Saturday, 19 May 2012

Technology and Topology(2)

lets continue with the topic of topology. Last week I already talk about two topology which are linear bus and also ring topology. So, this time I'm gonna talk about the next topologies which are star, star-wired, tree and also FDDI. 

3) STAR

  • A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub or concentrator.
  • In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages.
  • Data on a star network passes through the hub or concentrator before continuing to its destination. The hub or concentrator manages and controls all functions of the network. It also acts as repeater for the data flow. 
  • This configuration is common with twisted pair cable; however, it can also be used with coaxial cable or fiber optic cable.
  • The protocols used with star configurations are usually Ethernet or LocalTalk. 
  • The star topology reduces the chance of network failure by connecting all of the systems to a central node.
  • The failure of a transmission line linking any peripheral node to the central node will result in the isolation of that peripheral node from all others, but the rest of the systems will be unaffected.
 Advantages
• Easy to install, and wire.
• Easy to add new workstations
• No disruptions to the network when connecting or removing devices.
• Any non-centralised failure will have very little effect on the network
• Easy to detect faults and to remove parts.
• Centralized control

 • Centralized network/hub monitoring


Disadvantages
• Requires more cable length than a linear topology.
• If the hub or concentrator fails, nodes attached are disabled.
• More expensive than linear bus topologies because of the cost of the concentrators.





 4) STAR-WIRED

• A star-wired topology may appear (externally) to be the same as a star topology.
• Internally, the MAU (multi-station access unit) of a star-wired ring contains wiring that allows information to pass from one device to another in a circle or ring
• The Token Ring protocol uses a star-wired topology.

 

5) TREE

• A tree (hybrid) topology combines characteristics of linear bus and star topologies.
• It consists of groups of star-configured workstations connected to a linear bus backbone cable. Tree topologies allow for the expansion of an existing network, and enable schools to configure a network to meet their needs.
 
Advantage
• Point-to-point wiring for individual segments.

Disadvantages
• Overall length of each segment is limited by the type of cabling used.
• If the backbone line breaks, the entire segment goes down.
• More difficult to configure and wire than other topologies.

6) FDDI (Fiber Distributed Data Interface)

• 100mbps
• Normally implemented over fiber optic (fast- Ethernet, UTP)
• Dual redundancy built in by use of primary and secondary ring
• Automatic bypassing and isolation of faulty nodes



1 comment:

  1. hi..Im student from Informatics engineering, this article is very informative, thanks for sharing :)

    ReplyDelete