Topologies
What is topologies ???
Topology from the
Greek is mean place and study,this
is a major area of
mathematics concerned with properties that are preserved under
continuous deformations of objects, such as deformations that involve stretching, but no tearing or gluing. It emerged through the development of concepts from
geometry and
set theory, such as space, dimension, and transformation.
Topology includes many subfields. The most basic and traditional division within topology is
point-set topology, which establishes the foundational aspects of topology and investigates concepts inherent to topological spaces for basic examples include
compactness and
connectedness is
algebraic topology, which generally tries to measure degrees of connectivity using algebraic constructs such as
homotopy groups and
homology; and
geometric topology, which primarily studies
manifolds and their embeddings (placements) in other manifolds. Some of the most active areas, such as
low dimensional topology and
graph theory, do not fit neatly in this division.
What is network topologies ???
Network topology is the layout pattern of interconnections of the various elements links and nodes of a computer or biological network. Network topologies may be physical or logical. Physical topology refers to the physical design of a network including the devices, location and cable installation. Logical topology refers to how data is actually transferred in a network as opposed to its physical design. In general physical topology relates to a core network whereas logical topology relates to basic network.
A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more nodes in the network and the mapping of these links and nodes in a graph results in a geometric shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flow between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.
The type of network of topologies :
But I want to introduce just three network topologies such as ring topology, bus topology and star topology.
Ø Ring Topology
Ring topology is a ring network in the network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.
Advantages
Data is quickly transferred without a ‘bottle neck’. (very fast, all data traffic is in the same direction.
The transmission of data is relatively simple as packets travel in one direction only.
Adding additional nodes has very little impact on bandwidth
It prevents network collisions because of the media access method or architecture required.
Disadvantages
Data packets must pass through every computer between the sender and recipient therefore this makes it slower.
If any of the nodes fail then the ring is broken and data cannot be transmitted successfully.
It is difficult to troubleshoot the ring.
Because all stations are wired together, to add a station you must shut down the network temporarily.
In order for all computers to communicate with each other, all computers must be turned on.
·
Ø Bus Network
A bus network topology is a network architecture in which a set of clients are connected via a shared communications line, called a bus. There are several common instances of the bus architecture, including one in the motherboard of most computers, and those in some versions of Ethernet networks.
Advantages
Easy to implement and extend
Well suited for temporary networks (quick setup)
Initially less expensive than other topologies
·
Difficult to administer/troubleshoot.
Limited cable length and number of stations.
If there is a problem with the cable, the entire network goes down.
Maintenance costs may be higher in the long run.
Performance degrades as additional computers are added or on heavy traffic.
Low security (all computers on the bus can see all data transmissions).
One virus in the network will affect all of them (but not as badly as a star or ring network).
Proper termination is required.(loop must be in closed path).
If one node fails, the whole network will shut down.
If many computers are attached, the amount of data flowing causes the network to slow down.
Ø Star Network
Star network are fairly easy to install and maintain. Nodes can be added to and removed from network with little or no disruption the nertwork.
Advantages
Disadvantages
Expensive to install
Extra hardware required
