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

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


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(
> 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 should be possible. In any case,
listening to 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.


Julian Anastasov <ja at ssi.bg>

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