Network Topology
Topology refers to the shape of a network, or the network's layout. How different nodes in a network are connected to each other and how they communicate are determined by the network's topology. Topologies are either physical or logical. Below are diagrams of the five most common network topologies
2. Examples of Network Topology, their Definition and post example picture.
Mesh Topology
Devices are connected with many redundant interconnections between network nodes. In a true mesh topology every node has a connection to every other node in the network.
Star Topology
All devices are connected to a central hub. Nodes communicate across the network by passing data through the hub.
Bus Topology
All devices are connected to a central cable, called the bus or backbone.
Ring Topology
All devices are connected to one another in the shape of a closed loop, so that each device is connected directly to two other devices, one on either side of it.
Tree Topology
A hybrid topology. Groups of star-configured networks are connected to a linear bus backbone.
3. What is OSI Layer?
- Open System Interconnection, an ISO standard for worldwide communications that defines a networking framework for implementing protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.
At one time, most vendors agreed to support OSI in one form or another, but OSI was too loosely defined and proprietary standards were too entrenched. Except for the OSI-compliant X.400 and X.500 e-mail and directory standards, which are widely used, what was once thought to become the universal communications standard now serves as the teaching model for all other protocols.
4. Examples of OSI Layer, their definition in order.
Application Layer 7
It is employed in software packages which implement client-server software. When an application on one computer starts communicating with another computer, then the Application layer is used. The header contains parameters that are agreed between applications. This header is often only sent at the beginning of an application operation.
Presentation Layer 6
This provides function call exchange between host operating systems and software layers. It defines the format of data being sent and any encryption that may be used, and makes it presentable to the Application layer.
Session Layer 5
The Session layer defines how data conversations are started, controlled and finished. The Session layer manages the transaction sequencing and in some cases authorisation. The messages may be bidirectional and there may be many of them, the session layer manages these conversations and creates notifications if some messages fail. Indications show whether a packet is in the middle of a conversation flow or at the end. Only after a completed conversation will the data be passed up to layer.
Transport Layer 4
This layer is resonsible for the ordering and reassembly of packets that may have been broken up to travel across certain media. Some protocols in this layer also perform error recovery. After error recovery and reordering the data part is passed up to layer 5.
Network Layer 3
This layer is responsible for the delivery of packets end to end and implements a logical addressing scheme to help accomplish this. This can be connectionless or connection-oriented and is independent of the topology or path that the data packets travel. Routing packets through a network is also defined at this layer plus a method to fragment large packets into smaller ones depending on MTUs for different media (Packet Switching). Once the data from layer 2 has been received, layer 3 examines the destination address and if it is the address of its own end station, it passes the data after the layer 3 header to layer 4.
Data Link Layer 2
This layer deals with getting data across a specific medium and individual links by providing one or more data link connections between two network entities. End points are specifically identified, if required by the Network layer Sequencing. The frames are maintained in the correct sequence and there are facilities for Flow control and Quality of Service parameters such as Throughput, Service Availability and Transit Delay.
Physical Layer 1
This layer deals with the physical aspects of the media being used to transmit the data. The electrical, mechanical, procedural and functional means This defines things like pinouts, electrical characteristics, modulation and encoding of data bits on carrier signals. It ensures bit synchronisation and places the binary pattern that it receives into a receive buffer. Once it decodes the bit stream, the physical layer notifies the data link layer that a frame has been received and passes it up.
5. What is Networking?
Networking
- In the world of computers, networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.
6. Example of Networking, Post at least 5 examples with picture.
Complex Networking
Peer to Peer Networking
Metropolitan Area Networking
Local Area Networking
Wide Area Networking
