This document discusses different types of computer networks. It defines peer-to-peer and client-server networks, describing their advantages and disadvantages. Peer-to-peer networks have no centralized control and are best for small networks with 10 or fewer users where security is not critical. Client-server networks have centralized control through servers and are better for larger networks that require sharing of resources and enhanced security. The document also covers network topologies like bus, star, ring and mesh, and network hardware such as switches, routers, hubs and bridges.

2.  Network Definition
 Types of Networks
 Fundamental Network Classifications
 Network Topology
 Types of Topology
 Advantages and Disadvantages of Network Topology
 Network hardware and software

3. ∙ The purpose of a network is to share resources.
∙ A network can be defined as two or more computers connected together in such a
way that they can share resources.
A sharable resource may be:
∙ A file
∙ A folder
∙ A disk drive
∙ Or just about anything else that exists on a computer.

4. Peer to peer network
∙ No centralized control
∙ Act as both client & server
∙ User controls access to machine
∙ Institutionalized chaos & security concerns
∙ Adding machines slows network down

5. Peer to Peer Advantages:
∙ Low cost
∙ Simple to configure
∙ User has full accessibility of the computer
∙ No Network Administrator
Peer to Peer Disadvantages:
∙ Security for only a single resource at a time
∙ Users may need to know many passwords
∙ Individual machine backups
∙ Decreases while sharing
∙ No central location/access of data

6. Where peer-to-peer network is appropriate:
∙ 10 or less users
∙ No specialized services required
∙ Security is not an issue
Peer to Peer Network

7. Client/Server Networking
∙ Server is the key to this type
∙ Centralized control of resources
∙ Utilize faster processors
∙ More memory
∙ Extra peripherals

8. Client/Server Networking
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

9. Client-Server Networking

10. Local Area Network (LAN)
∙ covering a small geographic are
∙ A room, a floor, a building
∙ Limited by no. of computers and distance covered
∙ Usually one kind of technology throughout the LAN
∙ Serve a department within an organization
Examples:
∙ Network inside the Student Computer Room
∙ Network inside your home

11. Client
Client
Client
Client Client
Client
The Local Area Network (LAN)

12. Metropolitan Area Network (MAN)
A Metropolitan Area Network (MAN) is a network that interconnects users with
computer resources in a geographic area or region larger than that covered by
even a large local area network (LAN) but smaller than the area covered by a
wide area network (WAN). It may interconnect of networks in a city or several
local area networks or sometimes referred to as a campus network.

13. Metropolitan Area Network (MAN)

14. Wide Area Network (WAN)
∙ WAN is a computer network that covers a broad area (i.e., any network whose
communications links cross metropolitan, regional, or national boundaries). Or, less
formally, a network that uses routers and public communications links
∙ The largest and most well-known example of a WAN is the Internet.
∙ WAN is are used to connect LANs and other types of networks together, so that
users and computers in one location can communicate with users and computers in
other locations

15. Wide Area Network (WAN)

16.  A topology is a way of “laying out” the network. Topologies can be either physical or
logical.
 Physical topologies describe how the cables are run.
 Logical topologies describe how the network messages travel
Types Topology -
∙ Bus (can be both logical and physical)
∙ Star (physical only)
∙ Ring (can be both logical and physical)
∙ Mesh (can be both logical and physical)

17. Bus Topology:
A bus is the simplest physical topology. It consists of a single cable that runs to
every workstation Commonly referred to as a linear bus, all the devices on a bus
topology are connected by one single cable.
∙ Simple and low-cost
∙ A single cable called a trunk (backbone, segment)
∙ Only one computer can send messages at a time
∙ Passive topology - computer only listen for, not regenerate data
Bus Topology

18. Star Topology:
∙ A physical star topology branches each network device off a central device called
a hub, making it very easy to add a new workstation.
∙ The star topology is the most commonly used architecture in Ethernet LANs.
∙ Star topologies are easy to install. A cable is run from each workstation to the hub.
The hub is placed in a central location in the office.
∙ Star topologies are more expensive to install than bus networks, because there
are several more cables that need to be installed, plus the cost of the hubs that are
needed.

19. Ring Topology:
∙ Each computer connects to two other computers, joining them in a circle creating
a unidirectional path where messages move workstation to workstation.
∙ Each entity participating in the ring reads a message, then regenerates it and
hands it to its neighbor on a different network cable.
∙ The ring makes it difficult to add new computers.
Ring Topology

20. 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.
Mesh Topology

21. Topology Advantages Disadvantages
Bus Cheap. Easy to install Difficult to reconfigure.
Break in bus disables
entire network.
Star Cheap. Easy to install.
Easy to reconfigure.
Fault tolerant.
More expensive than bus.
Ring Efficient. Easy to install. Reconfiguration difficult.
Very expensive
Mesh Simplest. Most fault tolerant Reconfiguration extremely difficult.
Extremely expensive.
Very complex.

22.  Network Interface Card (NIC)
 Repeater
 Hub
 Bridge
 Routers
 Switch

23. Network Interface Card (NIC)
∙ NIC provides the physical interface between computer and cabling. It
prepares data, sends data, and controls the flow of data. It can also receive and
translate data into bytes for the CPU to understand.
Repeater
∙ A network device used to regenerate or replicate a signal. Repeaters are used
in transmission systems to regenerate analog or digital signals distorted by
transmission loss. Analog repeaters frequently can only amplify the signal while digital
repeaters can reconstruct a signal to near its original quality.
Hub
∙ Hub is a common connection point for devices in a network. Hubs are
commonly used to connect segments of a LAN. A hub contains multiple ports. When
a packet arrives at one port, it is copied to the other ports so that all segments of the
LAN can see all packets.

24. Bridge
∙ Bridge join similar topologies and are used to divide network segment. It
device that connects two local-area networks (LANs), or two segments of the same
LAN that use the same protocol, such as Ethernet or Token-Ring.
Routers
∙ A router is a device that forwards data packets along networks. A router is
connected to at least two networks, commonly two LANs or WANs or a LAN and
its ISP's network. Routers are located at gateways, the places where two or more
networks connect.
Switch
∙ In network, a device that filters and forwards packets between LAN segments.
Switches operate at the data link layer (layer 2) and sometimes the network layer
(layer 3) of the OSI Reference Model and therefore support any packet protocol. LANs
that use switches to join segments are called switched LANs or, in the case of Ethernet
networks, switched Ethernet LANs.