1. Chapter 2: Basic Concepts
Line Configuration
Topology
Transmission Mode
Categories of Networks
Internetworks
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CS433 - Data Communications and Computer Networks

2. CS433 - Data Communications and Computer Networks
Line Configuration
Line configuration defines the attachment of communication devices to a link
Line Configuration
Point-to-point
Multi-point
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CS433 - Data Communications and Computer Networks

3. Point-to-Point Line Configuration
Provides a dedicated link between two devices
The entire capacity of the channel is reserved for transmission
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CS433 - Data Communications and Computer Networks

4. Point-to-Point Line Configuration
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CS433 - Data Communications and Computer Networks

5. Point-to-Point Line Configuration
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CS433 - Data Communications and Computer Networks

6. Multipoint or Multi-Drop Line Configuration
More than two devices share a single link
The capacity of the channel is shared either spatially or temporally
Spatial sharing: devices can use the link simultaneously
Temporal (time) sharing: devices take turns
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CS433 - Data Communications and Computer Networks

7. Multipoint Line Configuration
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CS433 - Data Communications and Computer Networks

8. CS433 - Data Communications and Computer Networks
Network Topology
Network Topology: defines the physical or logical arrangement of links in a network
The relative status of devices to be linked determines a topology. Two relationships are available:
Peer-to-Peer transmission: devices share the link equally
Primary-Secondary: one device controls traffic and the others must transmit through it
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CS433 - Data Communications and Computer Networks

9. CS433 - Data Communications and Computer Networks
Topology
Mesh
Star
Tree
Bus
Ring
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CS433 - Data Communications and Computer Networks

10. CS433 - Data Communications and Computer Networks
Mesh Topology
Every device has a dedicated point-to-Point link to every other device.
Fully connected mesh has n(n-1)/2 physical channels to link n devices.
Every device must have n-1 I/O ports.
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CS433 - Data Communications and Computer Networks

11. CS433 - Data Communications and Computer Networks
Mesh Topology
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CS433 - Data Communications and Computer Networks

12. CS433 - Data Communications and Computer Networks
Advantages
Each connection can carry its data load
Robust
Privacy or Security
Simple fault identification and isolation
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CS433 - Data Communications and Computer Networks

13. CS433 - Data Communications and Computer Networks
Disadvantages
Huge amount of cabling and I/O ports
Difficult to install and reconfigure
Space problem
The hardware required for connectors is expensive
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CS433 - Data Communications and Computer Networks

14. CS433 - Data Communications and Computer Networks
Star Topology
Each device has a dedicated point-to-point link only to a central controller (Hub)
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CS433 - Data Communications and Computer Networks

15. CS433 - Data Communications and Computer Networks
Advantages
Each device needs only one link and one I/O port
Easy to install and reconfigure
Small amount of cabling
Robust
Easy fault identification and isolation
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CS433 - Data Communications and Computer Networks

16. CS433 - Data Communications and Computer Networks
Disadvantages
The hub is the bottleneck
The hub is a single-point-of-failure
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CS433 - Data Communications and Computer Networks

17. CS433 - Data Communications and Computer Networks
Tree Topology
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CS433 - Data Communications and Computer Networks

18. CS433 - Data Communications and Computer Networks
Hubs
Active hub: contains a device that regenerates the received bit patterns before sending them out (Repeater)
Passive hub: Provides a simple physical connection between the attached devices
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CS433 - Data Communications and Computer Networks

19. CS433 - Data Communications and Computer Networks
Hubs (Cont’d)
Repeating strengthens transmission and increases the distance a signal can travel between sender and receiver
The central hub in the tree is an active hub
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CS433 - Data Communications and Computer Networks

20. CS433 - Data Communications and Computer Networks
Advantages
Tree Topology has the same advantages as those of a star.
Moreover,
More devices can be attached to a single central hub using secondary hubs
It increases the distance a signal can travel between devices
It provides a mechanism to prioritize and isolate communications
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CS433 - Data Communications and Computer Networks

21. CS433 - Data Communications and Computer Networks
Bus Topology
All devices are attached to one long cable (backbone)
Nodes are connected to the bus by drop lines and taps
Drop line: a cable running from the device to the bus
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CS433 - Data Communications and Computer Networks

22. CS433 - Data Communications and Computer Networks
Bus Topology (Cont’d)
Tap: a connector that either splices into the cable or punctures the sheathing of a cable to create a contact with the metallic core
There is a limit on the number of taps a bus can support and on the distance between those taps
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CS433 - Data Communications and Computer Networks

23. CS433 - Data Communications and Computer Networks
Bus Topology
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CS433 - Data Communications and Computer Networks

24. CS433 - Data Communications and Computer Networks
Advantages
Ease of installation
Less cabling than mesh, star, or tree
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CS433 - Data Communications and Computer Networks

25. CS433 - Data Communications and Computer Networks
Disadvantages
Difficult reconfiguration and fault isolation
Signal reflection at the taps can cause degradation
The bus is a single point-of-failure
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CS433 - Data Communications and Computer Networks

26. CS433 - Data Communications and Computer Networks
Ring Topology
Each device has a dedicated point-to-point line configuration only with the two devices on either side of it
Unidirectional traffic
Each device incorporates a repeater
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CS433 - Data Communications and Computer Networks

27. Ring Topology (Cont’d)
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CS433 - Data Communications and Computer Networks

28. CS433 - Data Communications and Computer Networks
Advantages
Easy to install and reconfigure
Simple fault isolation
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CS433 - Data Communications and Computer Networks

29. CS433 - Data Communications and Computer Networks
Disadvantages
Unidirectional traffic
The ring is a single point-of-failure
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CS433 - Data Communications and Computer Networks

30. CS433 - Data Communications and Computer Networks
Hybrid Topology
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CS433 - Data Communications and Computer Networks