Network Topology

Network –network is used generally to mean a set of computers that are connected together in such a way as to permit them to communicate and share information. 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. − mapping of the elements of a network gives rise to certain basic topologies which may then be combined to form more complex topologies (hybrid topologies). − the way that the devices on a network are arranged and how they communicate with each other. − way that the workstations are connected to the network through the actual cables that transmit data Basic types of topologies • Bus (Linear, Linear Bus) • Star • Ring • Mesh Classification of network topologies • signal topologies

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partially connected mesh (or simply 'mesh') fully connected mesh Tree (modified by tayeb) Hybrid

logical topologies

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physical topologies

Signal topology − mapping of the actual connections between the nodes of a network, as evidenced by the path that the signals take when propagating between the nodes. − often used synonymously with the term 'logical topology', Example: Signal topology is a bus (i.e., the electrical signal propagates to all nodes simultaneously [ignoring propagation delays and network latency]), and the logical topology is a ring (i.e., the data flows from one node to the next in a circular manner according to the protocol) Logical topology – mapping of the apparent connections between the nodes of a network, as evidenced by the path that data appears to take when traveling between the nodes. − the way that the signals act on the network media, or the way that the data passes through the network from one device to the next without regard to the physical interconnection of the devices. − bound to the network protocols that direct how the data moves across a network. Classification of logical topologies •

logical classification of network topologies generally follows the same classifications as those in the physical classifications of network topologies, the path that the data takes between nodes being used to determine the topology as opposed to the actual physical connections being used to determine the topology.

Notes: 1.) Logical topologies are often closely associated with media access control (MAC) methods and protocols. 2.) The logical topologies are generally determined by network protocols as opposed to being determined by the physical layout of cables, wires, and network devices or by the flow of the electrical signals, although in many cases the paths that the electrical signals take between nodes may closely match the logical flow of data, hence the convention of using the terms 'logical topology' and 'signal topology' interchangeably.

3.) Logical topologies are able to be dynamically reconfigured by special types of equipment such as routers and switches. Example: Ethernet protocol is a common logical bus topology protocol, provides a single channel (or bus) that carries Ethernet signals to all stations. LocalTalk is a common logical bus or star topology protocol. IBM's Token Ring is a common logical ring topology protocol. Physical topologies − mapping of the nodes of a network and the physical connections between them – i.e., the layout of wiring, cables, the locations of nodes, and the interconnections between the nodes and the cabling or wiring system. Classification of physical topologies Point-to-point − simplest topology is a permanent link between two endpoints. − simplest and most straightforward. − a chain of devices and another name for this type of connectivity is called daisy chaining. − connects two nodes directly together. • •

Most computers can 'daisy chain' a series of serial devices from one of its serial ports. Networks of routers are often configured as point-to-point topologies. Most often a communications connection between two devices over a single hardware connection that is not shared by any other devices. There will be exactly two and only two devices on the connection. Networks using point-to-point topologies can be daisy-chained together to form an end-to-end communications path.

 Permanent (dedicated) − easiest to understand, of the variations of point-to-point topology, is a point-to-point communications channel that appears, to the user, to be permanently associated with the two endpoints. Point to Multipoint − a single connection point on the network has network segments that run to several other points. − all transmissions from all devices pass through the hub--the hub broadcasts all communication from any single device to all other devices connected to it. − the hub can send to one or more systems based on an address. Switched: Using circuit-switching or packet-switching technologies, a point-to-point circuit can be set up dynamically, and dropped when no longer needed. This is the basic mode of conventional telephony. Example: • Two computers communicating via modems. • A mainframe terminal communicating with a front end processor. • A workstation communicating along a parallel cable to a printer. Submitted by: Liafe D. Angco Submitted to: Mrs. Ma. Luisa N. Francisco Subject: NET1 (Introduction in Networking)