Solved

Causes of noise

Posted on 2004-04-15
4
249 Views
Last Modified: 2010-04-11
I would like to know what noise in a network is. Also its causes and perhaps remedies.
Thank you.
0
Comment
Question by:buduson
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
4 Comments
 
LVL 67

Accepted Solution

by:
sirbounty earned 25 total points
ID: 10831833
I believe you're referring to crosstalk.  It's basically interference from an outside source.  
Remedies include using proper cabling and/or higher quality cabling...

[Crosstalk] is caused by signal crossover resulting from poorly twisted, internal wiring
[Ambient noise] is caused by interference from an external source, such as another electronic device
[Attenuation] is caused by the degradation of a signal over the length of the transmission or as a result of crosstalk or ambient noise
ref: http://www.cdwg.com/webcontent/editorialg/networking/011503_Decipherthecablingpuzzle.asp

Crosstalk: A disturbance, caused by electromagnetic interference, along a circuit or a cable pair. A telecommunication signal disrupts a signal in an adjacent circuit and can cause the signals to become confused and cross over each other. ref: http://www.webopedia.com/TERM/C/crosstalk.html

ACR: Also known as headroom, attenuation crosstalk ratio (ACR) is the difference between attenuation and crosstalk at a given frequency along a cable. Measured in decibels, ACR is a calculation used in networking transmission to assure that a signal transmitted across a twisted-pair cable is stronger at the receiving end than any interference signals imposed on that same pair by crosstalk from adjacent pairs. ref: http://www.webopedia.com/TERM/A/attenuation_crosstalk_ratio.html
0
 
LVL 12

Expert Comment

by:RWrigley
ID: 10833170
Noise is anthing that disrupts the smooth flow of electrons (or light, if you're using Fibre) down the wire.

Most likely source is badly terminated CAT 5 wire.  Check where the cable enteres the RJ45 connector and make sure that the wires go all the way to the top of connector, and that there is a portion of the sheath underneat the crimp (so that you can't wiggle the cable back and forth in the connector).  Also, make sure that the cable was terminated properly...the second pair of wires should be split around the first pair.

Second most likely source is that someone ran the cable over a flourescnet light, or underneath a monitor, or beside an electric heater, or something like that.  Most inter-office networking is done with Unshielded Twisted Pair wire.  Being unshielded, its somewhat vulnerable to strong EMI (electro-magnetic interference).  The devices I listed above are all big EMI generators.

Also, make sure you're using CAT 5 or Cat 5e wire.  Cat 3 wire or lower won't support 100mb data properly, particularily over longer distances.
0

Featured Post

Online Training Solution

Drastically shorten your training time with WalkMe's advanced online training solution that Guides your trainees to action. Forget about retraining and skyrocket knowledge retention rates.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

If your business is like most, chances are you still need to maintain a fax infrastructure for your staff. It’s hard to believe that a communication technology that was thriving in the mid-80s could still be an essential part of your team’s modern I…
ADCs have gained traction within the last decade, largely due to increased demand for legacy load balancing appliances to handle more advanced application delivery requirements and improve application performance.
After creating this article (http://www.experts-exchange.com/articles/23699/Setup-Mikrotik-routers-with-OSPF.html), I decided to make a video (no audio) to show you how to configure the routers and run some trace routes and pings between the 7 sites…
This video gives you a great overview about bandwidth monitoring with SNMP and WMI with our network monitoring solution PRTG Network Monitor (https://www.paessler.com/prtg). If you're looking for how to monitor bandwidth using netflow or packet s…

732 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question