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Network Topology. LAN (Local Area Network) A group of computers and associated devices (printers, etc.) connected through a wired or wireless medium by networking devices (hubs, switches, routers) u se protocols for communication. Review : Computer Network. Objectives. Topology
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Network Topology RD-CSY1017
LAN (Local Area Network) A group of computers and associated devices (printers, etc.) connected through a wired or wireless medium by networking devices (hubs, switches, routers) use protocolsfor communication Review : Computer Network RD-CSY1017
Objectives • Topology • Layout of how devices connect on network • Wired Networks • Wireless Networks RD-CSY1017
Connecting computers on Network - Link Access Two types of connections: • Dedicated or Point-to-point • Direct connection between two computers • Shared • Multiple computers share the media RD-CSY1017
Network Topologies • Topology: Physical layout of network. • Some of the popular network topologies are: • Star Topology • Distributed Star • Bus Topology • Ring Topology • Tree Topology • Mesh • Full Mesh • Partial Mesh RD-CSY1017
Advantages Each network connection is independent It can be customised to suit the type of data for example: data speed and technology It is easy to enforce security and privacy. Disadvantages Not scalable for large networks Point to Point network Dedicated Access - Point to Point connections Computer A Black links show four connections from computer A to all computers in the network RD-CSY1017
Star Topology Individual computers are connected to a central point – a hardware device, called a hub/switch . Max distance between a computer and hub/switch is restricted based on cable used. With UTP cable, distance limited to 100m. Popular topology for LAN (local area networks) Adv:Failure of any computer does not affect other communications in the network Disadv: Failure of hub/switch can bring the network down, also called SPF( Single Point of Failure) Star Topology Extended Star Topology RD-CSY1017
Tree Topology • Also called a "hierarchical" or "star of stars" topology • Nodes are connected in groups of star-configured workstations that branch out from a single "root," • The root node usually controls the network and sometimes network traffic flow. • This topology is easy to extend: when new users need to be added RD-CSY1017
Mesh Topology Full Mesh • Full mesh topology • each node is physically connected to every other node • Adv: Highly fault tolerant: when one node fails, traffic can easily be diverted to other nodes • Disadv: Not scalable for large networks • Partial mesh topologies are popular for backbone networks, where redundancy is desirable Partial Mesh RD-CSY1017
Computers are connected to each other to form a closed loop. Common Examples FDDI Network Usually Fibre optic cable based backbone networks Token Ring Network Example: IBM token ring network Proprietary network Adding and removing computers disrupts the network. What should be done to provide redundancy in a ring topology ? cable computer Ring Topology RD-CSY1017
Topologies relevant to Wireless Networks • Most wireless implementations are based on • Star, tree or line topology • Two modes: • Ad hoc • No need of central access point • Problem: Not scalable • Infrastructure (more common) • Central Access Point (AP) is needed • Scalable • Many wireless implementations are based on more than one topology RD-CSY1017
Wireless Topology- Infrastructure Star • Hotspots, Offices and WISP's • Point to Multipoint • The most common infrastructure in wireless networking point-2-point • Connecting two wireless clients directly • Building to building (when one has Internet connection and the other one does not) point-2-point - Repeating Necessary when direct line of sight (LOS) is obstructed RD-CSY1017
Wireless Networks – Mesh Topology • Mesh topologies are an interesting option mainly in • dynamic environments (urban areas) where central infrastructure is hard to implement • when redundancy is desired • Typical cases are: municipal networks, campus networks etc. RD-CSY1017
Wireless Cellular Technology • At the center of any cellular technology is the cellular transceiver, an omni-directional antenna whose range projects a circular "footprint." This footprint is the "cell" that gives cellular technology its name • As the cellular user moves from one cell to another, the user's signal is transferred from one antenna to another RD-CSY1017
Factors influencing choice of topology? ? ? ? ? RD-CSY1017
What is the role of network card? RD-CSY1017
Task: • Use packet tracer to set up a network using following Topologies • Star • Distributed Star • Point-to-point • Tree • Refer to your task sheet for details RD-CSY1017