Shulou(Shulou.com)06/01 Report--

Ladies and gentlemen, in this chapter, I will talk to you about the basic principles and configuration of the switch.

First, let's take a look at what a switch is and its definition:

Switch (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 of the access switch. The most common switch is the Ethernet switch. Other common ones are telephone voice exchange, fiber optic switch and so on. Exchange is a general term of technology in which the information to be transmitted is sent to the corresponding route that meets the requirements by means of manual or equipment automatic transmission according to the needs of transmitting information at both ends of the communication. According to the different working location, the switch can be divided into WAN switch and LAN switch. Wide area switch is a kind of equipment that completes the function of information exchange in the communication system, and it is used in the data link layer. The switch has multiple ports, each of which has a bridging function and can connect to a local area network or a high-performance server or workstation. In fact, a switch is sometimes referred to as a multiport bridge. A network switch, which is a device for expanding the network, can provide more connection ports for the subnetwork in order to connect more computers. With the development of the communication industry and the promotion of national economic informatization, the network switch market is rising steadily. It has the characteristics of high performance-to-price ratio, high flexibility, relative simplicity and easy implementation. Ethernet technology has become the most important LAN networking technology, and the network switch has become the most popular switch. Switch is the English name of the switch. this product is upgraded from the original hub and is not very different from the hub in appearance. Because the two ends of the communication need to transmit information, and through the equipment or manual to send the information to the corresponding router that meets the required standards, this technology is the switch technology. In a broad sense, the equipment that realizes the information exchange function in the communication system is the switch.

The device is an Ethernet switch.

Theory: (two-layer principle)

1. Data link layer function

two。 Ethernet frame format

3. How the switch works

4. Commands of the switch

The two-layer principle lies between the network layer and the physical layer.

One: data link layer functions:

1. Establishment, maintenance and dismantling of data links

two。 Frame wrapper, frame transmission, frame synchronization

3. Error recovery of frame

4. Flow control (QUS)

Second, Ethernet development:

1.X-Wire: 2.94 megabit experimental Ethernet

2.DIX:10 megabit Ethernet application

3.IEEE 802.3: 10 megabit Ethernet standard

4. Gigabit Ethernet: 100 / 1000 megabit Ethernet

Three: Ethernet MAC address (48 bits, 48 binaries)

1. A single device or group of devices used to identify an Ethernet

First 24 bits (supplier identification)

Bit 8 of the first 24 bits: 0-physical address (unicast address)

1-24 bits after the multicast address (the unique number of the network card corresponding to the vendor)

IV: Ethernet frame format:

Preamble (7 bytes)

Start delimiter (1 byte)

Destination address (6 bytes)

Source address (6 bytes)

Type (2 bytes)

Data (46 to 1500 bytes)

Frame check sequence (4 bytes)

It is shown in the following figure:

Introduction to switch equipment:

1.Crsco switching product system: (take Cisco equipment as an example) Crsco2960 series switches Crsco3560 series switches Crsco4500 series switches Crsco6500 series switches (ISP carrier network)

CDN pushes nearby

Dual media: optical fiber and network cable

How the switch works: the forwarding principle of the switch: initial state MAC address learning (recording source MAC address) broadcast unknown data frame receiver response switch to achieve unicast communication

Let's give an example here: for example, we now have a new switch, and there are three PCs under its port 1.2.3. at this time, PC A packages its source MAC address and the destination table MAC address it wants to send into data frames and sends them to the switch through port 1. The first thing the switch does after receiving it is to record the source MAC address of PC A. At this time, the switch does not know which port the target is under, so it can only send it all in the form of a broadcast. At this time, PC B, whose MAC address matches, finds that he is the receiver after receiving the broadcast. At this time, he has to respond to the switch by packaging his MAC address as the source MAC and the MAC address sent to the other party as the destination MAC into a data frame and responding to the switch through port 2. At this time, what the switch does is to record the source MAC address of PC B. at this time, the switch already knows that PC An and PC B need to communicate through ports 1 and 2, so they can unicast communication at this time. The process is shown in the following figure:

The mode of operation of the switch Ethernet interface:

1. Simplex: data can only be transferred in a single direction between two data stations (for example, an external player)

two。 Half-duplex: two-way data transmission between two data stations, but not at the same time (for example, walkie-talkies)

3. Full-duplex: data can be transmitted in both directions and at the same time between two data stations (such as current telephones)

Switch Ethernet interface rate:

1. Negotiate when the interface is connected

two。 If the negotiation fails, it will be impossible to pass.

Preparation before configuration:

Connection before configuration

① console cable

two。 Physical connection

Computer COM

Switch / router Console port

3. Software connection

① HyperTerminal

Other ② softwar

It is shown in the following figure:

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