Communication Mode and Method

Communication Mode

 Half Duplex

• It uses only one wire pair with a digital signal running in both directions on the wire.
• It also uses the CSMA/CD protocol to help prevent collisions and to permit retransmitting if a collision does occur.
• If a hub is attached to a switch, it must operate in half-duplex mode because the end stations must be able to detect collisions.
•  Half-duplex Ethernet—typically 10BaseT—is only about 30 to 40 percent efficient because a large 10BaseT network will usually only give you 3 to 4Mbps—at most.

Full Duplex
 

In a network that uses twisted-pair cabling, one pair is used to carry the transmitted signal from one node to the other node. A separate pair is used for the return or received signal. It is possible for signals to pass through both pairs simultaneously. The capability of communication in both directions at once is known as full duplex.

Full duplex means you can send and receive at the same time. This was impossible on Coax, the original Ethernet media since it had only 1 conductor and Ethernet uses base-band signaling. However, 10BaseT and 100BaseT use a cable with 4 conductors.

Simplex Duplex

This communication mode is one way only. In this mode one host has data transmitted and other all hosts receive this data for which its sent. but these hosts could not communicate back with the sender. This is like broadcasting.

Television , Radio are the example of this mode.

Communication Method

There are three type of LAN traffic as given below:-
 
Uni-casting

This is one to one communication. In this communication Uni-cast frames are the most common type of LAN traffic. A uni-cast frame is a frame intended for one host. In this communication one by one host can communicate to each one. Phone communication is example of this method.

Multicast

In Multicast communication method, A group of devices has been defined that has common interest and after that multicast frames address to this group. Audio and Video Conferencing  are example of this method.

Broadcasting

In this communication method, Broadcast frames are intended for everyone. Host or devices view broadcast frame as public service announcements. all devices receive and process broadcast frames. In the large networks Broadcast can bring the network crawl, because every computer must process them.