General Cabling Basics

Networks are connected systems that connect separate devices together and enable them to share information and resources. The correct design and implementation of a network system can improve the speed and reliability of communication, so that a system to work more efficiently. The construction of the network should meet the requirements of the published national and international standards, and should be able to evolve and upgrade according to changes in business requirements.

With the great use of computers, people pay more and more attention to the topic of network and wiring. Previously, IT managers ' concerns about communication systems were limited to telephones. Now, they have to face more complex, faster-changing computing and information systems. In the past, desktop computers were usually working independently. Now that has changed. At present, more than 50% of the commercial computers are connected to the local area network, they can greatly improve the efficiency. A local area network can connect a computer to a server and peripheral, or provide a signal channel for sensors, cameras, monitors, and other electronic devices. If these links are based on a temporary basis, the workspace will soon be full of all sorts of indistinguishable cables, and it is almost impossible to troubleshoot and maintain them.

Integrating electronic devices, such as computing, building safety, and environmental control, into an integrated system will yield greater benefits. When the number of these stand-alone devices increases, the benefits of these devices working together are more pronounced. Of course, the need for equipment links will also increase correspondingly. The situation is also changing for companies that already have complex computer systems. The shift from traditional mainframe and microcomputers to client/server systems means that private networks will be replaced by open systems.

The use of the network is also being extended to new areas. For the first time, many managers will face the problem of how to develop routing strategy for Network security system, Video conferencing system and multimedia information system. As the status of the network continues to expand in this way, all management personnel need to understand the knowledge of the network. (Computer science)

The strategy of network construction

The choice of network and cable types is primarily determined by the type of devices that need to be connected, their location, and how they are used. Before you begin planning, it is necessary to give a description of the potential load on the network. When a network serves multiple systems, the peaks of their mixed data traffic should be considered carefully.

For a complete new system, the main task of load assessment is to compute the number of network nodes and ask the departments to use the "worst case" requirements. When an existing system is replaced, the system should be monitored for one weeks or longer before the replacement is planned. When software upgrades are part of a system upgrade, such as upgrading a computer from a DOS environment to a Windows environment, it is difficult to make a complex network assessment. However, software vendors may then give an assessment of network traffic. In the planning phase, planning for future needs and planning for the present needs should be placed on an equal footing.

The average target life cycle for cabling systems is 15, which is consistent with the refurbishment cycle of major buildings. During this time, there will be significant changes in the system's computer hardware, software, and usage patterns. The requirements for network throughput, reliability, and security must be increased.

In the initial stage of network construction, as an important part of the work, professionals should also develop detailed technical indicators for the network. Making rough technical metrics for your network and cabling is a common mistake IT administrators make. Immature networks can cause systems to crash and will be costly, so it is unwise to save money excessively during the installation phase of the network.

The following key factors should be considered when developing network detailed technical indicators:

• Usage, including mixed data flow flow size and peak load duration for all applications

• Number of users and possible growth rates

• The user's location and the longest distance between them

• Possible probability of change in user location

• Connections to current and future computers and software

• Free space for cabling

• Total investment by network owners

• Regulatory and safety requirements

• The importance of preventing service loss and data leaks

Selection Essentials for network configuration

At present, there are three kinds of data network topologies in common use. They are ring nets, total linear networks and star-shaped nets. A ring net, as the name describes it, uses a continuous loop to connect each device together. It ensures that the signals sent on a single device can be seen by all the other devices on the ring. In a simple ring network, the damage of any part of the network will cause the system to fail, which will hinder the whole system to work properly. However, the annular network with advanced structure has greatly improved the defect.

Token Ring

An example of a ring network is a token ring LAN, which has a transmission rate of 4mbit/s and 16mbit/s, which was first introduced by IBM, but is now adopted by other manufacturers. In a token ring network, a device with a "token" allows data to be transmitted over the network. This ensures that only one device in the network can transmit information at a given time.

Total Linear Network

The total linear network uses a certain length of cable, which is the necessary high-speed communication link to connect the devices together. The device can be removed from the bus without affecting other devices in the system. The main implementation of the total linear network is Ethernet, which has become the standard of the LAN at present. A device connected to the bus checks the data sent to itself by monitoring the information transmitted on the bus. Collisions occur on Ethernet when two devices want to send data at the same time, but using a protocol called carrier interception multiple Access/collision monitoring (CSMA/CD) can minimize the negative impact of collisions.

Star Network

The composition of the star network connects many point-to-point connections through a central device. In the telephone network, this central structure is PABX. In a data network, this device is a host or hub. In a star network, you can easily add and reduce devices without affecting the work of other devices in the system. adjourned

Wiring nouns

100BASE-T4 uses 4-line MBIT/S Fast Ethernet for 3-class cables.

100BASE-TX uses 2-line MBIT/S Fast Ethernet for 5-class cables.

