Introductory Article on Embedded Systems-Routers

Hello everyone,

The following article is a basic overview of embedded systems as they apply to routers. It was written as part of a college project for an introductory PC hardware course. We encourage you to read our article at the address listed below and we welcome your comments. Please let us know if there is anything that you think we should have included but didn't, or if there is anything that you think is inaccurate or inappropriate. Please keep in mind that this is not a highly technical review of the subject, but rather a brief summary. The article concentrates on the hardware used in routers rather than the software and includes a brief discussion on RISC architecture. We also discuss how an ordinary PC can be tranformed into a router.

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Outline:

-Embedded Systems

-Hardware -CPUs -RISC -MIPS -ARM -Memory

-Cisco IOS

-PC-Based Routers

Thank you,

Scott Drummond Devin Patel

Reply to
Scott Drummond and Devin Patel
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As a brief intoduction it is fine as far as it goes but I feel you may need to consider improving the depth of the material. Perhaps there is more to come?

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Paul E. Bennett ....................
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Reply to
Paul E. Bennett

Not that bad, but WAY to Cisco centric. IMHO only Cisco routers use CIOS - many others are also using their own or some flavour of Linux.

Just my 2¢

Markus

Reply to
Markus Zingg

Thanks for your comments Paul.

It is just supposed to be an overview of the subject. Since we are certainly not experts in the subject, we wanted to get some feedback from more knowledgeable people.

Was there any particular area that you thought needed more attention?

Scott Drummond

Reply to
Scott Drummond and Devin Patel

Thanks for your comments Markus.

I agree that Linux can be used, but I thought that it was only used with PCs and not dedicated routers (ie, embedded systems). Is this not true? Our topic was supposed to be mainly on embedded systems, so we didn't devote much attention to using PCs as routers.

Yes, our article was quite Cisco centric but aren't they the leading brand? Are there any other brands that you think we should have discussed?

Scott Drummond

Reply to
Scott Drummond and Devin Patel

To answer a question in your other response, there are also other players in the router market like Netgear, Interpoch, Welltech etc. I am sure that spending some time with Google will turn up a number of others. It may require some digging to find out what they run as an OS (if any).

Even though your article is an overview, I felt that the treatment was still very light and seemed to cover probably a page and a little. It is the sort of level that I would expect Secondary/High School pupils to be able to churn out with ease (even my son, who is 13, could do so). Perhaps applying yourselves a little more would get you a slightly more detailed analysis which, as an overview, would have been more illuminating. I was just left feeling that you hadn't really revealed anything new to me.

Now, I am not an expert in routers. However, even I am aware that various router products exist that support things like IEEE1588 with some leanings towards also supporting the requirements of LXI. You may not have come across those in your searches yet because they appear to be quite new facilities of the routers and Ethernet networking in general.

You could also have mentioned a bit about the general structure of routers and introduced routing tables and the fact that routers deal with security issues in a number of ways.

In short. Try harder and I will look forward to reading the improved version.

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Paul E. Bennett ....................
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Reply to
Paul E. Bennett

I agree that Linux can be used, but I thought that it was only used with PCs and not dedicated routers (ie, embedded systems). Is this not true? Our topic was supposed to be mainly on embedded systems, so we didn't devote much attention to using PCs as routers.

Reply to
Steve at fivetrees

There are dozens of "Wireless routers" using MIPS cpu's and wireless chipsets from Broadcom, all running Linux. The Linksys variations are the most popular (e.g., the WRT54G routers), but there are many different brands all based on Broadcom designs.

Their popularity is to some degree the result of using GNU/Linux, and releasing not just the specific GPL's software packages they are required to distribute, but also the entire software toolchain required to cross compile and generate a new system. They are inexpensive and fun, so people are buying them just to play with!

That borders on being an arbitrary division, and probably would be better stated as a line that you have chosen rather than trying to argue that it is some natural line in the sand.

I didn't have a problem with that as such. I guess there were limits on just how big you wanted your article to be, and of course everyone else would like to see "more", each of use with a different idea of exactly what "more" ought to be... :-)

I won't complain if you devote time to more research and expand it to twice, or even larger, its current size.

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Floyd L. Davidson           
Ukpeagvik (Barrow, Alaska)                         floyd@barrow.com
Reply to
Floyd L. Davidson

Scott,

Yes, Cisco is the leader by far in the enterprise space (corporations); a little less so in the consumer space (they own LinkSys now); in the ISP space there are many strong players.

While there's more to routers than Cisco, I think you'll find far more writen on Cisco's inner workings than any of the other vendors, so using them as an example is appropriate. For example, this book is excellent:

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It gives a really interesting look inside the architecture, queuing mechanisms, processes, etc. inside IOS. I can't say I've seen similar internal details for any other vendor.

Regarding Unix/Linux... it's more widely used in embedded systems that you realize.

For example, many of the popular Linksys router / firewalls are Linux-based, and their source is freely available under GPL:

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So, for under $60 you can get a pretty nice embedded system with wireless, and then customize it.

On the article... it's a good scratch on the surface.

Embedded is a pandora's box, and spans something like 95% of the CPUs sold each year, dwarfing the PCs that people perceive to be the computing market - it's a huge topic, as are many of the sub-topics you touched on. So, you could expand that article into an entire book and it'd still be missing aspects for some readers.

E.g., hard drive controllers, modems, microwave ovens, VCRs, TVs, remote controls, cellphones, wristwatches - look around, and virtually anything with some degree of intelligence is "embedded" with a microcontroller, and the range of features/capability/complexity is very wide. Your article will need to draw the line somewhere, and this will probably be dictated by the requirements of the assignment.

My two cents, Richard

Reply to
Richard H.

I thought that, with the subject title chosen by the OP, he had set himself a sensible boundary to work to. Of course, for the article to get more interesting than a mere "scratch at the surface" he does need to look a bit more into it than his initial posting. I am sure that there is a lot of interesting stuff on routers that, had we all got sufficient time, we would all research quite deeply. Instead, we hope to find a useful paper or book on the topic that gives us a reasonable view. Embedded systems in routers is quite an interesting topic given the breadth of just that little portion.

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Paul E. Bennett ....................
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Reply to
Paul E. Bennett

Thanks Richard for your comments and thanks to everyone else who commented. I really appreciate your advice. This topic is huge and trying to give a brief overview is not easy when you are learning it as you are writing it. The problem that I found when researching the topic was that, while there is a ton of information out there, it is usually very specific and detailed. This makes it easy to overlook a topic. You (Richard and the others) have openned my eyes to some of the areas that I missed.

Thanks everyone,

Scott Drumm> Scott Drumm> > I agree that Linux can be used, but I thought that it was only used

Reply to
Scott Drummond and Devin Patel

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