Topology
The geometric arrangement of the computers in a network.
Personal computer LANs
- Low cost
* Limited data rate
Back end networks
Interconnecting large systems (mainframes and large storage devices) • High data rate • High speed interface • Distributed access • Limited distance • Limited number of divices
Storage Area Network
- Separate network handling storage needs
- Detaches storage task from specific servers
- Shared storage facility across high-speed network
- Hard disks, tape libraries, CD arrays
- Improved client-server storage access
- Direct storage to storage communication for backup
High speed office networks
- Desktop image processing
* High capacity local storage
Backbone LANs
- Part of network infrastructure that connect various piece of network.
- Interconnect low speed local LANs
- Reliability
- Capacity
- Cost
Bus Network
- The ends are not connected
- All communications are carried on a common cable or bus and are available to each device on the network.
- Maintained by contention
Contention
If a line is unused, a terminal or device can transmit its message at will, but if two or more terminals initiate messages simultaneously, they must stop and transmit again at different intervals.
Pros of Bus Network
- It has a single line to which all the network needs are attached
- Smaller size network
- The bur is simple, reliable in a small network
- It requires the least amount of calbe
Cons of Bus Network
- Heavy network traffic can stand a bus network since only one computer at a time can send a message.
- If there is a problem with the cable, the entire network breaks down.
Ring Network
• A circle or point-to-point connections of computers at dispersed locations, with no central host computer.
• All of the nodes are connected in a closed loop.
• Messages travel around the ring, with each node reading those messages addressed to it.
• Repeaters joined by point-to-point links in closed loop
- Revieve data on one link and retransmit on another
- Links unidirectional
- Stations attach to repeaters
• Data in frames
- Circulates past all stations
- Destination recognizes address and copies frame
- Frame circulates back to source where it is removed
- Only one station can transmit at a time
Pros of Ring Network
• A ring network links all nodes together in a circular chain.
• They can span larger distance than other types of networks because each nodes regenerates messages as they pass through it.
• Data/message travel in only ONE direction
- no one computer can monopolize the network
- It problem better than bus network.(data transfer rate)
Cons of Ring Network
- One faulty device can create network problems for the Ring network.
- Moves/add and changes of devices can affect network
- spam
Star Network
• Used to connect one or more small computers or peripheral devices to a large host computer or CPU.
• Each station connected directly to central node
- Usually via two-point-to point links
• Central node can be broadcast
- Physical star, logical bus
Pros of Star Network
- A star network has a central controller that is responsible for managing the network.
- All message are routed through the central controller(switch) which act as a traffic police to prevent network collisions
- Easy to install and extend
- Easy to disconnect faulty devices.
- Single computer failure does not necessarily bring down the entire network. (no disruption)
Cons of Star Network
• High dependence of the system: - On the functioning of the switch • Requires more cables - Compared to bus & ring topology • Once the central device (hub/switch) gets damaged: - The entire network becomes unusable
Mesh Topology
• Computers and network devices are:
- Interconnected with one another
• Allows most transmissions to be distributed
- Even if one of the connections go down
• Not commonly used
- Difficult and expensive to have redundant connection to every computer
Pros of Mesh Topology
• If one of the links or nodes fail:
- The connection is still available
• Most fault tolerant network topology
Cons of Mesh Topology
• Redundant cables make the topology:
- Difficult to setup - Expensive to lay the cables
Wireless Topology
• Does not use cabling but uses either: - Infrared light - Radio transmission • Infrared light: - Requires line of sight for nodes • Radio transmission: - Experiences difficulties caused by: ~ Building structures ~ Interference generated by other electrical equipment
Pros of Wireless Topology
• Save on costs of laying the cables • Users can move freely • Can handle larger amount of users - Compared to limited ports in a switch • Instant transfer of information to social media is made so much easier
Cons of Wireless Topology
- Normally slower
* Obstructed by obstacles
Hybrid Topology
• Combination of 2 or more different topologies
- Star, bus and ring topology are connected together
• Not just having characteristics of ONE specific topology
• Can be classified into two types:
- Hierarchical star
- Tree topology
Pros of Hybrid Topology
• Scalable
- Easy to increase the size of the network by adding new components without disturbing the existing networks
• Flexible:
- Can be designed according to the requirements of the organization
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Chapter 1 - Introduction to Computer Networks and Data Communications40
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Chapter 5 - Local Area Networks: Software and Support Systems23
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Chapter 4 - Conducted and Wireless Media24
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Chapter 3 - Network hardware devices39
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Chapter 2 – Basic concepts of Data and Signals16
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Chapter 6 - Internet Protocol18
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Chapter 7 - Network Topologies26
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Chapter 8 - Network Design and Management11
