Re: Using ip_vs on different subnets

To: " users mailing list." <lvs-users@xxxxxxxxxxxxxxxxxxxxxx>
Subject: Re: Using ip_vs on different subnets
From: "Scott J. Henson" <scotth@xxxxxxxxxxxx>
Date: Wed, 20 Jul 2005 15:31:37 -0400
Joseph Mack NA3T wrote:

On Wed, 20 Jul 2005, Scott J. Henson wrote:

 As far as I can tell there is no way to do this.

it's the default in LVS. We've been doing it for years

Are you using dr, nat, or tun? As far as I can tell none of them work in the configuration. I think the difference is that the real server can direct route back to the client in all cases. This means that nat won't work because the packet goes back to the client instead of the director.

In dr and tun, the real server tries to send a packet back to the client with a src address of the VIP. This is normal, except in our case the routers along the way notice that the real server is trying to spoof the VIP and they drop the packet. This is espcially true when the client is on the same network as the vip. In that case the routers for that subnet see a packet with a src address that is internal coming in on the external interface and drop it as a spoofed packet(as they should). So I still don't see how this configuration would work. I can see how it would work if the RIP was on a private(non-routable) subnet, but in our case its not. If this is supposed to work I would love to hear it cause it would make my life much simpler. I'm just trying to confirm that this is a limitation in ip_vs and not a misconfiguration on my part. Thanks.

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