[Xymon] Listening on Mulitple IPs

[Jeremy Laidman]

On Fri, Nov 4, 2011 at 5:23 AM, Chris Ahrens <chris.ahrens at macys.com> wrote:
> My Xymon server has 3 IP addresses that I want to spread out my incoming
> status messages on.  I did not use the --listen so that xymond would come up
> to use 0.0.0.0:1984 and netstat shows it listening on 0.0.0.0:1984, but when
> I look at the network traffic 99.9% of it is on eth0.

Is that incoming or outgoing or both?  I believe outgoing traffic will
route via the "primary" interface regardless of the interface on which
it arrived, unless you have policy routes in place.  So you might have
a spread of incoming packets among interfaces, but all outbound
packets from a single interface.

> My client servers are using the dns entry of the Xymon server and dns has
> all 3 IP addresses of the Xymon server associated correctly.

Is it possible that your resolver is configured to deliver round-robin
records in fixed order?  Try an "nslookup" a few times and see if the
order of the 3 IP addresses is changing.  Also look at the TTL of the
records, to see if it's large, because clients might use the same
record for a period of time based on the TTL.  Also, try "getent hosts
<record>" a few times to see if the order is changing, as this will
indicate what the stub resolver is giving to resolver clients (such as
the Xymon client).

DNS round-robin is very poor for load-balancing.  It's not that great
for fault-tolerance either.  You might try using some kind of
interface-based traffic sharing, such as bonding.

Cheers
Jeremy