100vg-anylan the mbit/s LAN, which was first developed by Hewlett-Packard and AT&T, using the requirement priority protocol.

10 base-t uses unshielded twisted pair (UTP) cables to meet the Electronic and Electrical Engineers Association (IEEE) 802.3 standard (same as Ethernet) transfer rate of Mbps LAN.

• Temporary wiring system will be produced by a number of manufacturers of different types of wiring components to achieve cabling system cabling system scheme.

• Analog transmissions use continuous variables and direct physical measurements (such as voltages) to represent signal transmission patterns.

• The application of a system with its associated transmission mode is supported by the telecommunication wiring system.

• The highest level (layer 7th) of the application layer Open Systems Interconnection model (OSI). This layer is primarily used to support user applications and to manage communications between applications, such as e-mail applications, file transfer applications, and so on.

• Asynchronous two or more signal sources use separate clock signals, so they have different frequencies and phases.

• Asynchronous data transmission a way to transmit data, a number or letter sign (represented by 7 to 8 digits) preceded by a starting or ending bit, resulting in a 7/8-bit approach to data transfer on a (digital) transmission medium.

• Asynchronous Transfer Mode (ATM) a high-speed, cell-based exchange technology that uses a variety of techniques to place signals such as voice, data, and video in fixed-length packets (units). These units are transmitted along the exchange path, and they do not reach the receiver in a fixed order (and therefore use the term asynchronous).

Attenuation of signal decreases as transmission line length or radio transmission distance increases.

• An integral part of the trunk cabling system, including a main cable wiring and corresponding facilities to support connections between the equipment and the upper floors, or the same floor.

• The balance circuit is used to generate the same and opposite signals, and it feeds these signals into two wires. The better the balance of the circuit, the smaller the scattering of the signal, and the better the noise suppression (hence the better EMC performance).

• Balanced twisted pair cable consists of a pair or more pairs of metal symmetrical cable units (twisted pair or four stranded wire) cable.

• Unbalanced transformers are used to achieve impedance matching between balanced and unbalanced lines, usually between twisted and coaxial cables.

• The range of frequencies available for transmission of information on a single channel. It is used to express the capacity of the channel transmission indicators. Therefore, the wider the bandwidth, the greater the amount of information the circuit can transmit. The unit of bandwidth is Hz, bit/s, or mhz.km (for fiber).

In the last period we mentioned, whether it is a token network, a bus network or a star network, mainly refers to the logical topology structure of the network. However, in practical applications, the physical topology of all these networks is usually a star-shaped connection, and the star connection has more flexibility when connecting users to the network. This advantage becomes more pronounced when the system is evolving or the system has undergone significant changes. The star shape, the total linear and the ring network all have their own characteristics, and the final choice of the network structure depends to a great extent on the current application. However, the stellar physical topology is a kind of physical topological structure commonly used in industrial and commercial networks.

The most popular 10base-t Ethernet is currently running on a balanced UTP copper cable, which has a data transfer rate of mbit/s. This form of Ethernet is quite popular in most office and industrial applications. The 10BASE-T network uses a star physical topology, with a small number of buses on the hub hub. As with other LAN systems, computers connected to the 10BASE-T and other active devices must be equipped with a network card.

As an upgraded form of 10BASE-T, 100BASE-T's data transfer rate is 100mbit/s, which is a higher-speed Ethernet. 100BASE-T has a wider range of applications. Upgrading from 10BASE-T to faster versions of Ethernet requires the replacement of network adapters, hubs, and, in some cases, the need to replace new cables.

ATM uses fast packet switching technology to transmit latency-sensitive data in a star network, which can transmit speeds up to 622mbit/s or higher. The optical fiber Distributed Data Interface (FDDI) is a high-speed token ring network, and it is 100mbit/s on the optical fiber. FDDI system can have two complete fiber ring, can provide a certain degree of redundancy protection in the bad environment. Use a balanced UTP cable to achieve the same 100mbit/s transfer rate as FDDI. This network is called TP-PMD (based on twisted-pair physical media).

And the specialized system is the third type of network general structure. Such networks are usually introduced before standards-based networks are established, and private network systems typically use only products from specific network product vendors. Most of these products are derived from IBM and Wang Computer, which use a star topology. These networks initially use expensive dual-axis or coaxial shielded cables. Now, in many cases, they can operate on a balanced UTP cable with a balanced adapter (usually an unbalanced transformer).

Another kind of wiring system is serial communication system. They are typically used to perform tasks that connect terminals and computers directly to small machines, hosts, and peripherals, at a low rate. Strictly speaking, this kind of connection is not a real network. However, serial communication can be connected to a structured wiring system and can be routed through hubs and trunk lines. To do this, you need to use a passive adapter or an active interface device. There are two main forms of serial communication. Asynchronous serial communication works at the rate of 38.4 kbit/s, while synchronous serial communication works at a 64kbit/s rate. Both types need to be connected through a serial port.

