Multipathing ethernet adapters?

[Adam Morley <adam-openbsd-misc_(_at_)_gmi_(_dot_)_com>]

Hi,

I've started using OpenBSD more at work, but one of the requirements 
we have is to provide failover between network switches.  Each system 
has at least two nics, plugged into two different switches that are 
stacked, or trunked, or etherchanneled, or whatevered together.  This 
means if switches fail, the server is still "accessible."  We also have
methods to failover the clients too.

We do this on Solaris using IPMP, which sets up n interfaces, only 
one active, with each having "test addresses" which send out ICMP 
probes to detect when a NIC fails (in addition to watching the link 
state in the kernel).  We also use Sun Trunking which does 802.3ad and
Cisco EtherChannel.

We do this on Linux using Intel's iANS package, which provides failover 
between NICs, using either Cisco's etherchannel, simple MAC failover 
(like IPMP above), load balancing, or 802.3ad trunking.

I provide the two examples above so in case my description is bad they 
will help.

I'm wondering what methods OpenBSD provides to do a similar thing.  I 
noticed the -mpath option in route(8), but I got the feeling it was 
more for multiple gateways, and not for multiple routes to the local 
subnet.

I also found CARP, but reading the man pages led me to believe (possibly 
incorrectly) that it was more for two hosts.  But it seems like it would
work for a single host too.

I also found "HAOS" (high availability OpenBSD Clusters) at 
http://insecure.dk/haos, but it doesn't seem to be done yet.

I'm basically looking for BTDT, to avoid too much dinking around.  But
if there isn't BTDT, I'll dink around.  ;-)

Thanks a bunch!

-- 
adam