responds to the marker PDU by sending a marker responder when it has received all the frames received on this link prior to the marker PDU. When the marker responders are received by the local system on all member links of the port channel, the local system can redistribute the packets in the traffic flow correctly.

For the switches covered in this guide, the marker BPDUs are not initiated, only forwarded when received, resulting in the Marker fields in the output usually displaying zeros.

switch# show lacp counters
LACP Port Counters.
               LACP      LACP      Marker    Marker    Marker     Marker
Port   Trunk   PDUs Tx   PDUs Rx   Req. Tx   Req. Rx   Resp. Tx   Resp. Rx   Error
----   ------  -------   -------   -------   -------   --------   --------   -----
A2       A2    1234      1234       0          0         0         0           0
A3       A3    1234      1234       0          0         0         0           0