On Wed, 24 Jan 2001, Andreas Brodmann wrote:
>
> On normal internetworking hosts, without the necessity of high availability
> this works fine. Not all hosts do update or even flush their arp cache with
> the same frequency though. Some have a cycle of less than one minute on
> routers on the other hand the default arp cache timeout is a lot higher which
> would force clients not in the same subnet to wait until the router flushes
> its arp cache until they can access your FreeBSD machine again.
> -> not ha compliant.
The time it takes to flush is very small. During that time the
router queue's up the request and waits for a reply. Once the
router has it, everything is transparent.
I would not recommend playing with MAC addresses at all. Switch
things using IP and let the ARP protocol take care of itself.
> There is a way to solve this problem by having a second interface in each
> cluster
> partner serving as standby interface. To this interface you assign the mac of
> its
> partner's interface and all its interfaces ip addresses.
>
> Just a hint: Have a look at scyld.com and Donald Becker's new Linux driver
> architecture. Many new cards allow for using more than one mac per card
> even without going into promiscuous mode. They can then be assigned to
> different subinterfaces. I don't know wheter the FreeBSD drivers support
> this. Anyway we still keep to the old fashioned way mentionned above, as the
> new Linux network driver architecture is not yet as stable as it could be, but
> once it is this would solve your problem.
I think this is a bad idea in a clustering enviroment. You are
taking the job of a switch and moving it to the card/software by
fiddling with MAC addresses on the hosts.
I guess I can see where this may be useful (trunking) but taking
over the MAC could cause problems...like duplicate MAC's etc,etc.
Of course, this is my opinion and I could be wrong.
Nick Rogness
- Keep on routing in a Free World...
"FreeBSD: The Power to Serve "
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