Network Topologies

Physical topologies describe how the cables are run in the network

A topology is a way of laying out the network

Physical Topologies

Bus Star Ring Mesh Hybrid

Logical Technology

Logical technology describe how the data or network messages travelEthernetToken RingFDDI

Bus Topology

In the bus topology, the network nodes (computers, printers, and other devices connected together to share information) are connected to a common backbone cable

Bus Topology

Data is sent to all computers on the trunk. Each computer examines EVERY packet on the wire to determine who the packet is for and accepts only messages addressed to them.good for a temporary, small (fewer than 10 people) networkPerformance degrades as more computers are added to the bus Bus is a passive topology .

Advantages of Bus Topology

Works well for small networks Inexpensive to implement on a small scale Requires less cable Easy to add another workstation

Disadvantages of Bus Topology

Management costs often too high Difficult to isolate a malfunctioning node or cable segment and associated connectors Possible for defective node to take down the entire network Subject to congestion from network traffic

Star Topology

The star topology is a network configured with a central hub and individual cable segments connected to the hub, resembling the shape of a star. A hub is a central device used in the star topology that joins single cable segments or individual LANs into one network.

Star Topology

Hub

Advantages of Star Topology

Easier to manage than a bus Easier to locate node and cable problems Easier to expand than a bus or ring, especially for enterprise networking Well suited for expansion into high-speed networking More equipment options

Disadvantages of Star Topology

Susceptible to a single point of failure Requires more network cable at the start than a bus

Ring Topology

A ring topology is a network in the shape of a ring or circle, with nodes connected around the ring.

Ring Topology

Ring

Ring Topology (LAN)

Redundant ring to avoid network failure

Repeaters at each component Unidirectional transmission links Closed loopTypically used
in FDDI networks

Advantages of Ring Topology

Easier to manage than a bus Easier to locate node and cable problems Good over long distances Handles high-volume traffic well Very reliable

Disadvantages of Ring Topology

Requires more network cable and equipment at the start than a bus Not as many equipment options as for a bus Not as widely used as the bus topology

Hybrid (Bus-Star)

Hub

Hub

Mesh Environment

Every device interconnected Most expensive Most Fault tolerant Cable fault tolerant Device fault tolerant The Internet is Mesh Topology

Mesh Topology

Figure 2-9