The switch in our impression is as a LAN node connected network equipment, in fact it also exists in the WAN, and has been a large number of applications, especially in telecommunications operators, ATM switches and now Fibre Channel switches, but we usually find it difficult to see such switches. However, this article is still mainly to our common LAN switch as an example to introduce all kinds of switch interface and connection mode.
LAN switch as a centralized connection device of LAN, its interface type is with the development of various local area network and transmission medium type, analyze the main network type of LAN and the development process of transmission medium, we are not difficult to discover various switch interface type, Let's begin by introducing some of the switch interfaces that are still present, and note that because many of the switches have the same interface as the router, this is still covered by the corresponding interfaces on the router.
Type of Switch interface
1. Twisted-pair Cable RJ-45 interface
This is one of the most widely used interface types we see, and it belongs to the twisted-pair Ethernet interface type. It is used not only in the most basic 10base-t Ethernet networks, but also in the current mainstream 100BASE-TX Fast Ethernet and 1000BASE-TX Gigabit Ethernet. Although the transmission media they use are twisted-pair types, but they used different versions of twisted-pair types, such as the 3 line used initially by 10BASE-T to support the 6-class line of 1000BASE-TX gigabit, and the middle 100base-tx to use the so-called five-and five-class lines, Of course, it can also be a six class line. The appearance of these RJ-45 interfaces is exactly the same, as shown in Figure 1 on the left, like a flat "T" word. Connected with the RJ-45 Crystal Head, as shown in Fig. 2, the right figure is a crystal head and a good crystal head wiring twisted pair of cable. As shown in Figure 2, this is an Ethernet switch with a 24-port RJ-45 interface, with 2 SC fiber interfaces and a AUI interface that will be described below.
Figure I
Figure II
2. Fiber Optic interface
For optical fiber This transmission medium although early in the 100Base era has begun to use this kind of transmission media, at that time this hundred-gigabit network in order to and commonly used in the hundred-gigabit twisted-pair Ethernet 100BASE-TX difference, it is called "100base-fx", which "F" is the fiber "Fiber" The first letter. But because at the time of the hundred mega-rate, compared with the use of traditional twisted-pair media, the advantages are not obvious, and the price is much more expensive than twisted pair, so the optical fiber in the 100Mbps era has not been widely used, it is mainly from the implementation of 1000Base technology has been fully applied since, because at this rate, Although there are twisted-pair media scheme, but the performance is not as good as fiber, and in connection distance and so have a very obvious advantage, very suitable for metropolitan area network and WAN use.
At present, the optical fiber transmission medium development is quite rapid, each kind of fiber interface is also the layer does not investigate, but in the LAN switch, the fiber interface mainly is the SC type, whether in the 100base-fx, or in the 1000BASE-FX network. SC interface Core in the connector, as shown in Fig. 3, is a 100BASE-FX network SC Fiber Interface module, the right image of a 4 sc fiber optic interface of the fiber switch. There are also 2 SC fibre interfaces in the switches shown in Figure 2.
Figure Three
From Figure 2 and Figure 3, the SC interface appearance of the switch shows that it is very similar to the RJ-45 interface, but the SC interface appears to be more flat and the gap is shallow. Mainly look at the contact chip is what type, if it is 8 copper shrapnel, it is RJ-45 interface, and inside if a copper column is SC fiber interface.
3. AUI interface and BNC
The AUI interface is specifically designed to connect to a thick coaxial cable, although this kind of network does not see much in the local area network at present, but in some large enterprise networks, there may still be some thick coaxial cable token network devices left over, so some switches also keep a few AUI interfaces to meet the user's needs more greatly. The AUI interface is a 15-pin "D"-shaped interface, similar to the display interface. This interface is also seen in many network devices, such as routers, and even servers, as shown in Figure 4, is the AUI interface diagram on the router.
Figure Four
BNC is an interface specifically designed to connect to a thin coaxial cable, and the switches currently available for this interface are relatively rare. However, a few BNC interfaces are also available in some RJ-45 Ethernet switches and hubs, specifically for token network connections with thin coaxial cables as transport media. To show you the true appearance of BNC, here's a BNC interface card to show you, as shown in Figure 5.
