By
Raul Bernardino
Introduction:
All communication occurs
on any type of networks and all involved parties must use a common
language. In the Information Technology (IT) networks, this is known as a
protocol. There are many different protocols that are available for
computer networks. The most common and widely used being TCP/IP.
TCP/IP is the standard
protocol that is being used on the internet whereas allows any network to access
the internet and therefore you must use the TCP/IP protocol suite. In other
hand an Active Directory required CP/IP. For that reason, TCP/IP is developed
and as a default protocol starting from Windows XP and server 2003.
Protocols
This protocols reference
is often made to the TCP/IP stack. This consists of layers of mini applications
which are performing the discrete job of sorting and filtering the data
packets picked up by the Network Information Center (NIC) and then passing the
packet on to the next layer for further processing. Eventually a coherent
message pops out of the top of the stack into the operating system for the user
to read. The reverse is also true i.e. converting of the reply into data
packets that can be sent over the network media.
The layers in a TCP/IP
stack write headers for network messages as well as decoding them. Each
level in the stack adds a portion to the network packet which its counterpart
in the receiving computer will understand. Strictly speaking, the NIC
isn’t part of TCP/IP, but protocols are bound to a particular adapter.
At the receiving
computer, the headers are stripped off as they pass up through the TCP/IP
stack until only the bare payload is presented to the user.
The DOD Four Layer Model
TCP/IP is often referred
to as the TCP/IP protocol suite. TCP/IP is in fact a group of
protocols/applications working together to provide network communication.
TCP/IP was invented by the US Department of Defense (DOD) to allow machines to
communicate over a network. It is a simpler model than the 7 layer OSI
model. The different components of TCP/IP all function at different
layers. These layers group the different components into four different
categories.
The Application Layer
The application layer
contains the applications that use TCP/IP such as Internet Explorer, chrome,
safari, Netscape, and Outlook. The application layer also contains
Application Programming Interfaces (API) such as Winsock, which enables
applications to use TCP/IP.
The Transport Layer
The transport layer is
responsible for the transfer of data on the network. There are two
different transport protocols TCP and UDP. Both protocols provide transport but
it works in different ways.
Transmission Control
Protocol (TCP)
TCP is a
connection-orientated protocol. Both sides (end to end) confirm that the data
is being sent and received.
User Datagram Protocol
(UDP)
UDP is a
connectionless-orientated Protocol. Both computers presume the other side has
received the data. As an example, name resolution uses UDP. If the query
fails then a TCP name query is made.
The Internet Layer
To send data the sender
must have a method of distinguishing the recipient. This is called an IP
address and they take the form of a unique number on the network. The Internet
Protocol is responsible for these addresses. The Internet Control
Messaging Protocol (ICMP) is used to test connectivity between machines by
sending ICMP messages using the PING command. The Internet Group
Messaging Protocol (IGMP) is used to send data to groups of machines, e.g.
Streaming Video. This is known as Multicast. The Address Resolution
Protocol (ARP) is responsible for changing an IP address into the network
card’s physical address. Every network card has a unique physical address
hardwired into the card itself which is needed for communication on a network.
The Physical Layer
The physical layer is
responsible for the actual physical media and how the data is sent to another
machine, e.g. Fibre Optic, ATM. There are many ways to send data down the
cable, the most common technologies for LANs are Token Ring and Ethernet. In
order for two machines to communicate they must be using the same technology or
be connected via a bridge.
Reference list:
Wiki, (n:n) Network Interface Controller, [On-line].
Available from: http://en.wikipedia.org/wiki/Network_interface_controller
(Accessed: 20 October 2014)
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