Do PAgP and LACP send keepalives

[ajsouthard]

Do PAgP and LACP send keepalives to monitor the segments in an etherchannel. If not, how do they know that a segment has gone down if there is an intermediate transparent device (ONS) that keeps the protocol up at the far end ?

[s.jankowski]

Take a look at the following link under "Overview of EtherChannel"

http://www.cisco.com/univercd/cc/td/doc/product/lan/cat4000/12_1_13/config/channel.htm

"If a segment within an EtherChannel fails, traffic previously carried over the failed link switches to the remaining segments within the EtherChannel. Once the segment fails, an SNMP trap is sent, identifying the switch, the EtherChannel, and the failed link. Inbound broadcast and multicast packets on one segment in an EtherChannel are blocked from returning on any other segment of the EtherChannel."

[ajsouthard]

Thanks for the info.

Unfortunately the document still does not describe how the failure is detected. It does not seem to be dependant on seeeing interface failure because we have an intermediate ONS device that keeps the interface up/up and yet the etherchannel "fails over" in less than a second.