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backup link on two parallel networks


I am having intra web server connected to two parallel, one is on ethernet and other is on token ring. Both the network is connected to other four offices. The network connected to ethernet card is having T1 connection with other four offices and network on token ring is 56K dialup.

Now I have to make 56k dialup network as a backup network for T1 network.

Please guide me.

Lots of thanks in advance



Re: backup link on two parallel networks

You might have a look at HSRP; you can track an interface, such that if the T1 goes down the Token Ring router will then have precedence.


Re: backup link on two parallel networks

Standard design for DDR or dialer watch will do the job--if you link the TR and Ethernet routers and run a routing protocol between all the routers so the TR router can know of the T1 (and, therefore, when it needs to dial) and the Ethernet router can learn of the path via the TR dial backup.

If you don't want to do a proper design, you could also do the job with shell scripts and routed on the web server (configuring the web server as a dual-homed host with a single IP address, as described in chapter 3 of my book, High Availability Networking with Cisco, see my web site for more about my book and example listings). You would use RIP between the server and routers to implement dual homing, and a shell script to send "pings" to bring up 56K backup links as needed when T1's fail.

Hint: the server based solution is ugly and prone to mistakes. You would be much better off with a proper network design which provides dial backup for all users, not just your intranet web server.

Good luck and have fun!

Vincent C Jones

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