Re: [Xen-users] Live Migration with IPs?

[Mark Williamson <mark.williamson@xxxxxxxxxxxx>]

> Can someone explain how a cluster works when dealing with the IP
> addresses during a live migration?
>
>
>
> Say I have a class C, 192.168.1.0/24, with 10 physical servers and 5 VMs
> on each physical server for a total of 50 domU.  Each domU has 3 IPs.
> My question is, do I need to setup each physical server with all 150 IPs
> and bridge only the ones needed at that time for the running VMs?

When a domain migrates to another host it'll send a gratuitous ARP to say "I'm 
over here now" so that other network elements can reconfigure.

In the local area, the normal case is that things will "just work" - unless 
your bridge is doing some kind of sophisticated filtering, it should be 
perfectly happy dealing with a migration.

Worth noting: migration traffic is unencrypted (and as far as I know is 
unauthenticated), and therefore migrations are sniffable / tamperable / 
abusable (e.g. by other domains and machines on the LAN).  If this is a 
concern you'd need to take additional precautions e.g. having dom0s talk on a 
separate management VLAN (or physical LAN).  You also need to make sure that 
you use an appropriately secure interface to control your Xends.  Obviously, 
if your domUs are not considered hostile then this problem is somewhat 
simpler!

Cheers,
Mark

-- 
Dave: Just a question. What use is a unicyle with no seat?  And no pedals!
Mark: To answer a question with a question: What use is a skateboard?
Dave: Skateboards have wheels.
Mark: My wheel has a wheel!

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