This seems to be a pretty good intro into the subject, plus it also discusses another technique, not really very popular anymore, called "token passing."

http://www.omnisecu.com/basic-networking/network-access-methods.php

(Token passing was used in ring buses, such as IEEE 802.5 and FDDI.)

Note that the CSMA/CD protocol, which was made popular by the original coax, shared Ethernet (and is also very similar to the CSMA/CA protocol used in WiFi), is not actually used much anymore. Modern Ethernets have gotten away from that shared medium idea, and are now designed to connect each host directly, over a dedicated link, to a port of a multi-port bridge.

So in practice, each Ethernet host now transmits whenever it has anything to send. No wait necessary. Within each "switch," i.e. at those multiport bridges, there is a basic frame switching fabric, which either floods each frame to every other port, or in the case of unicast transmissions, after having learned the direction to a particular other host, the switch will know to forward frames addressed to a particular MAC address to just one other port, through the switching fabric.

Is there any remnant of CSMA/CD? Optionally, yes, but only between one host and its dedicated switch port. Optionally, if a host is configured to use "half duplex protocol," you'll see CSMA/CD at just that one interface. So in reality, there won't be a lot of opportunity for collisions, except for just traffic between that one host and its switch port. The only possible collision, in this case, would be between a frame the host is sending right now, and a frame the switch is sending back to that host, right now.

But if you select full duplex mode, there will be no hint of CSMA/CD anymore. Just transmit whenever you have to, and also receive whenever something is arriving. Any contention for the interface is managed by queues in the switch fabric.

There is also an optional PAUSE protocol now, used to reduce the queue lengths in switches. It's a bit of an afterthought. In short, PAUSE gives the sending host responsibility for building up its own queue, if the switch is unable to process the frames fast enough. This merely reduces the need for switches to build up queues, when congestion occurs.

Hello Jorcy,

CSMA means you can sense the link to check its states (free or busy).

The collision detection (CSMA-CD) technique is used only if collisions can be detected. Typically in the IEEE 802.3 (wired Ethernet) collisions are detected by stations.

In the wireless network, collisions can not be detected easily. To solve this problem the protocol tries to avoid collisions (CSMA-CA). But be careful, there are many "persistent" versions of CSMA (see . Kleinrock DOI: 10.1109/TCOM.1975.1092768). An implementation of this mechanism can be found in the IEEE 802.11. But the standard uses an improved version of CSMA-CA to  deal with the problem of hidden machines, by exploiting the RTS/CTS mechanism (see. MACA : a new channel access protocol for packet radio).

For CSMA-CD see:

http://www.ciscopress.com/store/ccent-ccna-icnd1-100-101-official-cert-guide-9781587143854

For CSMA-CA see:

http://www.ciscopress.com/store/ccna-wireless-640-722-official-cert-guide-9781587205620

Yes. Almost of network books, like Networks book, wrote by: tonembum.

Due to wireless environment CSMA-CD can not be used so CSMA-CA will be used to allow station listen before transmit.

For more information see the following links:

http://www.differencebetween.net/technology/protocols-formats/difference-between-csma-ca-and-csma-cd/

http://ieeexplore.ieee.org/xpl/articleDetails.jsp?arnumber=5515401

https://www.youtube.com/watch?v=RKkxKG5usaw

http://serverfault.com/questions/452675/what-is-the-reason-csma-cd-cant-be-used-on-a-wireless-network