I have a single internet T1 purchased for use by a single website that we run so it's traffic is never impeded. That website is running on our main web server with about seven other websites. Each website on the server has it's own IP address assigned to it. There is an external IP static mapped through the firewall directly to that website's assigned IP.
I have a second 3Mb internet pipe that is used for all the other website traffic and the general office surfing. When I look at the traffic on those pipes the single T1 is only getting about 2% usage and the 3Mb pipe is around 80% usage. What is surprising is that the single T1 is getting so little usage because it is a highly used customer site that they push a lot of traffic across. Then I got to thinking that there may be a deeper problem and that's where I need help.
The websever has a single NIC with a static IP (192.168.1.5) and then there are additional IPs assigned to it for use by different websites (192.168.1.100-120). On the firewall a static mapping is created that ties a website IP to an external IP. That's fine for incoming traffic but doesn't all outbound traffic use the IP of the server NIC? I think that's where my problem lies.
Inbound traffic is coming in on the single T1 pipe because the isolated website's IP (192.168.1.105) is static mapped to an external in the range assigned to that single T1, but when the outbound traffic for that site is exiting the network it is using the server IP (instead of the website IP) and therefore the outbound traffic is going out over the 3Mb pipe. Does that sound right? I know it's a bit confusing and I'll clarify if needed.