Network layout principle

The humidity of the machine room shall be kept at 20%-80%, and the temperature of the machine room shall be kept at 15℃-35℃. Installing air conditioner to adjust the temperature is the best way to solve this problem. Only by planning and designing the wiring system of the computer room can the network equipment have a good "home". The IT network should interconnect the computer room and the office space through the wiring system to ensure the normal operation of the network. If there are many access points in the enterprise, we can adopt the design of three network levels: access layer, convergence layer layer and switching layer, and carry out wiring system on this basis. For the access layer, selecting a reasonable access device is the most critical, and the appropriate bandwidth should be selected according to the access device. Convergence layer is the core part of the whole LAN, and the network equipment in convergence layer generally supports the network management function, which is convenient for our management and maintenance, and also convenient for our future network upgrade and transformation. The switching layer is the middle layer in the whole network, connecting convergence layer and network nodes, and it is a very important link that determines the transmission quality of our whole network. With the popularization of 100M network equipment, 100M is definitely the first choice for our switching layer network equipment. Wiring is an important link connecting network access layer, convergence layer, switching layer and network nodes. It is best to use a dedicated channel when wiring, and do not mix wiring with radiation lines such as power lines and air conditioning lines. For twisted pair between access layer and convergence layer, you can choose more than five kinds of shielded twisted pair to maximize network performance. The twisted pair between convergence layer and the switching layer, because it is the layer with the largest network data transmission, also uses super five shielded twisted pair. Between the switching layer and the network nodes, we can use ordinary super five-layer unshielded twisted pair. Network equipment should be placed in the center of the node, not to save the cost of integrated wiring, but to improve the overall performance and transmission quality of the network. Because the transmission distance of twisted pair is 100 meters, the best network transmission quality can be obtained at 95 meters. When doing network wiring, it is best to design a computer room to place network equipment. Planning and Design of Network Layout Most network devices are rack-mounted (mostly flat, like drawers), such as switches, routers, hardware firewalls, etc. The reason why these devices have such structural types is that they are all designed according to international cabinet standards, so that everyone's plane dimensions are basically uniform and can be installed together in a large vertical standard cabinet. The benefits of doing this are obvious: on the one hand, it can make the equipment occupy the smallest space, on the other hand, it is convenient to connect and manage with other network devices, and at the same time, the computer room will look neat and beautiful. There are network cabinets, server cabinets and integrated wiring cabinets that we often come into contact with in the storage room. From the names of these three cabinets, we can see their respective functions. Generally speaking, switches, routers, firewalls, encryption machines and other network equipment, optical terminals, modems and other network communication equipment are placed in the network cabinet; The width of the server cabinet is 19 inch, and the height is in u (1U= 1.75 inch =44.45 mm), and there are usually 1U, 2U, 3U and 4U servers. The size of the cabinet also adopts general industrial standards, usually ranging from 22U to 42U; There is a detachable sliding supports in the cabinet according to the height of U. Users can flexibly adjust the height according to the elevation of their own servers to store servers, hubs, disk array cabinets and other equipment. After the server is placed, all its I/O lines are led out from the back of the cabinet (all interfaces of the rack server are also at the back) and placed in the trunking of the cabinet in a unified way, which is usually labeled for easy management. The integrated wiring cabinet is generally equipped with front and rear movable mounting posts, and the installation space can be freely set, and accessories such as partitions, fans and power sockets can be configured as required. Distribution frame is usually installed in the cabinet, and one side of the distribution frame is RJ45 port and marked with number; On the other side is the jumper interface, which is also marked with numbers. These numbers correspond to the RJ45 port number above. Each group of jumpers are marked with four colors: brown, blue, orange and green. The color lines of twisted pair should correspond to these jumpers one by one, so it is not easy to connect them wrong. Distribution frame is not only convenient to manage the pair, but also can prevent crosstalk, increase the isolation space of the pair and provide 360-degree isolation of the pair. Switches, functional server groups and network printing equipment, as well as various devices needed to connect the local area network to the Internet, such as routers, firewalls, network management workstations, etc., must be placed in the computer room. Therefore, the network layout of the computer room generally has at least three cabinets. The integrated wiring cabinet and the network cabinet should be closely connected to facilitate wiring operation, followed by the server cabinet; Reasonable layout of network equipment and wiring system. In the network layout, it is best to leave a certain space for each cabinet to facilitate the expansion of network equipment and server equipment in the future. In addition to network wiring, there may be telephone lines in the integrated wiring cabinet, so it is necessary to leave some space in the cabinet. From the cable accessories inside the cabinet, the cabinet has a higher configuration density, accommodates more IT equipment, and uses a large number of redundant accessories (such as redundant power supply and storage array). ), frequently change the equipment configuration in the cabinet, and increase or decrease the data lines and cables at any time. Therefore, the cabinet must provide enough cable channels to access cables from the top and bottom of the cabinet. Cable laying in the cabinet must be convenient and orderly, close to the cable interface of the equipment, so as to shorten the wiring distance; Reduce the space occupation of cables, ensure that the equipment is not disturbed by wiring during installation, adjustment and maintenance, and ensure that the cooling airflow is not hindered by cables; At the same time, in the case of failure, it can quickly locate the equipment wiring. Power supply system and refrigeration system are two important parts of the computer room. In the power supply system, online UPS power supply mode is generally adopted. The actual available capacity of the battery is closely related to the discharge current, the ambient operating temperature of the battery, the storage time and the nature of the load (resistance, inductance and capacitance). Refrigeration system (air conditioning) involves the whole physical environment of the computer room, including air conditioning, floor, cabinet and room layout. So we should also consider putting UPS and air conditioner in the right place. If the room is large, you can put UPS and air conditioner in the room. If the space is small, you can put UPS (including batteries) in the power distribution room. It should be noted that if "central air conditioning" is installed in the building, the computer room must also be equipped with independent air conditioning, because the central air conditioning can not be turned on all the time and can be used during working hours. When the server and network equipment need to run normally after work and on weekends and holidays, the independent air conditioner in the computer room must be turned on. The expansion of cabinets is manifested in the expansion of equipment density and the expansion of the number of cabinets, so the air supply capacity (usually called heat dissipation capacity) and power distribution capacity of cabinets must be considered in the network layout. On the one hand, the equipment in the cabinet needs cold air (cold air) with appropriate temperature and humidity and sufficient air volume. These cold air are sucked by the IT equipment in the cabinet, thus cooling the components (especially CPU) in the equipment. When the number of equipment in the cabinet increases to a certain amount, the amount of cold air sent by the floor outlet will not meet the needs of all equipment, resulting in overheating of some IT equipment due to insufficient airflow distribution. To solve this local hot issue when the equipment density in the cabinet increases, it can be solved by deploying the location of IT equipment. For example, the equipment with the largest heat load is installed in the middle of the cabinet to obtain the largest air distribution. Another solution is to install an axial horizontal strong exhaust fan in the upper or lower part of the cabinet to enhance the suction capacity of the upper or lower part (that is, to reduce the static pressure at the entrance of IT equipment), thus increasing the air distribution. On the other hand, the equipment in the cabinet needs power supply and communication with the outside of the cabinet. When the number of IT equipment in the cabinet increases, these cables and connecting terminals increase exponentially at the same time, which puts forward expansion requirements for the capacity of rack power supply and the number of sockets. The wiring space in the cabinet also needs to be considered in advance, because when the power density in the cabinet increases, the wind resistance of cables behind the equipment will increase obviously, so cable management and wiring space must be considered.