1. Categories of Networks
Computer Networks
Al-Mustansiryah University
Elec. Eng. Department College of Engineering Fourth Year Class
Lec 3
Categories of Networks
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2. Categories of Networks
Local Area Networks (LANs)
Short distances
Designed to provide local interconnectivity
Wide Area Networks (WANs)
Long distances
Provide connectivity over large areas
Metropolitan Area Networks (MANs)
Provide connectivity over areas such as a city, a campus
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3. Figure 1.10 An isolated LAN connecting 12 computers to a hub in a closet
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4. Figure 1.11 WANs: a switched WAN and a point-to-point WAN
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5. 1-4 PROTOCOLS
A protocol is synonymous with rule. It consists of a set of rules that govern data communications. It determines what is communicated, how it is communicated and when it is communicated. The key elements of a protocol are syntax, semantics and timing
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6. Peer-to-Peer Networks
Peer-to-peer network is also called workgroup
No hierarchy among computers  all are equal
No administrator responsible for the network
Peer-to-peer

7. Advantages of peer-to-peer networks:
Low cost
Simple to configure
User has full accessibility of the computer
Disadvantages of peer-to-peer networks:
May have duplication in resources
Difficult to uphold security policy
Where peer-to-peer network is appropriate:
10 or less users
No specialized services required
Security is not an issue

8. Clients and Servers Network Clients (Workstation)
Computers that request network resources or services
Network Servers
Computers that manage and provide network resources and services to clients
Usually have more processing power, memory and hard disk space than clients
Run Network Operating System that can manage not only data, but also users, groups, security, and applications on the network.

9. Advantages of client/server networks
Facilitate resource sharing – centrally administrate and control
Facilitate system backup and improve fault tolerance
Enhance security – only administrator can have access to Server
Support more users – difficult to achieve with peer-to-peer networks
Disadvantages of client/server networks
High cost for Servers
Need expert to configure the network
Introduce a single point of failure to the system