Buffering a WEB Farm

Major US corporation WEB Farms are being buffered by the NSC line of NATs. Why? Because they provide security without the complex setup that other firewalls or routers require. With the NSC NAT as a firewall, you specify the services that you wish to offer, rather than try to list all the ones that you don't want.

Virtual WEB Servers

Another function provided by the NAT is re-mapping of inbound service requests to the actual server on the inside. This lets you:

Hide the real addresses of your servers,
Have multiple servers on hosts that don't support multi-homing,
Distribute your service load across an array on internal servers,
Switch to a backup server easily.

Hiding your Real Addresses

You may use any addresses you wish on your private Intranet using our NAT. The outside world sees the IP Addresses that you want them to see, not your internal ones. This lets you move functions around or renumber your world without a change being noticed.

Multiple Servers on Simple Hosts

Not every WEB server or server platform will support serving multiple IP Addresses at the same time. For those that won't, the NSC NAT may be configured to make it look like they do. The NAT looks for service requests on as many as 32 different external IP Addresses, and then re-maps those requests into the private Intranet where the servers are. It doesn't just re-map the IP Address, though. It can also re-map the port (or service) number. This lets you run multiple servers on a single machine, using different port numbers for each, and then let the NAT make it look "right" to the outside world. We have details in our techie discussion page.

As an example, the Internet thinks this server is running NCSA httpd Version 1.4.2 on IP Address 138.113.2.4 and port 80. The server and version are right, but it is really using the RFC 1597 Address 192.168.32.7 and running on port 8002. Its backup is on 192.168.32.8 on port 8005.

Distribute your Service Load

This distributes incoming service requests (like to your Web server) across an array of up to four internal servers, giving you four times the power without having to purchase expensive multiprocessor platforms.

Switching to a Backup Server

The actual identity of your Web server is known only to you and to the NAT. If you have a server failure, and have the same information available on a backup server, you may switch to that backup server simply by telling the NAT that the actual server has moved. This amounts to a single command to the NAT, and is a lot easier than reconfiguring your backup server. Your backup server may even be one of your other production servers, which may be pressed into backup service without any configuration changes!

This page was last modified on April 19, 1996.

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