Switch means "switch" is a network device used to forward electrical (optical) signals. It can provide an exclusive electrical signal path for any two network nodes connected to the switch. The most common switch is an Ethernet switch. Other common ones include telephone voice switches, optical fiber switches, and so on.
The switch is a very widely used network device, a local area network with multiple network devices, the switch is an indispensable device.
Various switch interfaces
The interface of the switch is very rich. Here are some sorted materials to share with you.
1、RJ-45 interface
This kind of interface is our most common network device interface, commonly known as "crystal head", the professional term is RJ-45 connector, which belongs to the twisted pair Ethernet interface type. The RJ-45 plug can only be inserted in a fixed direction, and a plastic shrapnel is provided to block the RJ-45 socket to prevent it from falling off.
This interface can be used in 10Base-T Ethernet, 100Base-TX Ethernet, and 1000Base-TX Ethernet. The transmission medium is twisted pair. However, depending on the bandwidth, there are different requirements for the medium, especially 1000Base- For TX Gigabit Ethernet connection, at least Cat 5e cable should be used, and Cat 6 cable should be used to ensure stable high speed.
2, SC optical fiber interface
The SC optical fiber interface has been used in the 100Base-TX Ethernet era, so it was called 100Base-FX (F is the abbreviation of fiber). However, because the performance was not more prominent than the twisted pair cable but the cost was higher at that time, so It has not been popularized. Now the industry is vigorously promoting the gigabit network, and the SC optical fiber interface is receiving attention again.
There are many types of optical fiber interfaces. SC optical fiber interfaces are mainly used in local network switching environments. This type of interface is provided on some high-performance Gigabit switches and routers. It looks very similar to the RJ-45 interface, but the SC interface appears flatter The obvious difference is the contact piece inside. If it is 8 thin copper contacts, it is an RJ-45 interface, if it is a copper pillar, it is an SC fiber interface.
3, AUI interface
AUI interface is specially used to connect thick coaxial cable. Early network cards had such interfaces to connect with hubs and switches to form a network, which is generally not used now.
The AUI interface is a "D" 15-pin interface, which was previously used in a token ring network or a bus network. It can be connected to a 10Base-T Ethernet network with the help of an external transceiver repeater (AUI-to-RJ-45) Connection.
4, FDDI interface
FDDI is the highest transmission rate among the current mature LAN technologies. It has the characteristics of a timing token protocol, supports a variety of topological structures, and the transmission medium is optical fiber.
Fiber Distributed Data Interface (FDDI) is a set of protocols developed by the American National Standards Institute (ANSI) to send digital signals on optical cables. FDDI uses dual-ring tokens, and the transmission rate can reach 100Mbps.
CCDI is a variant of FDDI, it uses twisted-pair copper cable as the transmission medium, and the data transmission rate is usually 100Mbps.
FDDI-2 is an extended protocol of FDDI, which supports voice, video and data transmission. It is another variant of FDDI, called FDDI full duplex technology (FFDT). It uses the same network structure as FDDI, but the transmission rate can reach 200Mbps .
Since the use of optical fiber as a transmission medium has many advantages such as large capacity, long transmission distance, and strong anti-interference ability, it is often used in metropolitan area networks, campus environment backbone networks, and multi-building network distribution environments, so the FDDI interface is in the network backbone switch The above is more common, and now with the popularity of Gigabit, some high-end Gigabit switches are also beginning to use this kind of interface.
5, Console interface
This interface, as we know it, is used to configure the switch, so it is only available for the managed switch. Also note that not all network-managed switches have it, because there are many ways to configure the switch, such as through Telnet command line, Web, TFTP, and so on. Although in theory, the basic configuration of the switch must be through the Console (control) port, but the basic configuration of some brands of switches has been configured at the factory, and there is no need to perform basic configuration such as IP address and basic user name. Therefore, this type of network management switch does not need to provide this Console interface, and it still accounts for the majority at present. This kind of switch usually only needs some advanced configuration through simple Telnet or Java program Web.
Of course, some switches still provide a Console interface, but it should be noted that the Console port used for switch configuration is not the same for all switches. Some use the same RJ-45 console interface as the Cisco router.
Switch connection method
Because the switch is mainly used as a centralized connection of LAN devices, in general, the hardware connection is relatively simple, usually only the corresponding transmission medium connector is inserted into the corresponding switch interface. The following only briefly introduces the connection method of switch cascade.
This is the most commonly used way to connect multiple switches. It is connected through the cascade port (UpLink) on the switch. It should be noted that switches cannot be cascaded indefinitely. If more than a certain number of switches are cascaded, it will eventually cause a broadcast storm and cause a serious decline in network performance. Cascade is divided into the following two types:
Use common port cascade
The so-called ordinary port is to connect through a common port of the switch (such as RJ-45 port). It should be noted that the connecting twisted pair used at this time should be reversed, that is, the two ends of the twisted pair should be jumpered (the first 1-3 and 2-6 pins are swapped). The connection diagram is shown in the figure
Use Uplink port cascade
In all switch ports, there will be an Uplink port next to it, as shown in Figure 2. This port is specially provided for uplink connection. You only need to connect the port to any port on other switches except the "Uplink port" through a straight-through twisted pair cable (note that it is not the interconnection of Uplink ports).