Solved

Causes of noise

Posted on 2004-04-15
4
239 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
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

Netscaler Common Configuration How To guides

If you use NetScaler you will want to see these guides. The NetScaler How To Guides show administrators how to get NetScaler up and configured by providing instructions for common scenarios and some not so common ones.

Question has a verified solution.

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

Suggested Solutions

Title # Comments Views Activity
Cisco switch suggestion 5 65
Help logging in to my router 12 62
Setting out for Cisco UCS 2 25
MSSQL server connection  forced closed 3 38
Meet the world's only “Transparent Cloud™” from Superb Internet Corporation. Now, you can experience firsthand a cloud platform that consistently outperforms Amazon Web Services (AWS), IBM’s Softlayer, and Microsoft’s Azure when it comes to CPU and …
When it comes to security, there are always trade-offs between security and convenience/ease of administration. This article examines some of the main pros and cons of using key authentication vs password authentication for hosting an SFTP server.
Get a first impression of how PRTG looks and learn how it works.   This video is a short introduction to PRTG, as an initial overview or as a quick start for new PRTG users.
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…

830 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