Previous in Forum: Electrical Safety   Next in Forum: Avoiding Collision
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
10 comments
Rate Comments: Nested
izzyakm
Active Contributor

Join Date: Aug 2014
Posts: 13

Collision Question

08/14/2014 9:59 AM

hi, can anyone explained to me in detail how the collision occurs. I don't really understand if the router used csma/cd protocol "listen before transmit" how come there will be any collision? thank you
Register to Reply
Pathfinder Tags: collision csma/cd
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".
lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#1

Re: Collision Question

08/14/2014 10:21 AM

It didn't listen.
Register to Reply
izzyakm
Active Contributor

Join Date: Aug 2014
Posts: 13
#2
In reply to #1

Re: Collision Question

08/14/2014 10:23 AM

Really?
Register to Reply Off Topic (Score 5)
lyn
Guru

Join Date: Oct 2008
Posts: 42355
Good Answers: 1693
#3
In reply to #2

Re: Collision Question

08/14/2014 10:27 AM

Light travels really fast. Sometimes faster than the speed of sound. Maybe it just didn't hear the signal.

OK , I don't have a clue.
Register to Reply
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#4

Re: Collision Question

08/14/2014 11:02 AM

Because nothing ever really happens instantaneously and communication (&^$ can and will get interference.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Register to Reply
SolarEagle
Guru

Join Date: Mar 2007
Location: by the beach in Florida
Posts: 33392
Good Answers: 1817
#5

Re: Collision Question

08/14/2014 1:58 PM

Shared ethernet is obsolete, everybody went to switched ethernet....

...and tiny urls....

__________________
 All living things seek to control their own destiny....this is the purpose of life
Register to Reply
izzyakm
Active Contributor

Join Date: Aug 2014
Posts: 13
#10
In reply to #5

Re: Collision Question

08/15/2014 10:44 AM

Thank you, the link helps me alot
Register to Reply
3
Rixter
Guru

Join Date: Apr 2010
Location: About 4000 miles from the center of the earth (+/-100 mi)
Posts: 9910
Good Answers: 1141
#6

Re: Collision Question

08/14/2014 3:30 PM

There is a time interval between listening and sending. It is possible for another sender to be just a little ahead and start sending in this interval. Each sender then detects a collision and waits a random amount of time before trying again. If the network is lightly loaded, this occurs very infrequently. When the network is carrying closer to its maximum capacity, collisions become more frequent.
Register to Reply Good Answer (Score 3)
No more Good Answers.
izzyakm
Active Contributor

Join Date: Aug 2014
Posts: 13
#9
In reply to #6

Re: Collision Question

08/15/2014 10:43 AM

Thank you now i understand better.
Register to Reply
jack of all trades
Guru
New Zealand - Member - Kiwi Popular Science - Weaponology - New Member Engineering Fields - Power Engineering - New Member Engineering Fields - Electrical Engineering - New Member

Join Date: Sep 2006
Location: Auckland, New Zealand
Posts: 8777
Good Answers: 376
#7

Re: Collision Question

08/14/2014 3:48 PM

"Listen before transmit" only tells you no one is transmitting at that exact moment.

Think of it as looking down the motorway in heavy fog with limited visibility and then trying to cross on foot. Yes you checked before you started walking but before you get all the way across you get hit by a car that suddenly appears out of the fog.

The following link may also be of help.

http://en.wikipedia.org/wiki/Exponential_backoff

__________________
 jack of all trades
Register to Reply
izzyakm
Active Contributor

Join Date: Aug 2014
Posts: 13
#8
In reply to #7

Re: Collision Question

08/15/2014 10:41 AM

Thank you the link you give really a new thing for me to learn.
Register to Reply
Register to Reply
Have a Different Question?
10 comments

Good Answers:

These comments received enough positive votes to make them "good answers".
Copy to Clipboard

Users who posted comments:

izzyakm (4); jack of all trades (1); lyn (2); redfred (1); Rixter (1); SolarEagle (1)

Previous in Forum: Electrical Safety   Next in Forum: Avoiding Collision

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Communications & Electronics:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (179 right now)
Show Members
Advertisement