The TCP/IP reference

inexpensivedetailedNetworking and Communications

Oct 23, 2013 (3 years and 7 months ago)

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Section 2.3

1

The TCP/IP reference
model


the de facto Internet standard


demonstrates arbitrary nature of
layers


various models are possible


OSI & TCP/IP are the two most
important

Section 2.3

2

The TCP/IP reference
model


Specifications for development:


information flows regardless of
the condition of the network


packets get to their destination
every time


packets can travel from any point
to any other point


TCP/IP resulted


DoD project


standard on which the Internet has
grown

Section 2.3

3

Layers of the TCP/IP
model


Four layers:


A
pplication


T
ransfer


I
nternet


N
etwork Access



IMPORTANT
--
even though the
names may be the same as the
OSI layers,
do not confuse the
layers of the two models.

The
layers include different
functions in each model.

Section 2.3

4

Application Layer


One application layer handles
all high
-
level protocols


Includes the functions of the OSI
Presentation & Session layers


Assumes data is properly
packaged for the next layer


Handles issues of
representation, encoding, and
dialog control

Section 2.3

5

Transport Layer


Quality of service


Reliability, flow control, error
correction


Uses TCP protocol


Transmission Control Protocol


Reliable, low
-
error


Packages application layer data
into segments

Section 2.3

6

Internet Layer


Sends source packets across the
internetwork independent of
path


Uses IP


Internet Protocol


Best Path determination


Packet Switching


Logical connection formed by
packets between hosts

Section 2.3

7

Network Access Layer


Also Host to Network layer


Deals with issues that an IP
packet requires to actually make
a physical link


Includes LAN & WAN
technology


Includes all the OSI physical
and data link layer details

Section 2.3

8

TCP/IP Protocols
--
Application Layer


Application layer protocols:


FTP: File Transfer Protocol


HTTP: Hypertext Transfer
Protocol


SMTP: Simple Mail Transport
Protocol


DNS: Domain Name Service


TFTP: Trivial File Transport
Protocol


Emphasizes flexibility for
software developers

Section 2.3

9

TCP/IP Protocols
--
Transport Layer


TCP: Transmission Control
Protocol


UDP: User Datagram Protocol

Section 2.3

10

TCP/IP Protocols
--
Internet Layer


Only one protocol


IP: Internet Protocol


Deliberate design


Any computer can communicate
at any time

Section 2.3

11

Comparing TCP/IP with
OSI

Section 2.3

12

Comparing TCP/IP with
OSI


Similarities


both have layers


both have application layers,
though they include very different
services


both have comparable transport
and network layers


packet switched (not circuit
switched) technology is assumed


networking professionals need to
know both

Section 2.3

13

Comparing TCP/IP with
OSI


Differences


TCP/IP combines the presentation
and session layer issues into the
application layer


TCP/IP combines the OSI data
link layer and physical layers into
one layer
--
the network access
layer


TCP/IP appears simpler because it
has fewer layers


TCP/IP protocols are the
standards around which the
Internet is built

Section 2.3

14

Conceptual nature of the
OSI model


No networks are built around
specific OSI protocols


Everyone uses the OSI model to
guide their thinking


You will use the OSI model, but
the TCP/IP protocols