Using CARP with multiple IP aliases (FBSD 10.0)

[Steven Hartland]

----- Original Message ----- 
From: "Freddie Cash" <fjwcash at gmail.com>
To: "FreeBSD Stable" <freebsd-stable at freebsd.org>
Sent: Thursday, September 11, 2014 4:15 PM
Subject: Using CARP with multiple IP aliases (FBSD 10.0)


> Good morning,
> 
> Just looking for some clarification around the proper use of CARP on
> interfaces with multiple IPs.
> 
> I've been using the new CARP on FreeBSD 10.0 with great success on a pair
> of systems with lots of vlans across 3 physical NIC ports.  However, those
> systems only have a single IP per vlan.  The ifconfig lines are very
> simple, and everything just works the way I expect it to, failing back and
> forth between the two systems as needed.
> 
> I'm now trying to get CARP working on a second pair of systems, and running
> into issues with one of the physical interfaces.  I think I might be doing
> the ifconfig commands wrong, but the ifconfig(8) and carp(4) man pages
> aren't very clear on this usage.
> 
> Are all of the carp-related parameters required for every IP alias added to
> an interface?  Or are the pass/advbase/advskew only needed once per
> interface, and you just pass the vhid to each IP alias?
> 
> Currently, I'm doing the former and having issues with both boxes claiming
> to be master for that one interface.
> 
> Which is correct:
> 
> ifconfig igb0 inet 1.2.3.4/24 vhid 30 pass mypass
> ifconfig igb0 inet 1.2.3.5/32 vhid 30 pass mypass alias
> ifconfig igb0 inet 1.2.3.6/32 vhid 30 pass mypass alias
> ifconfig igb0 inet 1.2.3.7/32 vhid 30 pass mypass alias
> ifconfig igb0 inet 1.2.3.8/32 vhid 30 pass mypass alias
> 
> OR
> 
> ifconfig igb0 inet 1.2.3.4/24 vhid 30 pass mypass
> ifconfig igb0 inet 1.2.3.5/32 vhid 30 alias
> ifconfig igb0 inet 1.2.3.6/32 vhid 30 alias
> ifconfig igb0 inet 1.2.3.7/32 vhid 30 alias
> ifconfig igb0 inet 1.2.3.8/32 vhid 30 alias
> 
> Neither the ifconfig nor the carp man pages show examples with multiple IPs
> configured within the same vhid.

I believe you need a seperate vhid per IP assuming you want each to fail over
to another machine when it goes down e.g.
ifconfig igb0 inet 1.2.3.4/24 vhid 30 pass mypass
ifconfig igb0 inet 1.2.3.5/32 vhid 31 pass mypass alias
ifconfig igb0 inet 1.2.3.6/32 vhid 32 pass mypass alias
ifconfig igb0 inet 1.2.3.7/32 vhid 33 pass mypass alias 
ifconfig igb0 inet 1.2.3.8/32 vhid 34 pass mypass alias

    Regards
    Steve