Page 33 - DCAP207_NETWORKS_DCAP406_COMPUTER_NETWORKS

Computer Networks/Networks

Notes The OSI model has both connection-oriented and connectionless communication in the
network layer and connection-oriented communication in the transport layer. The TCP/
IP model supports connectionless mode in the Internet layer and both modes in the transport
layer.

Self Assessment

Fill in the blanks:
6. The TCP/IP ……………………. layer corresponds to the network layer of the OSI reference
model in functionality.
7. TCP is a …………………………………. protocol and UDP is an unreliable connectionless
protocol.
8. OSI reference model divides the required functions of the ………………….. into several
layers and defines the function of each layer.
9. ………………….. are entities in the same layer on different computers.
10. ……………………. is the point from where services can be accessed.

2.5 Summary

The three basic components namely; hardware, protocols (software) and applications
(useful software) are mandatory to implement a computer network. It is also explained
that the concept of layers is important in networking.

Each layer with two layers works as the interface and protects the upper layer that each
one layer can change with minimum impact on the upper layers. In some cases, this
protection is so proficient that an application may not know that it is running on different
hardware.

The OSI network model has seven layers.
TCP/IP stands for Transmission Control Protocol/Internet Protocol. It was developed
with the objective to specify a suite of protocols capable of providing transparent
communications interoperability services between computers of all sizes, regardless of
the hardware or operating system platforms supporting them.

Over the years, TCP/IP has become the most widespread of today’s protocols. One reason
for TCP/IP’s popularity is the public availability of its protocols’ specifications. In this
sense, TCP/IP can justifiably be considered an open system. Most users rely on TCP/IP for
the purpose of file transfers, electronic-mail (e-mail), and remote login services.

2.6 Keywords

Internet Protocol: The Internet protocol suite is the set of communications protocols used for
the Internet and other similar networks.
Open Systems Interconnection (OSI) Reference Model: The International Standardization
Organization (ISO) developed the OSI model of data communications in 1984. OSI specifies a
seven-layer model that is used by the industry as the frame of reference when describing protocol
architectures and functional characteristics.

TCP/IP: Transmission Control Protocol (TCP) and Internet Protocol (IP) are two distinct network
protocols, technically speaking. TCP and IP are so commonly used together; however, that
TCP/IP has become standard terminology to refer to either or both of the protocols.

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