[lvs-users] DNS LVS questions

Graeme Fowler graeme at graemef.net
Thu Sep 6 12:43:56 BST 2012


On Thu, 2012-09-06 at 13:11 +0200, Jesper Dangaard Brouer wrote:
> This is not caused by IPVS.  The solution is that your DNS server must
> UDP bind/connect to the VIP, not the real-server IPs.

The easiest and most trivial way to resolve this is a requirement of the
LVS-DR method - to have the VIP(s) bound to loopback interfaces as /32
addresses (as interface aliases, or using "ip address add $VIP/32 dev
lo").

If they then become active on an ethernet (or other) interface with a
longer netmask, the nameserver daemon is already listening on that
address so service continues with no interruption. When that interface
goes away (on IP failover, for example) the address remains on loopback
so the service continues once more.

Graeme





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