Etherchannel - fast-switchover

When creating an EtherChannel bundle using the LACP as the LAG protocol, it is possible to enable 1:1 link redundancy using the lacp fast-switchover command.

This command will essentially result in sub-second failover delay for an EtherChannel link when activated.

Prior to entering the lacp fast-switchover command, you must ensure the following:

• The port channel protocol type is LACP.
• The lacp max-bundle 1 command has been entered on the port channel.

Note that the recommended setup is to configure only two ports in such a bundle, where one will act as active, and one as hot-standby for optimum performance.

This is why the lacp max-bundle 1 command is recommended. For more info on this command, take a look at EtherChannel - max-bundle.

Links:

https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/cether/command/ce-xe-3se-3850-cr-book/ce-xe-3se-3850-cr-book_chapter_00.html#wp3841090550