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A network topology describes the arrangement of computer network. It defines how the workstation, or nodes, within the network are arranged and connected to each other. It is the physical interconnections of the links or nodes of a computer network.
It has five ordinary topologies. There will be reliable for the in-house network (LAN). There are:
- Bus topology
- Star topology
- Ring topology
- Tree topology
- Mesh topology
There are also three main categories of topologies:
- physical topologies
- signal topologies
- logical topologies
The signal topologies and the logical topologies are often used interchangeable. The physical topology of network is the actual geometric arrangement of workstations. It is the design of wiring, cables, the locations of nodes, and the interconnections between the nodes and the cabling or wiring system.
In the bus topology, each node is connected to a central bus that runs along the whole network. Each node is directly connected to the rest of the node in the network. All information transmitted across the bus, so can be received by any nodes in the network.
In the star topology, one central node or server workstation to which each of the other nodes on a network are directly connected. All information transmitted across the central nodes.
In the ring topology, each node is directly connected to other two nodes on a network and other pair of nodes is indirectly also connected. It can be imaged as a circular arrangement. The data are passing through one or more intermediate nodes.
In the tree topology, one node of star topology network is directly connected to node of another network. The tree topology is also combination of the bus topology and the star topology. Unlike the star topology in the tree, some nodes may indirectly connect to the central node.
The mesh topology has two designs called full mesh and partial mesh. In the full mesh topology, each node directly connected to rest nodes in a network. In the partial mesh, some nodes directly connected to rest nodes in a network and some nodes directly connected to some nodes in a network.
Physical network medium is the type of cabling, that is used in a network. There are many types of cables used in networks today. Copper wire, Radio transmission lines and fibre optic cable are three main mediums of computer network communication.
Wireless LAN has two types of architecture; there are Ad-Hoc Network and Infra Mode Network. Ad-Hoc Network is used in network which has a few nodes and there must be closely located. It architecture require only one wireless NIC for each nodes.
Infra Mode Network is also called infrastructure mode. That network architecture is used in large wireless LAN. It may include at last one wireless router and many nodes. Wireless connection has many advantages; it used a smaller amount of space, no cabling needed between nodes, easy to expend, nodes can be mobile and not fix in one location on a network, wide bandwidth and multichannel transmissions. The length of wireless connectivity area is larger than wire connection.
Wireless LAN devices are expensive. And so many kind of interrupt wave may disrupt to wireless connection than other media networks when the data transmission. It's easy to accept and big weakness point is less security. But it can be backup way to connect with a few devices when fail the main connection.
Fibre optic cable is popular for high speed network. It can support many channels at tremendous speed. But it is very expensive and almost never used in LAN.
Copper wire involves many type of wire. But twisted pair and coaxial cable are popular. Coaxial cable, also know as coax is designed with two conductors; thick coax and thin coax. Thick coax is stiff and heavy cable that is used as a network backbone for the bus network. Thick coax is difficult to work with and it is quit expensive.
Thin coax is common type of Coaxial. Thin coax is quite flexible and has low impedance. It is capable of faster transmission than twisted-pair cable. It is supporting several networks on the same cable. But it supports only a single channel. It is high attenuation rate makes it expensive when long distance. Now a day these two coax cables are not useful, because of these tow coax cables are more reliable with Bus topology.
The common and standard type of network media is twisted pair cable. It consists of two insulated wires twisted around each other and may include one pair to 4200 pair in a cable. In unshielded twisted pair (UTP), each wire is insulated with plastic wrap, but the pair is encased in an outer covering. Category 5 UTP cable is standard type of most Networks. Category 5 cable includes 4 pair and jack is RJ-45.
Every electronic device has little or more weakness. So, twisted pair has little weakness points; exist a little crosstalk, susceptibility to interference and noise, attenuation problem is repeaters, routers needed every 2km or 3km, relatively low bandwidth (3000Hz), capable of slower transmission than coaxial, require direct peer to peer connections. (p2p connection require cross cable of UTP)
But it has so many advantages. It is a thin, flexible and light weight cable that is easy to string between walls. Easy to work with and install. It does not quickly fill up wiring ducts, costs less per meter/foot than any other type of LAN cable. It is inexpensive but readily available. Maximum data rate is 1000Mbps in 1000BaseTX cable. If cable length is 100m (328 ft), we will get high transmission rate and high security in a network.
Recommendation for Topology and Media
The topology of highly recommend for the Townsville police department is the Star topology. The topology offers simplicity of operation. It also achieves an isolation of each device in the network. Many benefits will get using the star topology.
Easy to replace, install or remove nodes or other devices. Each device needs only one link and one ports to connect it to any number of nodes; one device per connection.
The star topology is no difficulty to make configurations, ease of service. It has a number of concentration points. These provide easy access for service or reconfiguration of the network. Good performance and reliable. Robust as failure of one link does not affect the whole system. The remaining of system will be active.
It has simple access protocols. Any given connection in a star network involves only the central node. Thus in a star network, access protocols are very simple.
Recommend for network media is Unshielded Twisted Pair (UTP) cable. Because of it is common standard of computer networking and reliable to install. It is really cheap and really easy to work with. So highly recommend network media for large and secure network is UTP cable.