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Chapter 1
Introduction
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Networks
Network
- the interconnection of a set of devices capable
of communication.
Device
- can be a host such as a large computer, desktop,
laptop, workstation, cellular phone, or security
system.
- can also be a connecting device such as a router a
switch, a modem that changes the form of data, and
so on.
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Networks (Continued)
Local Area Networks
Point-to-Point WANs
Switched WANs
Wide Area Networks
Internetwork
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An Isolated LAN in the past and today
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A Point-to-Point WAN
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A Switched WAN
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An internetwork made of two LANs and one WAN
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A heterogeneous network made of WANs and LANs
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Switching
- connects at least two links together.
- needs to forward data from a link to another link
when required.
Circuit-Switched Network
Packet-Switched Network
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A circuit-switched network
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A packet-switched network
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The Internet
- The most notable internet
- is composed of thousands of inter-connected
networks.
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The Internet today
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PROTOCOL LAYERING
- A protocol defines the rules that both the
sender and receiver and all intermediate
devices need to follow to be able to
communicate effectively.
- When communication is simple, we may
need only one simple protocol
- when the communication is complex, we
need a protocol at each layer, or protocol
layering.
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A single-layer protocol
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A three-layer protocol
Postal carrier facility
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Logical connection between peer layers
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TCP/IP Protocol Suite
- used in the Internet today
- It is a hierarchical protocol made up of interactive
modules, each of which provides a specific
functionality
- The term hierarchical means that each upper level
protocol is supported by the services provided by one
or more lower level protocols
- is thought of as a five-layer model
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TCP/IP Protocol Suite (continued)
Layered Architecture
Layered in the Suite
Description of Each Layer
Application Layer
Transport Layer
Network Layer
Data-link Layer
Physical Layer
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TCP/IP Protocol Suite (continued)
Encapsulation and Decapsulation
Addressing
Multiplexing and Demultiplexing
Encapsulation at the Source Host
Decapsulation and Encapsulation at Router
Decapsulation at the Destination Host
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Communication through an internet
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Logical connections between layers in TCP/IP
Logical connections
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Identical objects in the TCP/IP protocol suite
Identical objects (messages)
Identical objects (segment or user datagram)
Identical objects (datagram)
Identical objects (frame)
Identical objects (bits)
Identical objects (datagram)
Identical objects (frame)
Identical objects (bits)
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Encapsulation / Decapsulation
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Addressing in the TCP/IP protocol suite
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Multiplexing and demultiplexing
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The OSI Model
- An ISO standard that covers all aspects of network
communications
- It was first introduced in the late 1970s
OSI versus TCP/IP
Lack of OSI Model’s Success
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The OSI model
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TCP/IP and OSI model
