Topology munsifullah daudzaikhurasan university
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The document discusses different network topologies including mesh, star, tree, bus, and ring. It defines topology as the geometric representation of links and nodes in a network. Each topology is described in terms of its structure, advantages, and disadvantages. Mesh topology uses dedicated point-to-point links between all devices but requires many links and ports. Star topology uses dedicated links from each device to a central hub, requiring less cabling than mesh. Tree topology extends star topology with secondary hubs connected to a central hub. Bus topology uses a backbone with drop lines to connect devices. Ring topology passes signals in one direction around a loop between devices.
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Topology munsifullah daudzaikhurasan university
- 1. TOPOLOGY The Topology is the geometric representation of the relationship of the links and the linking devices (Nodes) in a Network Or Topology defines the physical or the Logical Agreement of Links in a Network Topology of a Network is suggestive of how a network is laid out. It refers to the specific configuration and structure of the connections between the Links and the Nodes. Two or more devices connect to a Link and two or more Links form a Topology Categories of TOPOLOGY Every device has dedicated a point-to-point link to every other device Dedicated: Means that the link carries traffic only between these two devices n(n-1)/2 Links to connect n devices
- 2. Each device must have n-1 I/O Ports Example Mesh Topology In figure above, we have 5 Nodes, therefore: No. of Links= 5(5-1)/2 = 10 No. of I/O Ports= 5-1 = 4 This increase exponentially with increase in No. of Nodes e.g. for 6 nodes = 15 Links 7 Nodes=21 Links Advantages of Mesh Topology Use of Dedicated links guarantees that each connection can carry its own load. This eliminates Traffic Problems as in case of Shared Link Mesh Topology is robust. If one link fails, it does not effect other links Security & Privacy due to dedicated links Point to Point links make Fault Identification easy Disadvantages of Mesh Topology Amount of Cabling makes Installation & Reconfiguration difficult bulk of wiring can be greater than the available space Number of I/O Ports Required to connect each link can be expensive Each device has a dedicated point-to-point link to a central controller (Hub/Switch) Devices are not directly connected to each other Controller (Hub/Switch) acts as an exchange If one device wants to send data to the other, it sends the data to the controller, which then retransmits it to the other connected device
- 3. Advantages of Star Topology Less Cabling Less Expensive than Mesh as each device needs only one link and one I/O Port Easy to Install and Reconfigure Robust, if a link fails , only that link fails Easy Fault Detection Disadvantages of Star Topology Although Cabling required is far less than Mesh still each node must be connected to a Hub , so Cabling is still much more than some other Topologies A variation of Star Topology Nodes in a Tree are linked to a central hub that controls the traffic to and from network Difference b/w star and tree is not all the devices plug directly in to the central HUB/SWITCH Majority connects to secondary hub that is connected to central hub in Tree Topology Central Hub in a Tree is an ACTIVE HUB ACTIVE HUB contains a repeater or other active Hub/Switch Repeater is a hardware device that regenerates the received bit pattern before sending them out. Repeater strengthens signals and increases the distance a signal can travel Advantages of Tree Topology
- 4. Because of Secondary Hub, More devices can be attached to a Central Hub and therefore increase the distance a signal can travel Rest of the advantages are almost the same as STAR Example Tree Topology: Cable TV CABLE TV Main cable from main office is divided into many branches and each branch is divided into smaller branches and so on Drop Line is the connection between device and the main cable (Backbone) Tap is a connector that; Splices into the main cable or Punctures the sheathing of a cable to create connection with the metallic core Signal degrades as it travels; therefore there is a limit on: The number of Taps a Bus can support and the distance between those Taps Advantages of BUS TOPOLOGY Easy to install Backbone can be laid on the most efficient path and then rest of the nodes can be connected using Drop Lines Less cabling required than Mesh ,Star or Tree Disadvantages of BUS Topology Difficult Reconfiguration
- 5. Adding new devices may require modification of backbone No Fault Isolation A fault or break in backbone can disable communication even on the same side of the problem damaged area reflects signals back Each device has point-to-point dedicated link with only two devices on either side A signal is passed in the ring in one direction from device to device until it reaches its destination Each device has a repeater incorporated: when a device receives a signal destined for another device, it regenerates the bits and passes them along Advantages of Ring Topology Easy to Install and Reconfigure Only two connections to be moved to add or delete a device SIMPLE Fault Isolation Generally a signal is circulating at all times in a ring. If one device does not receive a signal within a specified period, it can issue an alarm to tell network operator about the problem and its location Disadvantages of Ring Topology unidirectional Traffic A break in a ring I.e. a disabled station can disable the entire network Can be solved by using: Dual Ring or A switch capable of closing off the Break