CARP + LAGG + Switch Stack

  • I need confirmation on the behavior of CARP before I deploy in two weeks.

    Unfortunately I am unable to lab this up as this will be a hot cut with the existing equipment.

    The question is simple, if one of the stacks goes offline, and there's a LAGG between the CARP hosts and the stack across both switches (SW1 port 1, SW2, port 1).. what happens to the CARP state? That is, since it will detect a physical port failure on one port in the LAGG, will it start flapping between CARP hosts?

    My intent was to create a highly available solution between the CARP hosts and the switch stack by connecting across both stack members, but if that is going to cause issues, I'll probably put the primary CARP host on a LAGG w/SW1, and the secondary CARP host on a LAGG w/SW2.

    I'd rather have my switching fabric fail and lose half of the LAGG than a CARP state change, but if this is the only way that's fine too.

  • Rebel Alliance Developer Netgate

    If the CARP VIP is on the lagg interface, the link status of the lagg and thus CARP VIP should only flip if both NICs die.

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