Network Topolgy Types

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Network Topologies
• LANs and WANs - Geographical coverage • LANs
– A single geographical location, such as office building, school, etc – Typically High speed and cheaper.

• WANs
– Spans more than one geographical location often connecting separated LANs – Slower – Costly hardware, routers, dedicated leased lines and complicated implementation procedures.

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Network Topologies
• Topology - Physical and logical network layout
– Physical – actual layout of the computer cables and other network devices – Logical – the way in which the network appears to the devices that use it.

• Common topologies:
– Bus, ring, star, mesh and wireless
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Bus topology
• Uses a trunk or backbone to which all of the computers on the network connect. • Systems connect to this backbone using T connectors or taps. • Coaxial cablings ( 10Base-2, 10Base5) were popular options years ago.

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Bus Topology
Advantages
Cheap and easy to implement

Disadvantages
Network disruption when computers are added or removed A break in the cable will prevent all systems from accessing the network. Difficult to troubleshoot.

Require less cable

Does not use any specialized network equipment.

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Ring Topology
• Logical ring
– Meaning that data travels in circular fashion from one computer to another on the network. – Typically FDDI, SONET or Token Ring technology are used to implement a ring network – Ring networks are most commonly wired in a star configuration • Token Ring has multi-station access unit (MSAU),equivalent to hub or switch. MSAU performs the token circulation internally. 5

Ring Topology

Advantages
Cable faults are easily located, making troubleshooting easier Ring networks are moderately easy to install

Disadvantages
Expansion to the network can cause network disruption A single break in the cable can disrupt the entire network. 6

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Star Topology
• All computers/devices connect to a central device called hub or switch. • Each device requires a single cable • point-to-point connection between the device and hub. • Most widely implemented • Hub is the single point of failure 7

Star Topology
Advantages
Easily expanded without disruption to the network Cable failure affects only a single user Easy to troubleshoot and isolate problems

Disadvantages
Requires more cable

A central connecting device allows for a single point of failure More difficult to implement

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Mesh Topology
• Each computer connects to every other. • High level of redundancy. • Rarely used. – – – – Wiring is very complicated Cabling cost is high Troubleshooting a failed cable is tricky A variation hybrid mesh – create point to point connection between specific network devices, often seen in WAN implementation. 9

Mesh Topology

Advantages
Provides redundant paths between devices The network can be expanded without disruption to current uses

Disadvantages
Requires more cable than the other LAN topologies Complicated implementation

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Wireless networking
• Do not require physical cabling • Particularly useful for remote access for laptop users • Eliminate cable faults and cable breaks. • Signal interference and security issue.

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Wireless networking

Advantages
Allows for wireless remote access Network can be expanded without disruption to current users

Disadvantages
Potential security issues associated with wireless transmissions Limited speed in comparison to other network topologies 12

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IEEE and Networking standards
• Institute of Electrical and Electronic Engineers (IEEE) developed a series of networking standards – Networking technologies developed by manufacturers are Compatible – Cabling, networking devices and protocols are all interchangeable under the banner of a specific IEEE 13

Specification Name
802.1 802.2 802.3 802.4 802.5 802.6 802.7 802.8 802.9 802.10 802.11 802.12 Internetworking The LLC(Logincal Link Control) sublayer CSMA/CD (...
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