LANs

WANs

Network Models

• Peer-to-peer Networking Model– A peer-to-peer network is a decentralized network model offering

no centralized storage of data or centralized control over the sharing of files or resources. All systems on a peer-to-peer network can share the resources on their local computer as well as use resources of other systems.

• Client/Server Networking Model– The client/server networking model is, without question, the most

widely implemented model and the one you are most likely to encounter when working in real-world environments. The advantages of the client/server system stem from the fact that it is a centralized model. It allows for centralized network management of all network services, including user management, security, and backup procedures.

Comparison of Networking Models

Attribute Peer-to-Peer Network Client/Server Network

Size Restricted to a maximum of 10 computers.

The size of the network is limited only by server size and network hardware, and it can have thousands of connected systems.

Administration Each individual is responsible for the administration of his or her own system. A administrator is not needed.

A skilled network administrator is often required to maintain and manage the network.

Security Each individual is responsible for maintaining security for shared files or resources connected to the system.

Security is managed from a central location but often requires a skilled administrator to correctly configure.

Cost Minimal startup and implementation cost.

Requires dedicated equipment and specialized hardware and administration, increasing the cost of the network.

Network Topologies

• A topology refers to both the physical and logical layout of a network. The physical topology of a network refers to the actual layout of the computer cables and other network devices. The logical topology of a network, on the other hand, refers to the way in which the network appears to the devices that use it.

Bus Topology

Advantages Disadvantages

Compared to other topologies, a bus is cheap and easy to implement.

There might be network disruption when computers are added or removed.

Requires less cable than other topologies. Because all systems on the network connect to a single backbone, a break in the cable will prevent all systems from accessing the network.

Does not use any specialized network equipment.

Difficult to troubleshoot.

A bus network uses a trunk or backbone to which all of the computers on the network connect.

Ring Topology

Advantages Disadvantages

Cable faults are easily located, making troubleshooting easier.

Expansion to the network can cause network disruption.

Ring networks are moderately easy to install.

A single break in the cable can disrupt the entire network.

The ring topology is actually a logical ring, meaning that the data travels in circular fashion from one computer to another on the network.

Star Topology

Advantages DisadvantagesStar networks are easily expanded without disruption to the network.

Requires more cable than most of the other topologies.

Cable failure affects only a single user. A central connecting device allows for a single point of failure.

Easy to troubleshoot and isolate problems. More difficult than other topologies to implement.

In the star topology, all computers and other network devices connect to a central device called a hub or switch.

Mesh Topology

Advantage Disadvantage

Provides redundant paths between devices

Requires more cable than the other LAN topologies.

The network can be expanded without disruption to current users.

Complicated implementation.

The mesh topology incorporates a unique network design in which each computer on the network connects to every other, creating a point-to-point connection between every device on the network.

Specification Name

802.1 Internetworking

802.2 The LLC (Logical Link Control) sub layer

802.3 CSMA/CD (Carrier Sense Multiple Access with Collision Detection) for Ethernet networks

802.4 A token passing bus

802.5 Token Ring networks

802.6 Metropolitan Area Network (MAN)

802.7 Broadband Technical Advisory Group

802.8 Fiber-Optic Technical Advisory Group

802.9 Integrated Voice and Data Networks

802.10 Standards for Interoperable LAN/MAN Security (SILS) (Network Security)

802.11 Wireless networks

802.12 100Mbps technologies, including 100BASEVG-AnyLAN

IEEE and Networking StandardsThe Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standards to ensure that networking technologies developed by respective manufacturers are compatible.