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

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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

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

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

Multipoint Line Configuration Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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. Dr. Shawakfa CS433 - Data Communications and Computer Networks

CS433 - Data Communications and Computer Networks Mesh Topology Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

CS433 - Data Communications and Computer Networks Tree Topology Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

CS433 - Data Communications and Computer Networks Bus Topology Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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 Dr. Shawakfa CS433 - Data Communications and Computer Networks

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

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

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

CS433 - Data Communications and Computer Networks Hybrid Topology Dr. Shawakfa CS433 - Data Communications and Computer Networks