Shulou(Shulou.com)06/02 Report--

Principle and configuration of switch

In our previous study, we know that network transmission is divided into seven levels. The second layer is the data link layer, and the typical one in the data link layer is the switch! So today I'm going to introduce you to the switch at the data link layer. What is its principle? How to configure it?

I. functions of the data link layer

1. Establishment, maintenance and dismantling of data links

two。 Frame wrapper, frame transmission, frame synchronization

3. Error recovery of frames (parity)

4. Flow control and self-adaptation

2. Ethernet MAC address

The MAC address has a total of 48 bits

The first 24 bits are the supplier identification, and the last 24 bits are the unique identity information of the network card.

The destination address can be understood as the destination MAC address; the source address can be understood as the sender's MAC address; the type is used to identify the type of upper layer protocol, such as 0800H identifies the IP protocol.

III. Basic principles of the switch

The forwarding principle of the switch

Switch records source MAC and corresponding port number

There is a MAC address table in the switch indicating the MAC address and the corresponding port k890

Finding the destination MAC by broadcast will flood other ports except the receiving port

Dynamic learning

Static binding (manual setting)

Diffusion of MAC address table * *: use multiple different MAC to fill the MAC address table, causing all the data frames normally sent later to become broadcasts

MAC resists the indefinite aging time of 300s for static binding of dynamically learned MAC addresses only.

Fourth, the duplex mode of switch interface

Simplex: data transmission in a single direction

Half-duplex: two-way data transmission, but not simultaneously

Full-duplex: two-way data transmission, allowing synchronization.

F1AX 1 fastEthernet Fast Ethernet 100m Ethernet 10m

Front 1: veneer number

Followed by 1: interface number

E0/1/2

0: box number

1: veneer number

2: interface number

Some commonly used commands in the switch

Enable user layer-privilege layer disable privilege layer-user layer

Config t privilege layer-global layer int f1amp 0 global layer-interface layer

No ip roating shuts down the router function

User layer-privilege layer-global layer-interface layer

You can only go deep into the end layer by layer, but you can go directly back to the privilege layer exit and go back to the previous layer.

The transmission process of the second layer in the switch is a difficulty. If we want to find out the logical relationship inside, we will find that it is not difficult to find the trick.

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