Take the 2-minute tour ×
Server Fault is a question and answer site for system and network administrators. It's 100% free, no registration required.

I am taught that Twisted Pair cables are twisted to cancel interference. Now, I have a CAT-5e crossed over cable of approximately 2 M in length. I removed the cable's cover and untwisted the wires. Still I can see no difference in performance of my network of two computers. Why? If I want to introduce the errors how can I do so? Also is there a way to check Data Link Layer errors using some command?

share|improve this question

closed as not constructive by joeqwerty, Dave M, mdpc, Khaled, mulaz Mar 14 '13 at 11:00

As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance.If this question can be reworded to fit the rules in the help center, please edit the question.

1  
... and why are you embarking on this crazy adventure of trying to break your ethernet layer? –  Jeff Ferland Mar 13 '13 at 13:53
    
I just want to learn sir! Thanks for the answer! –  DDC Mar 13 '13 at 13:57
    
@JeffFerland Can you suggest some tool for Windows using which I can check crc-32 errors? –  DDC Mar 13 '13 at 14:10
    
You'll probably don't see much of a difference in such a short cable stretch. Besides, the whole sheating business is to diminish external electromagnetic interference, as long as you don't have any such source nearby (a fluorescent tube does nicely) you again won't notice anything. –  vonbrand Mar 13 '13 at 14:14
    
@edDij 'netstat -e' can show you interface errors in windows, but its not specific about what type of errors they are. –  cpt_fink Mar 14 '13 at 5:32

2 Answers 2

.. approximately 2 M in length. I removed the cable's cover and untwisted the wires. Still I can see no difference in performance of my network of two computers. Why?

You probably don't have errors because of the relatively short length of the cable. The longer the cable length, the more attenuation of the signal intended signal and greater build-up of undesirable signal. The maximum spec'd distance of Ethernet is 100 meters, so at 2% of that, you probably haven't a sufficiently bad enough cable.

Using a longer cable, introducing an electromagnetic source of interference through inductance, or using a lousier cable (CAT 3 / phone cord) may cause more errors.

Errors are detected using a CRC32 of the ethernet frame. On Linux, you should be able to see any errors detected at this level by using ifconfig

share|improve this answer

You'll need longer cables. I've had many problems (mostly packet loss) with wrongly crossed cat 5 cables (direct 1 to 1 wiring scheme and not any one of standarts like http://www.washington.edu/lst/help/computing_fundamentals/networking/schemes) with lenght about 30-50 meters. Try this)

share|improve this answer

Not the answer you're looking for? Browse other questions tagged or ask your own question.