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2.4 UNDERSTAND MEDIA ACCESS CONTROL (D) WAN TOPOLOGY (Wide area networks,…
2.4 UNDERSTAND MEDIA ACCESS CONTROL
2.4.1 DESCRIBE THE VARIOUS COMPUTER NETWORK TOPOLOGIES
A) PYSICAL TOPOLOGY
refers to the interconnected structure of a local area network (LAN)
connect the physical devices on the network with the cables, and the type of cabling used, all constitute the physical topology
TYPES OF PYSICAL TOPOLOGY
Linear Bus Topology
: A single cable to which all network nodes are directly connected. The cable has terminators at each end to prevent the loss of signal.
Star Topology
: A topology with a single access point or a switch at the center of the topology; all the other nodes are connected directly to this point.
Tree (Extended Star) Topology
: A combination of both the star and the linear bus topologies. This topology has multiple access points connected to the linear bus, while the nodes are connected to their respective access points.
B) LOGICAL TOPOLOGY
concept in networking that defines the architecture of the communication mechanism for all nodes in a network
Using network equipment such as routers and switches, the logical topology of a network can be dynamically maintained and reconfigured.
COMMON LOGICAL TOPOLOGY
Bus topology
: Ethernet uses the logical bus topology to transfer data. Under a bus topology a node broadcasts the data to the entire network. All other nodes on the network hear the data and check if the data is intended for them.
Ring topology
: In this topology, only one node can be allowed to transfer the data in a network at a given time. This mechanism is achieved by token (the node having token only can transmit the data in a network) and hence the collision can be avoided in a network.
C) LAN TOPOLOGY
LAN physical topology defines the geographical arrangement of networking devices.
A point-to-point connection is a direct link between two devices.
5 BASIC MODELS
Bus Topology
: All the devices/nodes are connected sequentially to the same backbone or transmission line. This is a simple, low-cost topology, but its single point of failure presents a risk.
Star Topology
: All the nodes in the network are connected to a central device like a hub or switch via cables. Failure of individual nodes or cables does not necessarily create downtime in the network but the failure of a central device can. This topology is the most preferred and popular model.
Ring Topology
: All network devices are connected sequentially to a backbone as in bus topology except that the backbone ends at the starting node, forming a ring. Ring topology shares many of bus topology's disadvantages so its use is limited to networks that demand high throughput.
Tree Topology
: A root node is connected to two or more sub-level nodes, which themselves are connected hierarchically to sub-level nodes. Physically, the tree topology is similar to bus and star topologies; the network backbone may have a bus topology, while the low-level nodes connect using star topology.
Mesh Topology
: The topology in each node is directly connected to some or all the other nodes present in the network. This redundancy makes the network highly fault tolerant but the escalated costs may limit this topology to highly critical networks.
D) WAN TOPOLOGY
Wide area networks, or WANs, provide network communication services in the workplace, connecting locations that can be spread out anywhere in the world.
Flat
~ A small company with few locations might implement a flat topology. For a company with four locations, each site might be connected on the WAN to two other sites located in different states or countries. The physical transport used for a flat WAN can involve leased lines, microwave and fiber optic service.
Full Mesh
~ A full mesh topology relies on every site’s WAN router having a connection to every other site on the wide area network. Full mesh topologies provide a high degree of dependability and fault tolerance, which can come at a high price tag.
Partial Mesh
~ A variation to a full mesh involves a partial mesh topology. This design introduces a hierarchical approach to the topology that can be applied when designing international networks, offering flexibility to establish variations in the topology to meet geographic needs.
Star
~ A star topology involves a central location serving as the hub in the design, with sites branching off the hub like spokes on a wagon wheel. In a star topology, a failure to one hub location will not affect the other sites on the WAN.