Wirless topology

5. Wirless topology

Wireless topologies seem odd at first because there are no physical wires to guide you to the actual topology shapes that they use. In fact, wireless topologies are implemented in a star, a mesh, or a cellular configuration. In the star configuration, the wireless topology is called a Basic Service Set (BSS). It consists of a wireless access point connected to a wired network, and it enables each wireless device to connect to the access point and through it to all other devices.

In the case of the mesh configuration, the wireless network, the Independent Basic Service Set (IBSS), enables each wireless device to connect to any other wireless device within range.

In the cellular topology, the wireless network, referred to as an Extended Service Set (ESS), consists of a series of overlapping wireless cells, each with its own WAP. Devices can actually move among cells and continue working seamlessly, regardless of which cell they happen to be in. It’s easiest to think of this as a radio station. Imagine you’re driving down a long road and you have your radio tuned to 95.5 FM. As you go along, you eventually fade out of 95.5 FM for one area, but you fade into 95.5 FM for the next area. If these two stations were playing the exact same program, you wouldn’t even know that you had changed from one to another.

Ring topology

4) Ring topology

In this topology, each computer is connected to the next, and the final device is connected back to the first so that the entire system is a closed loop.

                Any single devices on the ring is connected directly two neighboring devices at all time. There are both single ring topology and dual ring topology.

                Data travel around the ring in a single direction, either   clockwise or counterclockwise direction. In dual ring system, data can travel in both direction to speed up through put.

                Unlike bus topology, ring topology required n caballing termination because the cable never really starts and end.

Mesh topology

3) Mesh topology  

This topology is unique, and a true mesh topology is practically none exists. Most of the network that claims to be mesh topology to be mesh topology   is actually partial meshes. In a true, mesh each network devices must have a separate point-to-point connection to every devices in the mesh. For a three node mesh there are three connections, for four nodes there are 6 connections, in 5 nodes there are 10 connection and so on.

                It is extremely very useful when you want to be absolutely certain that data from one network node will reach any other network node in the mesh.

                If a single point-to-point connection fail, the data can travel through a different node and reach it’s final destination.

star topology

1) star topology

In this topology, each and every device (computer) has its own cable switch, multiple point repeaters, or sometime multiple access point (MAU).Data is passed through the hub, repeater, or switch to reach other device or network.

                Ethernet over unshielded twisted pair (up to), whether it is 10baset, 100baset, or gigabit, all use a star topology.

                It is most common in network. This is mainly because it is easy to troubleshoot and configure. If a single wire or cable or single port on a hub or switch goes bad/or failure, it will not bring down the network. Only the failure nodes will go down, which prevents the huge impact on the network.

Unless the entire hub, or switch fails, in which case, the whole lan goes down. However because a star topology involves a central hub or switch as well as a lot of cabling. It costs is more to implement.

Benefits

1.       Easy to troubleshoot and configure.

2.       A single wire/device or cable failure will not bring down the network.

Disadvantage

1.       Lots of cabling is required.

2.       If a hub fails, the entire section of the network fails with it.

Bus topology

1) Bus topology

In bus topology, every network device hook directly into a central cable because there is no use of central devices like a hub, switch, repeater etc. So every device is connected to the central wire (acts as a central hub). So the central cable is shared communication medium for every device that tap into it. When the device communicates across the cable, the message is seen by all the other devices, but only the true destination devices will use it.

Benefits of Linear Bus Topology

1)  It is easy to install and extend bus network.
2)  Cable length required for this topology is the least compared to other networks.
3)  Bus topology costs very less than other topology.
4) This types of network is mostly used in small networks. Good for LAN.

Disadvantages of Linear Bus Topology

1)  There is a limit on central cable length and number of nodes that can be connected.
2)  Dependency on central cable in this topology has its disadvantages. If the main cable  encounters
     some  problem, whole network breaks down.
3)  Proper termination is required to dump signals. Use of terminators is must.
4)  It is difficult to detect and troubleshoot fault at individual station.
5)  Maintenance costs can get higher with time.
6)  Efficiency of Bus network reduces, as the number of devices connected to it increases.
7)  This types of network is not suitable for networks with heavy traffic.