OSI Reference Model:-

TCP/IP and OSI
Modal



OSI Reference Model
:
-

The seven layers of the OSI model are as follows:



Physical layer:

Converts the data into the stream of electric or analog pulses that will
actually cross the transmission medium and oversees the transmission of the data



Data Link
layer:

Provides an interface with the network adapter; maintains logical
links for the subnet



Network layer:

Supports logical addressing and routing



Transport layer:

Provides error control and flow control for the internetwork



Session layer:

Establishes se
ssions between communicating applications on the
communicating computers



Presentation layer:

Translates data to a standard format; manages encryption and
data compression



Application layer:

Provides a network interface for applications; supports network
ap
plications for file transfer, communications, and so forth



TCP/IP Protocol Architecture

TCP/IP protocols map to a four
-
layer conceptual model. The four layers
of

model are:
Application, Transport, Internet, and Network Interface. Each layer
in

model cor
responds to
one or more layers of the seven
-
layer Open Systems Interconnection (OSI) model.

TCP/IP and OSI
Modal



The APRANET initially started with four Internet message processors (IMPs), located at the
UCLA, UCSA, Stanford research institute and the University of Utah. In
the early years, the
purpose and usage of the APRANET network was widely discussed, leading to many
enhancements and modifications as the users steady increased and requested demanded more
from the network. As time passed many enhancements were made to the

existing protocol but
by 1973 it was clear that NCP (Network Control Protocol) was unable to handle the volume
of traffic passing through it network and proposed a new functionality. A new protocol
TCP/IP Transmission Control Protocol / Internet Protocol
was developed over time to replace
NCP.









TCP/IP and OSI
Modal



Difference between TCP/IP and OSI Model


TCP/IP modal


OSI modal

1. The TCP/IP model doesn’t clearly
摩sti湧畩sh 扥tween serviceⰠinterval an搠
灲潴潣潬.

ㄮ⁔he lSI潤ol
潲iginally 摩sti湧畩shes
扥tween serviceⰠ interval an搠灲潴潣潬s.

㈮⁔he TCm/Im m潤ol is an im灬ementation 潦
the lSI m潤ol.

㈮⁔he lSI潤ol is a⁲eference m潤ol.

㌮⁉n TCm/Tm m潤olⰠthe 灲潴潣潬s came firstⰠ
an搠the m潤ol was really just a⁤ scri灴i潮
潦
the existi湧 灲潴潣潬s.

㌮⁉n lSI潤olⰠthe 灲潴潣潬s came after the
m潤ol was 摥scri扥搮

㐮⁉n TCm/Im m潤ol ⰠIhe 灲潴潣潬s are潴
hi摤dn.

㐮⁉n lSI潤olⰠthe 灲潴潣潬s are 扥tter
hi摤dn.

㔮⁔he TCm/Im m潤ol has 潮ly 㐠4ayers.

㔮⁔he lSI潤ol has

㜠Tayers.

㘮⁔he TCm/Im m潤ol su灰潲ts 扯bh
c潮necti潮oess an搠c潮nection
-
潲iente搠
c潭mu湩cation in the trans灯pt layer⸠givi湧
users the ch潩ce.

㘮⁔he lSI潤ol su灰潲ts 扯bh
c潮necti潮oess an搠c潮nection
-
潲iente搠
c潭mu湩cation in the netw潲欠layerⰠ
扵t 潮ly
c潮necti潮
-
潲iente搠c潭mu湩cation in
trans灯pt layer.




Reference



Where Wizards Stay Up Late
-

Katie Hafner and Matthew Lyons

Inside the PC
-

Peter Norton