CSMA/CD
CSMA/CD (Carrier Sense Multiple Access / Collision Detection) is the protocol used in Ethernet networks to ensure that only one network node is transmitting on the network wire at any one time.
Carrier Sense means that every Ethernet device listens to the Ethernet wire before it attempts to transmit. If the Ethernet device senses that another device is transmitting, it will wait to transmit.
Multiple Access means that more than one Ethernet device can be sensing (listening and waiting to transmit) at a time.
Collision Detection means that when multiple Ethernet devices accidentally transmit at the same time, they are able to detect this error.
How Collisions Occur under CSMA/CD
Imagine a very simple Ethernet network with only two nodes.
Each node independently decides to send an Ethernet frame to the other node.
Both nodes listen to the Ethernet wire and sense that no carrier is present.
Both nodes transmit simultaneously, causing a collision.
Both nodes detect the collision and each node waits a random amount of time before transmitting again.
Collisions are normal on an Ethernet network. A small amount of collisions are expected in the protocol design.
If too many nodes are transmitting on an Ethernet network, the number of collisions can rise to an unacceptable level. This can reduce the amount of available bandwidth on an Ethernet network because so much bandwidth is lost in retransmission.
Ethernet switches greatly reduce the already minor difficulties experienced with the CSMA/CD protocol.
|
|
Comments (19)
Leave a Reply
- Understanding Ethernet Networking
Ethernet refers to the family of Local Area Network implementation that was jointly developed by Digital Equipment Corporation, Intel Corporation and Xerox Corporation. It consists of certain specifications and standards as well as hardware devices and components. Ethernet Connection The Ethernet protocol provides for a verity of cabling options, one of which is a specification [...]...
- Ethernet
Ethernet is the most common LAN (Local Area Network) technology in use today. Xerox developed Ethernet in the 1970s, and became popular after Digital Equipment Corporation and Intel joined Xerox in developing the Ethernet standard in 1980. Ethernet was officially accepted as IEEE standard 802.3 in 1985. The term “Ethernet” is now used to refer [...]...
- Ethernet Splitter
An Ethernet splitter can split a single Internet connection so that two or more computers can connect to the Internet simultaneously. It can also create additional connections for other computers on a network, which can reduce the overall amount of cabling required to setup a network. Unfortunately, Ethernet splitters cannot resolve the network collision issues [...]...
- Ethernet Hub
For any two devices to be connected, they need a common place, or a hub, as it is called in the computer world. It basically connects multiple computers together. Most of the hubs available in the market today support Ethernet standards. This is why they are called Ethernet hubs, and are most commonly used in [...]...
- Ethernet Switch
A switch is something that is used to turn various electronic devices on or off. However, in computer networking, a switch is used to connect multiple computers with each other. Since it is an external device it becomes part of the hardware peripherals used in the operation of a computer system. This connection is done [...]...
Its a simple explanation, very instructive. thanks
I understood it clearly. Thank u for the explanation.
great, thanks!
It’s really good. Thanks
its really helpful man, thanks a lot.
it is really too helpfool…Thanks a lot..
good but further more detail is required… for ex: how does the station listens to the channel and how does it know the channel is busy or used… and what kind of jamming error is woken
good explanation , very helpful thanks…..
it is very simple explain
Thanx a lot for sharing
Thanxx…a lot it was easy to understand!!!!
good but differentiate with cs ma/ca
thanks dude good explanation
thanks…
that was quite easy to understand !
unless CSMA/CA, CSMA/CD sends signals after collision had occured. What are other differences?
The explanation was in very simple words but was very good.
Thanks
great
but i need more deeply information
i also need more information……
Please tell me how a node listens to the medium that its free or not? or take it as ..how a node detects a carrier on the ethernet wire ? Please reply soon.