Re: [lvs-users] Ldirector and swtich caching

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: [lvs-users] Ldirector and swtich caching
From: Graeme Fowler <graeme@xxxxxxxxxxx>
Date: Thu, 15 Jan 2009 16:49:46 +0000

On Thu, 2009-01-15 at 11:37 -0500, Brandon Hilkert wrote:
> Well, we haven't gotten to the heartbeat point yet. Right now, we have a 
> dedicated "backup" machine with exact same configuration both from a network 
> standpoint and ldirectord config that's in a powered off state. The hope for 
> the time being if something were to happen to the main Ldirector, was to turn 
> it off and power on the "backup" machine. In this case, I can see how ARP 
> issues would arise. Any thoughts on this situation?

When the machine brings up the VIP, you have to tell the router
*somehow* that the VIP has changed to a new MAC address. The easiest way
to do this is to use ping:

ping -n -w 10 -I $VIP $router_ip

In other words:
  -n : don't resolve names
  -w : run for no more than this many seconds regardless of results
  -I : bind to this interface

That *should*, ideally, tell the router that the MAC has changed. Note
however that you should only use this for a gateway on the same LAN; if
you;re doing anything clever (ie. with multiple routers) it may not work
at all. Also if you've got more than one upstream router (such as an
HSRP setup) then you'll need to ping all participating devices.



PS It's easier to use heartbeat or keepalived for this, trust me!

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