Question : Redundancy between two ISPs

Hi. First time, so please bear with me.

I have 4 Windows 2000 servers in my network of about 40 users. One of the Server is an Exchange 2000 Server, the other runs SQL, the third is a file/print member server and the last server is a Windows Terminal Server

We currently have DSL as our Internet pipe to the outside world

Our firewall is a PIX 515E. This also functions as a site to site VPN terminating server with our ASP (remote). This allows nightly database updates to the SQL server.

My issue...

We are moving from DSL to Frame Relay (786k). Since we have become so dependant on the availability of the Internet, we would like to have Cable as our seconday/backup link. These services are from two different ISP's (TDS and Time Warner). We will have static IP addresses from TDS for the Frame Relay (/29) and one Dynamic IP address for the Cable.

a. What hardware/software configuration is required to enable this kind of redundancy with the hardware that will be installed by the vendors. With this solution is it possible to have load balancing when both links are active or does the backup link (cable) sit idle when the Frame is active?

b. Since the Frame and Cable are from two different ISPs, what happens to my IP Addresses (assigned to MX records for my Exchange, External interface of the PIX and my Terminal Server) when the Frame goes down.

Thanks

Answer : Redundancy between two ISPs

You'll have to put a router out in front of your PIX to do the translation from Ethernet to Frame-relay, and a cable modem for the cable that hands off Ethernet. If you get a router that has at least two Ethernet interfaces and a serial for the frame, you can then do some semi-load sharing. Not true load balancing, but you can share the load and have failover at the same time. In-bound traffic is a whole 'nother story if you have web servers or email servers that depend on inbound traffic.

You might look at something like the FatPipes Extreme. It does not replace your PIX because it is not a firewall.

http://www.fatpipeinc.com/xtreme/index.htm

Other references:
http://www.experts-exchange.com/Hardware/Routers/Q_20745106.html