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Functions Of Communication Protocols |
Communication Protocols:
Communication protocols is a system of rules for sending block of data from one node to another node in a network.
It provides services in the form of layer such as OSI Refrence Model.
All machine based communications must follow a certain set of
rules for the exchange of data between nodes connected to a network. The rules to
send and receive data are called protocols. These rules are defined in the
network software. A protocol defines;
Which is communicated?
How it is communicated?
When it is communicated?
1. Syntax:
Syntax refers to the format or structure of data. The protocol accepts the data
according to the predefined format. For example, a protocol may expect the
format of data as;
First 8-bits of the stream to be the address of the header.
Second 8-bits of the stream to be the address of the receiver.
The rest of the stream to be the actual data.
2. Semantics:
Semantic means mourning. Semantics refers to the meaning of each
section of the bits stream. It includes: how is a particular pattern of bits to
be interpreted, and what action is to be taken based on that interpretation.
3. Timing:
Timing refers to:
When data should be sent?
How fast it can be sent?
Functions
of Communication Protocol:
The data transmission software or protocols perform the following functions for the efficient
and error free transmission of data.
Data Sequencing: The function of a protocol to divide the long
message into smaller packets of fixed size that are to be transmitted for error
free data transmission, is called Data Sequencing.
Data Routing: The function of a protocol to find the most
efficient path or route, between the sender and the receiver before sending the
data is called Data Routing.
Flow Control: The function of a protocol to control the rate of
data transmission from the sender to the receiver is called Flow Control. It
regulates the process of sending data between fast sender and slow receiver.
Error Control: The function of a protocol to detect and recover
errors for successful data communication between the sender and the receiver is
called Error Control. Successful data communication means that data is
transmitted without any error.
Important Communication Protocols:
The most common and popular communication protocols are:
1. Ethernet:
Ethernet is the most popular and commonly used LAN protocol. Ethernet is based
upon bus topology, but can also be used in the star topology. It uses cables to
transmit data. This protocol is very simple than other, protocols. It is easy
to install and maintain.
All nodes (or computers) in Ethernet use the same cable for
sending and receiving data. Therefore, this type of network must follow a set
of rules to communicate the computers with each other. Otherwise it may cause
loss of data or messages. Before transmitting the data, a node must find out if
the cable is in use. If so, the node must wait. When the cable is free, the
node must begin transmitting immediately. Another version of Ethernet called
Fast Ethernet is 10 times faster than original Ethernet. Gigabit Ethernet is even
10 times faster than Fast Ethernet.
2. Token Ring:
Token ring is another widely used LAN protocol. It is used in
local area network using ring topology. A computer in the network (using ring
topology) must get a token to transfer data to another computer on the network. A
token is a special electronic signal. It consists of a series of bits. It is
like a ticket. Only one token is available on the network.
When a node on the network wants to transmit data, it first gets
the token, and then it can transmit data. When the node has sent its message,
it releases the token back to the network. This method of controlling access to
the shared network cable is called token passing.
In the token passing scheme, only one device is able to access the
network at a time. Thus, no collision can occur. The main disadvantage of this
scheme of data exchange is that, it has very slow data transfer rate.
3. Transmission Control Protocol:
Transmission Control Protocol / Internet Protocol is a real
communication protocol that drives the Internet. Every computer to access the
Internet must be installed TCP/IP. This protocol provides connectivity between
browsers and servers on the Internet for data communication.
TCP/IP ensures a reliable connection between the computers
communicating over the Internet. It also defines a mechanism through which
every computer on the Internet is identified separately.
In this protocol, data transmission is managed by dividing the
data into different pieces called packets. Each packet of data contains a part
of the actual data, source computer's address, destination computer's address, and
information for reassembling data at the destination computer. These packets of
data travel along the fastest available path in the network.
4. Wireless Application Protocol (WAP):
Wireless application protocol is used by mobile users to access
the Internet and e-mail services. On WAP, client-server network architecture is
used. Mobile device uses client software. To connect to the server computer by the Internet Service Provider
(ISP). Mobile devices that support WAP are called WAP-enabled devices. The
demand of WAP-enabled devices is increasing day by day.