answer:
*Ring Topology
Ring topology is consists of a single cable that forms the main data path in the shape of a ring. each devices are connected in the shape of a closed loop of cable,so that each device is connected directly to two other devices,one on either side of it. Signals travel in one direction from one node to all other nodes around.
* Mesh topology
is a variation of the bus,which devices are connected with many redundant interconnections between network nodes. In mesh topology every node has a connection to every other node in the network. Each node is capable of transmitting, receiving, and routing data.
* Star Topology
star topology is a form of LAN architecture that all devices are connected to a common central hub or switch, and this is done by the use of dedicated links and also nodes communicate across the network by passing the data through the hub.
* Bus Topology
A bus topology creates a network by connecting 2 or more hosts to a length of coaxial backbone cabling. In this topology, both ends of the network must be terminated with a terminator .Also bus topology is still regarded as one of the major network topologies of the networking world. It is often used when network installation is small, simple or temporary.
* Tree Topology
by all other nodes.
The Tree topology is a hybrid topology of the bus and star layouts. The basic topology is similar to that of a bus, which nodes connected in sequence to a linear bus backbone or central cable. But tree networks may have "branches" that contain multiple workstations that are connected point-to-point in a star-like pattern. Signals from a transmitting node travel the length of the medium and are received
2. What are the discription of of 7 ISO layer?
Answer:
Layer 7:Application Layer
It defines the interface to user processes for communication and data transfer in network. Provides standardized services such as virtual terminal, file and job transfer and operations, It is also used for applications specifically written to run over the network ,allows access to network services that support applications; directly represents the services that directly support user applications.
Layer 6: Presentation Layer
Application Layer entities, in which the higher-layer entities can use different syntax and semantics, as long as the presentation layer service understands both and the mapping between them. The presentation they also receive data from application layer. Mask the differences of data formats between dissimilar system, and specifies architecture-independent data transfer format.
Layer 5:Session Layer
The Session Layer manage and controls the user session and dialogues/connections between computers. establishes, manages and terminates the connections between the local and remote application and report upper layer errors.
Layer 4: Transport Layer
The transport provides transparent transfer of data between end users,and providing reliable data transfer services to the upper layers. The Transport Layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Transport Layer can keep track of the segments and retransmit those that fail and provides connectionless packet delivery.
Layer 3: Network Layer
The network layer provides the functional and procedural means of transferring variable length data sequences from a source of destination via from one or more networks, The Network Layer performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors
Layer 2: Data Link Layer
The Data Link Layer provides the functional and procedural means to transfer data between network entities. They defines procedure for operating the communication links. Frames packets,detect and correct packets transmit errors. And this layer was intended for point-to-point and point-to-multipoint media, characteristic.
Layer 1:Physical Layer
A physical Layer is defines of sending data over network devices,and Interfaces between network medium and devices,Also defines optical electrical and mechanical characteristic.
