Re: LVS-NAT - will this work?

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: LVS-NAT - will this work?
From: Joseph Mack NA3T <jmack@xxxxxxxx>
Date: Fri, 19 May 2006 04:47:46 -0700 (PDT)
On Thu, 18 May 2006, John Oliver wrote:

I'm looking to implement an LVS solution into an existing network with
zero downtime.

hmm, I see.

Yes, it's messy.  But I need to do something like this because there's a
lot more going on on this network than just the stuff I want behind an
LVS.  I can't help but think, though, that traffic returning from the
realservers would have the source IP of eth0 instead of eth0:1


I assume you have two IPs on the realservers for other reasons. Possibly you're adding the extra IP on eth0:x
to setup the LVS.

The reply packets will come from the IP that the service is listening to. If you don't do anything special (anything special = using xinetd and have the demon listen on the IP of eth0:x), then the service will bind to and reply from the IP on eth0. You could have the service listen to and in your ipvsadm rules send to the IP on eth0:x. That should work. People bind the service to lo:x for the VIP in LVS-DR all the time.

All of the early parts of the HOWTO, like you used for your ascii art, were written when ethernet aliases were in use. Now it would be better to use the iproute2 tools to put on the two IPs. Doing it this way both IPs are primary IPs in the sense that the IP you have on eth0 is a primary IP.

In this case the ethernet aliases should work, but if you can't get it to go easily, then try adding the IPs with iproute2 tools (the IPs you add will be invisible to ifconfig).


Joseph Mack NA3T EME(B,D), FM05lw North Carolina
jmack (at) wm7d (dot) net - azimuthal equidistant map
generator at Homepage It's GNU/Linux!

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