Server with multiple IP's - How do I I choose which IP certain traffic goes out on.

wasc · 5 Sep 2007 at 09:19

Ok, I have a SMTP server with multiple Smtp virtual servers on (part of MS IIS).

This server also has 4 IP's bound to it's network card. Lets say these IP's are;

60.61.62.63
60.61.62.64
60.61.62.65
60.61.62.66

Now *everything* this server sends outbound is on the first IP (60.61.62.63). Is there a way I can choose which traffic goes out on which IP (e.g one virtual server goes out on .63, another on .64 e.t.c)?

If I need to buy software to do this, then I would.

sidethink · 5 Sep 2007 at 10:13

Hrm, not sure about this really - in principle this is controlled byu your default gateway setting on your network card, and no matter how it appears, setting more than one DG can cause problems.

I *think* you can bind IIS virtual servers to only listen on certain physical interfaces but I'm not sure about what impact that would have on outbound traffic from those interfaces.

wasc · 5 Sep 2007 at 11:39

sidethink said:
Hrm, not sure about this really - in principle this is controlled byu your default gateway setting on your network card, and no matter how it appears, setting more than one DG can cause problems.

I *think* you can bind IIS virtual servers to only listen on certain physical interfaces but I'm not sure about what impact that would have on outbound traffic from those interfaces.

Hi,

You can bind IIS virtual servers to different IP's - this is what we've done, so an outside server connecting to say 60.61.62.63 on port 25 will get through to a different virtual server on the same machine than connecting to say 60.61.62.64

The problem is that all outbound traffic goes through the first IP on the nic, i.e all outbound traffic goes through 60.61.62.63. We want to have more control over this

sidethink · 5 Sep 2007 at 13:21

I'm pretty sure its not something that the Windows TCPIP stack can handle. If your traffic was coming to/from a defined subnet, you could setup static routes to direct certain subnet-based traffic to certain interfaces but I guess that this solution is somehow internet facing and that would be impossible to do.

May I ask what you're trying to accomplish by doing this? Its not something I've ever seen done myself.