[ILUG] Heartbeat and intelligent switches

[Paul Jakma]

On Mon, 6 Jun 2005, Colm MacCarthaigh wrote:

> The most reliable way is to migrate the mac-address aswell, as part 
> of the resilience. We do this for all of our servers, and we have 
> 200ms failover with no problems. Though in our case we're using the 
> linux bonding driver.

Slightly different to L3 failover.

For bonding you do want L2 to balance, hence you want a shared MAC.

For L3 failover, your choices are:

- failover the MAC from one port to another
   (ie update MAC<->port state in the switch)

or

- failover the IP
   (ie update IP<->MAC state in hosts)

I'd pick the latter: L2 doesnt need to know, gratuitous ARP is very 
commonly used and perfectly portable across different OSes and it's 
switch agnostic (think: what if the backup port is on a different 
switch?).

regards,
-- 
Paul Jakma	paul at clubi.ie	paul at jakma.org	Key ID: 64A2FF6A
Fortune:
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