ch01
DESCRIPTION
TRANSCRIPT
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Introduction
• Data Communication
• Networks
• Protocols and Standards
• Standard Organizations
• Basic Concepts
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Computer Networks
Computer network connects two or more autonomous computers.
Introdution to Computer Networks
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Applications of Networks
Introduction to Computer Networks
Resource SharingHardware (computing resources, disks, printers)Software (application software)
Information SharingEasy accessibility from anywhere (files, databases)Search Capability (WWW)
CommunicationEmailMessage broadcast
Remote computing
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Data Communication System Components
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Basic Concepts
• Line Configuration• Topology• Transmission Mode• Categories of Networks• Internetworks
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Point-to-Point Line Configuration
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Point-to-Point Line Configuration
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Point-to-Point Line Configuration
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Multipoint Line Configuration
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Simplex
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Half-Duplex
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Full-Duplex
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LAN, MAN & WAN
Network in small geographical Area (Room, Building or a Campus) is called LAN (Local Area Network)
Network in a City is call MAN (Metropolitan Area Network)
Network spread geographically (Country or across Globe) is called WAN (Wide Area Network)
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Local Area Network
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Local Area Network
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Metropolitan Area Network
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Wide Area Network
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Figure 2-19
WCB/McGraw-Hill The McGraw-Hill Companies, Inc., 1998
Internetwork (Internet)
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Network Topology
The network topology defines the way in which computers, printers, and other devices are connected. A network topology describes the layout of the wire and devices as well as the paths used by data transmissions.
Introduction to Comuter Networks
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Mesh Topology
The mesh topology connects all devices (nodes) to each other for redundancy and fault tolerance.
It is used in WANs to interconnect LANs and for mission critical networks like those used by banks and financial institutions.
Implementing the mesh topology is expensive and difficult.
Introduction to Computer Networks
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Mesh Topology
Merits
• No congestion problem
• No MAC protocols are needed
• More Secure
• It is Robust
• Fault identification is easy
Demerits
• Cable length
• Impractical for large networks
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Star & Tree Topology
Itroduction to Computer Networks
The star topology is the most commonly used architecture in Ethernet LANs.
When installed, the star topology resembles spokes in a bicycle wheel.
Larger networks use the extended star topology also called tree topology. When used with network devices that filter frames or packets, like bridges, switches, and routers, this topology significantly reduces the traffic on the wires by sending packets only to the wires of the destination host.
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Star & Tree Topology
Merits
• Cheaper than Mesh Topology
• Relatively easier to install, maitain & configure
Demerits
• If hub goes down the entire network becomes defunct
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Ring Topology
Introduction to Computer Networks
A frame travels around the ring, stopping at each node. If a node wants to transmit data, it adds the data as well as the destination address to the frame.
The frame then continues around the ring until it finds the destination node, which takes the data out of the frame.
Single ring – All the devices on the network share a single cable
Dual ring – The dual ring topology allows data to be sent in both directions.
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Ring topology
Merits
• Easy to reconfigure and install.
• Fault isolation is relatively easy in a ring.
Demerits
• If a node in a simple ring fails, the whole ring can not function.
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Bus Topology
Commonly referred to as a linear bus, all the devices on a bus topology are connected by one single cable.
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Bus Topology
Merits
• Easy to install
• Uses less cable
Demerits
• Relatively difficult to add new nodes.
• Even if a portion of the bus breaks down, the whole bus can not function.