Network Topologies

Lecturer: Hyder R. Hamandi

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 Bus

StarStar

RingRing

Mesh Mesh

HybridHybrid

Logical Technology

Logical technology describe how the data or network messages travelEthernetToken RingFDDI

Bus TopologyBus 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 TopologyBus 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) network

•Performance degrades as more computers are added to the bus

• Bus is a passive topology .

Advantages of Bus TopologyAdvantages 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 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 TopologyStar 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 TopologyStar Topology

Hub

Advantages of Star TopologyAdvantages 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 TopologyDisadvantages of Star Topology

Susceptible to a single point of failure

Requires more network cable at the start than a bus

Ring TopologyRing Topology

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

Ring TopologyRing Topology

Ring

Ring Topology (LAN)Ring Topology (LAN)

Redundant ring to avoid network failure

• Repeaters at each component

• Unidirectional transmission links

• Closed loop

• Typically used in FDDI networks

Advantages of Ring Advantages of Ring TopologyTopologyAdvantages of Ring Advantages of Ring TopologyTopology

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 TopologyDisadvantages of Ring TopologyDisadvantages of Ring TopologyDisadvantages 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)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