On 6 Jun 2005, at 14:36, Colm MacCarthaigh wrote:
> On Mon, Jun 06, 2005 at 01:49:35PM +0100, Niall O Broin wrote:
>> I realise that without more details about the networking
>> infrastructure, which I don't currently have, it might be hard to say,
>> but I'll ask anyway. In general, can this cause a problem, and if so,
>> how can it be obviated?
>> 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.
That thought had occured to me, but as far as I understand, the problem
this organisation has is with the packets from the same IP addresses
coming in on different ports. However, I could well be misinformed.
This is for a large European organisation, and on occasion, getting
accurate technical information through the layers can be a tad tricky.
> If this isn't an option, then the very least the failover should do is
> to trigger a few outbound packets to the gateway after failover occurs,
> to give the network a chance to learn the new MAC address.
That's a plan - I must do that.
> After that, if the switches/gateway don't play nice, it's arp-timout
> tuning time :/
Which amounts to saying - "We have an application level issue, and to
solve it, you're going to have to change the network configuration". If
I felt that bloody lucky, I'd buy lottery tickets, and to hell with the
> That said, it mostly just-works these days.
I hope so. It looks like some testing will be in order anyway -
trivially easy to test of course, but we might be able to get a few
quid out of them for it anyway :-)
One part of the organisation wants to have a very important system made
highly available, so it's a question of persuading the other part to do
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