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ISDN Switch Simulator on the Cheap?
smartmux wonders: "I've starting working on earning a CCNA certification, and part of the requirement for this cert and the 'professional' level cert is to know and understand how to install ISDN BRI circuits. Getting the Cisco router equipment to configure is easy and relatively cheap, but real ISDN lines or an off-the-shelf ISDN simulator is way too expensive. I'm not a *nix guy, so I thought I'd ask here -- is it possible to take an old PC, a couple of ISDN network cards, and an open-source PBX (like Asterick maybe) and make a simple ISDN switch to let my two routers talk?"
I assume it's a written test anyway. So why would you need to know how to do any of this in practice anyway? Do you expect the others with this kind of certification to have any practical experience?
Cisco has been improving CCNA by giving the labs a little more depth, but they sure don't want to give up the ancient technology. This is my biggest beef with Cisco and their certification programs.
Who uses ISDN in a new installation anyway? These days you either go great guns with an OC3 or better between office locations or you use business/consumer grade DSL or Cable modem and VPN between office locations. I still hear of new T1 installations every now and then for certain critical uses where latency, security, and/or reliability are a huge concern, but they're still rare. ISDN is pretty much a dead horse. In fact many smaller telcos never did upgrade their switching equipment to even support ISDN in the first place. POTS, consumer broadband, and high-end DS1/DS3/OC3+ is where the action is at.
And I can tell you you dont have to know much about ISDN. Certainly dont need an ISDN switch..
I started studying for the CCNA by preparing for the CCNP. Thats how I study. I bought 2 1600 routers, 7 2500 and 1 2600 routers. Also got 2 switches and started working on them. Next I bought tonnes of old machines to remoteboot, load linux using PXE, and run gated to increase the number of 'routers' I had so I can just work on them and fix them, and therefore know all networking. I bought arcnet cards, atm cards and switches, fddi cards and switch, wireless stuff etc. Still studying for the CCNP.
The one thing I dont have is an ISDN switch. Its because its so god damn expensive for something that does so little. The pci-card-isdn-switch youll find on ebay is the cheapest one I've seen, at about 300. I DID buy a broken isdn switch... turned out to be a PRI switch, and requiring special windows software to work it, not available from ANYWHERE. I'd rather study for the voice stuff from cisco, theres more market for it anyway. Even those parts are expensive and require cisco 2600 and 3600 routers, each of which being expensive.
Studying at home for ccnp or ccie is not cheap. I tried to BUY an ISDN BRI line from Bell for a few months (should be cheaper than buying a switch), but they only continue their current installations. Most of their tech people had NO IDEA what ISDN is, and tried hard to sell me DSL. A T1 connection was expensive too, and download being slower than DSL!
Keep an eye on ebay. And just read up on the things you cant get hardware for, and rent a cisco stack a month before the exams. For all the basic stuff, 2500 routers should go a long way, even in the days of IOS 12.3.
"Give orange me give eat orange me eat orange give me eat orange give me you." -Nim Chimpsky
There are companies who rent time on systems that have all of the elements you might see on the test available. Here is only one of many examples http://www.thebryantadvantage.com/Rack%20Rentals.h tm/. Just do a google search for "rent time cisco ccna" and you'll have plenty of options appear. Probably a better use of time than setting up systems just for testing...but that's just my opinion.
There is a small company in Bothell WA that makes (or used to make?) a line of POTS, ISDN and T1 simulators as of at least three years ago. You can usually find their products on eBay for reasonable costs. Last I heard their products are quite good and have been used by other's in your position in the past. Peter
Firstly that's Asterisk not 'Asterick'.
Secondly if you have access to a telecomms switch that has ISDN BRI interfaces, then sure you can test to your hearts content.
Alternatively if you have links to any organisations that may have a few spare BRI interfaces you could always try to talk them into letting you borrow a few lines while you do your thing but with ISDN it's not like you can just use a 'crossover' cable or anything.
Well, you guessed right, Linux can do this!
A few links:
Linux 2.6 and mISDN HowTo
PBX4Linux
Have fun!
RFC1925
Why don't you get a small SoHo switch. Those are avaliable for about $200 and you can have up to 3 internal S0-buses which will talk Euro-ISDN.
Typical companies are Siemens or Telebau. A Telnet Willy 4ab from Telebau should be sufficient and somewhat cheaper than even the cheapest simulator.
I studied for my CCNA by taking a CCNA prep course at the community college. For the price, I got tons of hands on time with the hardware. What they also supplied was a program called Boson NetSim from http://www.boson.com/. Think of it as a entire network simulator. Drag and drop routers, terminals, switches, and connections, then click to log in to any of them. The simulated hardware behaved the same as the real hardware we had, the downside being that we didn't have to troubleshoot bad cables, or someone using a cross or roll-over cable when we needed a straight-through.
Other then that, I over studied for the CCNA. I made sure I knew ISDN inside and out, and didn't get a single question on it. Tons on EIGRP, though. Just remember that the test is pretty random, and bad luck says you will get questions on what ever part it was you don't study for.
Costs 300 Bucks, and has an ISDN Bus. And is nice SoHo Router with integrated VoIP capabilities.
Hands on is important and all but ISDN is a dead horse. There are many newer and better things out there now. At best you will see 1 or 2 ISDN questions and they will be basic questions. I got the CCNA back in 98 and as I recall there weren't more than a few ISDN questions back then! I'm sure the same goes for the CCNP/DP. If you go for the CCIE, then you need to know more. The fact that you are just now attempting the CCNA means that the CCIE will likely not be doable for another few years. By then ISDN may likely disappear form the test.
If you know these facts you should be more that prepared...
Data goes over 2 64kb B channels and there is one 16kb D channel handling signaling
There are two basic types of ISDN service: Basic Rate Interface (BRI) and Primary Rate Interface (PRI). BRI consists of two 64 kb/s B channels and one 16 kb/s D channel. PRI is intended for users with greater capacity requirements. Typically the channel structure is 23 B channels plus one 64 kb/s D channel for a total of 1536 kb/s. In Europe, PRI consists of 30 B channels plus one 64 kb/s D channel for a total of 1984 kb/s.
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