[lvs-users] LVS-DR UDP healthy check problem

Julian Anastasov ja at ssi.bg
Sat Dec 10 15:34:23 GMT 2016


	Hello,

On Sat, 10 Dec 2016, linbo liao wrote:

> Hi,
> 
> I want to setup an LVS-DR cluster using keepalived.  It will load UDP
> packet to real server.  Refer to
> http://kb.linuxvirtualserver.org/wiki/UDP_service_binding_issue_in_LVS/DR_and_LVS/TUN,
> UDP service in Real Server should be bind to VIP, but not to any
> address(0.0.0.0).
> 
> If UDP service can't bind to any address in Real server, how Keepalived to
> do healthy check?

	UDP application server can set the local address for
outgoing packets by using cmsg SOL_IP/IP_PKTINFO (ipi_spec_dst).
The used local address can be copied from the received request.
As result, binding to 0.0.0.0 should be possible. In any case,
listening to 0.0.0.0 and replying with correct local
address is a common problem for UDP servers and not
related to the fact that VIP is also configured on the
real server. If the UDP server does not use cmsg IP_PKTINFO
then the other solution is to bind 2 sockets, one to VIP
and another to RIP.

Regards

--
Julian Anastasov <ja at ssi.bg>



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