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12/13/2000 -- If you're preparing for the CCIE lab or just want to get some equipment for the home lab to practice the concepts covered in BCRAN, I've discovered something. You can buy two routers with ISDN capability for less than what it would cost for an ISDN simulator. The latter is a device that simulates the phone company network so your two ISDN devices can talk. The problem is that when it comes to the 2500 series of router, you need an external NT1 or a simulator with the NT1 built in. If you go with the popular Teltone model, this will set you back over two grand in most cases.
Your other option is to buy routers that come with serial ports that can switch between Synchronous and Asynchronous mode. The only problem with that is that the lowest model that comes this way is the 2520. Many people buy these for use as frame relay switches so they get pricey as well.
There's one last possibility for the despairing lab rat on a budget. If you take a look at a 2501, you'll notice that the device has two synchronous serial ports, one Ethernet, a console and an auxiliary port. You may not be aware that the Aux port is also an asynchronous serial interface! Strictly speaking, you have three serial interfaces on that 2501. How does this help? If you're out to practice Dial On Demand routing tasks and aren't picky about doing it over ISDN or analog, here's your chance to save some big bucks!
Here's what you'll need to handle DDR on the cheap. All of these were eBay prices, so you should expect them to vary. You don't need to buy USR or Viking equipment; this is just what I bought. Teltone makes some nice simulators for POTS but the basic ones normally run over $100 used.
- 28.8k External US Robotics Sportster, $20
- 28.8k External US Robotics Sportster, $25
- Viking DLE-200 2-port Telco Simulator, $65
In addition to things like telephone cords and rollover cables, you'll need a pair of RJ-45-to-male-DB-25 adapters. You'll use these to connect the rollover cable from the router to the modem. You can get one by ordering Cisco part CAB-5MODCM/MODEM or you can make one yourself using the pinout diagram found at http://www.cisco.com/univercd/cc/td/doc/product/access/acs_fix/cis2500/2509/acsvrug/cables.htm.
Once you have the gear together, you need a configuration. Here's where things get difficult, dealing with "chat scripts" and modem commands. If you're studying for the Lab, you need to learn these things at some point anyway. The cool thing is that once it's set up and working, you can practice stuff like dial backup and snapshot routing just like with ISDN. The difference is that when you're done, you saved $2,000. A down payment on a new sports car is more fun anyway.
For an example configuration using the AUX on both ends to communicate via modem, visit http://www.cisco.com/warp/public/779/smbiz/service/configs/async/async_ip_static_aux.htm. 
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