In the network construction, use the trunk cable to connect the network segments together, so that the network can provide service in the larger area without increasing the wiring. Using the main Trunk line, a single hub can be assembled together as a unit to work on a high-speed link. If the main line fails, a separate subnet will continue to work independently. Trunk cables can use thick, thin, UTP twisted-pair cables or optical cables. However, in the common wiring standard, it is recommended to use a multi-membrane fiber or UTP twisted-pair cable as the trunk cable. To build a large network, you can connect any type of stand-alone LAN to a trunk cable, bridge, or router. In Ethernet, hubs are usually concentrated in a separate room for security and convenience. In this case, the length of the trunk line is the shortest, and the system is often considered to be a folding trunk network. Like Ethernet, the Token Ring network can be connected together to form a large network, and two token Ring networks require routers to connect.

In the installation of many cabling systems, users can choose to install a new network or repair an existing network. The latter scenario usually saves a lot of investment, but it relies on existing cabling systems and new network access methods. However, temporary networks using hybrid cabling systems for historical reasons or for investment reasons have great drawbacks. Today's structured cabling system can use a range of adapters to interconnect with all major hardware devices. This will allow already built networks and new networks to benefit from the latest cabling technology.

Selection of wiring

Cabling is one of the key components of any networked system, so policymakers must be prepared to use 10% of total network investment in this area. Network failures due to poor design and unqualified installation are the most common and costly, so investment in high quality cabling and network design is definitely worth it.

The type of device connected to the network and the traffic load on the cable are key factors in selecting the cable. Also, you should consider the following factors when making cable selections:

• Maximum distance between a network hub and a node (information port)

• Free space in piping and floor/ceiling wiring

• Degree of electromagnetic interference (EMI)

• Possible changes to the devices that serve the system and how they are used

• The level of system Recovery force

• Life cycle of network requirements

• Limitations of cable alignment and cable bending radius

• Possible use of existing cable installation with potential repeatability

Cable selection should take into account the above factors, but in the wiring system should first determine whether the use of shielded cables, unshielded cables, optical cables, or the joint use of them. Cables usually use wires with insulating layers and use one or more layers of plastic skins. A cable typically consists of 2 to 1800 line pairs. Large-logarithmic cables are commonly used in backbone cabling systems, which are particularly suitable for use in voice and low speed data applications.

The maximum length of these cables in the application of the trunk and level (hub to desktop) cabling system is described in detail in the International standard ISO/IEC IS11801. It is important to note that these maximum length limits apply to all media. They do not consider the impact of performance differences due to the different cable types and protocol types used by the network. In fact, the maximum cable length will depend on the system's application, network type (such as 10BASE-T), and cable quality. In a specific network, good cable suppliers and construction personnel will be able to provide appropriate advice on cabling system capabilities.

It is also important to check the free space for cable alignment before determining the type of cable. Factors such as size, weight and shielding flexibility depend mainly on whether the cable is metal foil or the preparation of the shield, and how many wires are used in the cable. These factors, along with the shielding/reflection material used in the cable, will determine the power of the cable against EMI (EMI). Before selecting a cable, it is also critical to consider the shielding/reflective material used by the cable.

In recent years, breakthroughs in the study of unshielded twisted pair (UTP) cables have enabled them to transmit data at 622mbit/s or higher transmission rates. This makes it possible to use a lower, smaller cable in an application that uses only shielded cables. UTP cables reduce EMI interference by more closely matching cables to the wire. This cable is called the balance circuit. In an ideal balance circuit, the noise voltage introduced in the conductor is zero, so that the signal transmission between the line pairs will not interfere. However, this ideal situation is not fully implemented, the cable signal-to-noise ratio (SNR) is used to measure the cable in the presence of noise signals in the case of signal quality indicators. Shielding cable due to the existence of shielding, so its balance is poor, so good shielding integrity and good grounding for shielded cable is very important. High-quality UTP cable can achieve good balance circuit characteristics without grounding or the whole circuit need not be shielded. Because optical fibers transmit signals through light waves, they are unaffected by any form of electromagnetic shielding.

In applications where the transmission rate requires more than 155mbit/s and require longer transmission distances, the fiber is usually the best choice. Optical fiber has the advantages of small size and durability, but at present its cost is higher than other types of cable. Most of the optical cables used in the LAN are the multi-membrane fiber. It is easier to install than high-performance single film fiber. In most networks, cable is generally used as a trunk line, and UTP cable is used to level. However, as communication speeds increase and equipment prices drop, the number of networks that use fiber directly to the desktop is growing. Wireless LANs can be an alternative to systems that do not easily install cables due to installation time, space, or other limitations. The use of radio waves to replace physical connections in wireless LANs enables signal transmission, which is particularly suitable for the installation of networks in old buildings.