Geography of computer networks

" Topology" is a mathematical idea that abstracts physical entities into points independent of their size and shape, and the lines connecting them into lines, therefore studying the relationships between points, lines, and surfaces.

Computer networks likewise utilize topology research study methods to define the gadgets in the network as nodes, the connection in between the two gadgets is defined as a link. From a topological viewpoint, a computer network is a geometry consisting of a set of nodes and links, and this geometry is the topology of the computer network, which reflects the structural relationships between the various entities in the network. Network geography style is the primary step to develop a computer network, but also the basis for carrying out different network procedures, which has a fantastic impact on the network performance, dependability, and interaction costs.

The network topology can be divided into four types according to the geometric shape: bus topology, ring geography, star topology, and mesh topology. These shapes can likewise be mixed to form a hybrid topology. Different network topologies appropriate for different network sizes. For example, LAN applications are bus, star, or ring topologies, while WANs utilize mesh geographies.

1.1 Star Topology

In a star topology, each node in the network is linked through a central gadget, such as a hub. Each node in the network sends data to the central gadget, which in turn forwards the data to the target node. Any single cable in a star network links only 2 gadgets (e.g., a workstation and a hub or switch), and a problem with the cable affects up to two nodes. Therefore a failure of a single cable or node will not lead to a breakdown of communication for the whole network. Nevertheless, the failure of a central gadget will cause a star network to be down. Central nodes enforce a central interaction control policy and are for that reason rather complicated and challenging.

In a star topology, any 2 websites need to be managed by the main node to communicate.

The primary functions of the main node are:

• ① Establish a physical connection for the equipment that needs to interact;
• ② Maintain this channel for the two gadgets in the interaction procedure;
• ③ When communication is completed or unsuccessful, the channel is eliminated.

Benefits of star geography:

1. The network structure is simple, easy to manage, centralized control, and easy to network;
2. Short network delay time and low bit mistake rate;
3. The network sharing ability is poor, the usage rate of interaction lines is low, and the central node is overloaded;
4. It can link several media such as twisted set, coax cable, and fiber optics at the same time.

Drawbacks of star geography:

1. Extremely high requirements on the central node (consisting of the reliability and redundancy of the central node);.
2. If the central node fails, a large area of the network may be paralyzed;.
3. The central node is strained, the structure is more complex, and bottlenecks are prone to appear.
4. The system has poor security and bad resource sharing efficiency.

1.2 Ring topology.

The ring geography is composed of network nodes linked into a closed-loop, and each node is linked to its left and right surrounding nodes.

Ring networks typically use the token ring to determine which nodes can access the communication system. In a ring network, information flow can only be unidirectional, and each station that receives a details packet forwards the information packet to its downstream station. The information package "travels" in the ring network and is lastly recycled by the sending station. When the information package passes the target station, the target station judges that it is a receiving station according to the target address in the details package, and copies the details to its receiving buffer. In order to figure out which station on the ring can send information, a special info package called a token circulates on the ring. Just the station that has the token can send out information. When a station ends up sending the info, it transfers the token down so that downstream stations can get the chance to send out the info.

The attributes of the ring network are:

The info flows in a set of instructions in the network, and there is just a distinct path in between 2 nodes, which considerably streamlines the control of path choice. When a node fails, it can be automatically bypassed, which has high reliability. As with the bus topology, when the number of nodes in the ring increases, the action time becomes longer. Therefore, the pure ring topology is very inflexible or not easy to expand. In addition, in a basic ring topology, a single node or cable failure will cause the whole network to be disabled. Therefore, some networks adopt a double-ring structure to supply fault tolerance. A ring network is likewise one of the commonly used topological structures of computer system local area networks, suitable for information processing systems and factory automation systems. The IBM token ring launched by IBM in 1985 is its design.

Benefits of ring geography:

1. The status of each workstation is equal;.
2. There is no channel choice issue in the system;.
3. There will be no disputes and jams in network information transmission.

Downsides of ring topology:

1. The dependability is low, and the failure of the node will trigger the failure of the whole network;.
2. Trouble in fault medical diagnosis;.
3. It is not easy to reconfigure the network;.
4. When there are too many nodes in the ring, it will affect the information transmission rate.

1.3 Bus topology.

The design method that utilizes a central primary cable television called a bus to link workstations connected in a linear way is called bus geography.

In the bus structure, all online computers are straight connected to the bus through the matching hardware user interface. The information of any node can be transmitted and diffused in 2 instructions along the bus. When one node sends information to another node, all nodes will passively listen to the data, only the target node will receive and process the information sent out to it, and other nodes will disregard the data. This resembles a broadcast station, so the bus network is also called a broadcast network.

Benefits of bus geography:

1. Basic and flexible structure, easy to broaden;.
2. High reliability and quick network reaction speed;.
3. The quantity of devices is little, the rate is low, and the installation and usage are convenient;.
4. The capability to share resources is strong, which is convenient for broadcast work, that is, one node sends out and all nodes can receive.

Drawbacks of bus geography:

1. Trouble in fault diagnosis;.
2. It is difficult to isolate faults, any node failure may trigger network problems;.
3. Poor real-time performance;.
4. When the network scale is large, the transmission efficiency drops considerably.

The gadgets linked at both ends of the bus are called terminator (end impedance matcher or terminator). Primarily carry out impedance matching with the bus, to maximize the absorption of the energy of the transmission end, and prevent the signal from reflected back to the bus and cause unnecessary interference.

The network-based on the bus topology is simple to carry out, and the construction expense is extremely low, but its scalability is poor. When the variety of nodes in the network increases, the efficiency of the network will reduce. In addition, the fault tolerance of the bus network is poor, and the disruption or failure of a node on the bus will affect the data transmission of the entire network. For that reason, few networks adopt a pure bus topology.

1.4 Mesh geography (also referred to as dispersed geography).

In the network topology, every two nodes are straight interconnected. Mesh geography is often used in wide area networks. In this case, nodes refer to geographical locations. Since each area is adjoined, data can be sent straight from the sending place to the destination. If a connection fails, the data transmission path will be changed easily and rapidly. Considering that numerous links are attended to information transmission between two points, the mesh topology is the most fault-tolerant network topology.

One disadvantage of mesh geography is cost. Linking each node in the network with other nodes needs a large number of devoted lines.

It ought to be pointed out that in real networking, the topological structure is not always single, but is typically a mix of a number of structures.

Advantages of mesh topology:

1. With high dependability, when one line is faulty, it will not affect the operation of the whole system;.
2. Hassle-free resource sharing and short network reaction time.

Drawbacks of mesh geography:

Since the node is likewise connected to multiple nodes, it is hard to select and manage the flow of the node routing, the management software is made complex, and the hardware expense is high.