WEEK 6~ network topology

NETWORK TOPOLOGY

is the study of the arrangement or mapping of the elements (links, nodes, etc.) of a network, especially the physical (real) and logical(virtual) interconnections between nodes


Physical topology
Any given node in the LAN will have one or more links to one or more other nodes in the network and the mapping of these links and nodes onto a graph results in a geometrical shape that determines the physical topology of the network

Logical Topology :
the mapping of the flow of data between the nodes in the network determines the logical topology of the network.


LINEAR BUS

-A linear bus topology consists of a main run of cable with a terminator at each end.
-All nodes (file server, workstations, and peripherals) are connected to the linear cable.
-Ethernet and LocalTalk networks use a linear bus topology.


STAR

-A star topology is designed with each node (file server, workstations, and peripherals) connected directly to a central network hub or concentrator .
-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


STAR-WIRED RING

-A star-wired topology may appear (externally) to be the same as a star topology.
-Internally, the MAU (multistation 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.


TREE

-A tree 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.


MESH

Mesh topologies involve the concept of routes. Unlike each of the previous topologies, messages sent on a mesh network can take any of several possible paths from source to destination. (Recall that even in a ring, although two cable paths exist, messages can only travel in one direction.) Some WANs, most notably the Internet, employ mesh routing.
A mesh network in which every device connects to every other is called a full mesh. As shown in the illustration below, partial mesh networks also exist in which some devices connect only indirectly to others.


Hybrid;

Hybrid networks use a combination of any two or more topologies in such a way that the resulting network does not exhibit one of the standard topologies (e.g., bus, star, ring, etc.). For example, a tree network connected to a tree network is still a tree network topology. A hybrid topology is always produced when two different basic network topologies are connected. Two common examples for Hybrid network are: star ring network andstar bus network.


Daisy chain;

Except for star-based networks, the easiest way to add more computers into a network is by daisy-chaining, or connecting each computer in series to the next. If a message is intended for a computer partway down the line, each system bounces it along in sequence until it reaches the destination. A daisy-chained network can take two basic forms: linear and ring.