The network is connected to the stand-alone device and allows them to share information and resource connectivity systems. Correct design and implementation of a network system can improve the speed and reliability of communication, making a system work more efficient. The construction of the network should meet the requirements of the published national and international standards, and should be able to conduct constant evolution and upgrades according to the changes in business requirements.
With a large number of computers, people are increasingly paying attention to the topics of the network and wiring. Previously, IT managers' concerns about the communication system were limited to telephones. Conversively now, they have to face more complex, faster computing and information systems. In the past, desktop computers are often independent, and this situation has changed. About 50% of commercial computers currently can greatly improve work efficiency in the local area network. The LAN can connect your computer to the server and peripherals, or provide signal channels for sensors, cameras, monitors, and other electronic devices. If these links are temporary, then the workspace will soon be full of various unrecognizable cables, which is almost impossible to troubleshoot and maintain them.
Integrating electronic devices for completing tasks such as computing, building safety, and environmental controls into an integrated system will have greater benefits. When the number of these independent devices increases, the advantages of these devices work together will be more obvious. Of course, the demand for device link will also increase accordingly. For companies that already have complex computer systems, the situation is also changing. From a traditional host and microcomputer to the client, the transformation of the server system means that the dedicated network will be replaced by the open system.
The use of networks is also expanded to new areas. Many managers will face the issue of how to formulate wiring strategies for network security systems, video conferencing systems, and multimedia information systems. Since the status of the network is constantly expanding in this way, all management personnel need to know the knowledge of the network.
First, the strategy of network construction
The choice of network and cable type is mainly determined by the type of device that needs to be connected, their location and their usage method. Before you start planning, give the potential load instructions for networks. When a network is a plurality of system services, the peak of their mixed data traffic should be carefully considered.
For a complete new system, the main job of load assessment is to calculate the number of network nodes, asking each department under the "worst case". When replacing an existing system, the system should be monitored for a week or longer monitoring before planning replacement. When the upgrade of the software is also part of the system upgrade, such as upgrading the computer from the DOS environment to the Windows environment, the complex assessment of the network will be difficult. However, software vendors may give an assessment of network communication traffic. In the planning phase, the planning of future demand and the planning of the current demand should be placed on the same important position.
The average target life cycle of the wiring system is 15 years, which is consistent with the renovation cycle of the main buildings. During this time, the system's computer hardware, software and usage methods will have a major change. The requirements of network throughput, reliability, and safety must be increased.
In the early stage of network construction, as an important part of the work, professionals should also develop detailed technical indicators for networks. Developing a rough technical indicator for network and wiring is an error that IT administrators are committed. Inspected networks may cause the system to crash, the cost will be very high, so excessive funding in the installation phase of the network is an unwise practice.
Some key factors should be considered when developing a network detailed technical indicator:
• Usage, including mixed data stream flow sizes and peak load duration of all applications
• Users and possible growth rates
• The location of the user and the longest distance between them
• Possible probability that the user location changes
• Connection with current and future computer and software
• Available space for cable wiring
• Total investment of network owners
• Regulations and safety requirements
• Prevent service loss and importance of data disclosure
Second, the choice of network configuration is designed
There are three commonly used data network topologies. They are ring nets, bus networks and stars. The ring network, as described in the name, is to connect each device with a continuous ring. It ensures that the signals sent on one device can be seen by all other devices on the ring. In a simple ring network, damage to any part in the network will cause a system to fail, which will hinder the entire system to perform normal operation. The annular network with advanced structures has greatly improved this lack. Token ring
An example of a ring network is token ring, its transmission rate of 4 Mbit / s and 16 Mbit / s, which is the first to IBM, but now is used by other manufacturers. In the token ring network, the device with "token" allows data to be transferred in the network. This ensures that only one device in the network can transmit information in a certain time.
2. Bus network
The bus shaped network uses a certain length of cable, which is the necessary high-speed communication link to connect the device. The device can be taken from the bus without affecting other equipment in the system. The most important implementation in the bus-shaped network is Ethernet, which has now become the standard of local area network. The device connected to the bus is checked by the information transmitted on the bus. When the two devices want to send data in the same time, collision phenomena will occur on Ethernet, but using a protocol called carrier-listening multiple access / collision monitoring (CSMA / CD) can minimize the negative impact of collisions.
3. Star Network
The composition of the star network will be connected to the point through the central device. In the telephone network, this central structure is PABX. In the data network, this device is a host or hub. In the star mesh, the equipment can be greatly increased without affecting other equipment of the system.
Third, wiring noun
• 100Base-T4: Using 4-wire to 100Mbit / s fast Ethernet of 3 types of cables.
• 100Base-TX: Using the 2-wire 5-way cable to fast Ethernet.
• 100VG-Anylan: The first 100Mbit / s local area network for the use of Hewlett-Packard and AT & T developed.
• 10Base-T: Using a non-shielded twisted pair (UTP) cable to meet the transmission rate of 10 Mbps (same as the Ethernet) (IEEE) 802.3 (IEEE) 802.3 (IEEE) 802.3 (IEEE).
• Temporary wiring system: Different types of wiring components produced by multiple manufacturers to achieve wiring system solutions.
• Analog Transmission: Use continuous variables and direct physical measurements (such as voltages, etc.) to indicate signal transmission mode.
• Apply: A system that is supported by its associated transmission.
• Application layer: The highest layer of the open system interconnect model (OSI) (7th floor). This layer is mainly used to support user applications and responsible for communication between applications, such as email applications, file transfer applications, and more.
• Asynchronous: Two or more signal sources use separate clock signals, so they have different frequencies and phases.
• Asynchronous data transfer: a way to transfer data, a digital or alphabetic symbol (represented by 7 to 8-bit binary numbers), to form a 7/8-bit method (number) Data transfer is implemented on the transport medium.
• Asynchronous Transfer Mode (ATM): A high-speed, unit-based switching technology, which uses a variety of techniques to put voice, data, and video signals such as fixed packets (units). These units are transmitted along the exchange path, which is not reached in the fixed order (so asynchronous this term).
• Attenuation: As the length of the transmission line or the increasing increase in the radio wave transmission distance causes the signal to reduce the phenomenon. • Dan: A component of the integrated wiring system, including a main cable wiring and corresponding facilities for supporting from the device to the floor, or between the same layer.
• Balanced circuit: A circuit used to generate the same and reverse signals, which feed these signals into two wires. The better the balance characteristics of the circuit, the smaller the scatter of the signal, the better the noise suppression characteristics (so its EMC performance is better).
• Balance twisted pair cable: includes a cable of a pair or more metal symmetric cable unit (twisted pair or four stranded pair).
• Unbalance transformers: A device for impedance matching between balance and non-balanced lines is usually used between twisted pairs and coaxial cables.
• Bandwidth: The range of available frequencies used to transmit information on one channel. It is an indicator for representing channel transmission capabilities. Therefore, the wider bandwidth, the greater the amount of information that the circuit can transmit. The bandwidth unit is Hz, Bit / S or MHz.km (for fiber).
