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

STP: spanning tree protocol-spanning Tree Protocol

-where

In a switched network, that is, on a so-called switch; that is, the technology is a layer 2 technology.

-why

Because in the traditional switching network, there is the problem of "single point of failure".

So in order to solve this problem, we introduced the "backup link / device" solution.

However, it brings a new problem-layer 2 data loop

Therefore, in order to solve this problem, we propose a STP solution.

-Loop formation:

Demo process-draw and understand by yourself.

Loop phenomenon-the following message will be prompted on the switch: MAC A flapping between Fas0/1 and Fas0/2 looks at the LED indicator of the port on the switch to see: blinking madly

-function:

In the switched network, there are backup links to prevent the occurrence of layer 2 data forwarding loops.

-implement:

-message

BPDU-bridge protocol data unit

Bridging protocol data unit

-Typ

Config BPDU: configuring BPDU

TCN BPDU: topology change notification BPDU

-principle

1. Determine the role of the switch

Root switch

Non-root switch

Election basis: BID-bridge ID, Bridge ID

Priority + MAC address

2Byte 6Byte

Election principles:

1. First compare the priority of BID. The smaller the better.

The default is 32768

2. If the priority is the same, compare the MAC address as small as possible.

It is essentially the "base MAC address" of the switch, that is,

MAC address of the motherboard of the switch-show version

2. Determine the role of the port (root-port) root port: on each non-root switch, there is one and only one, from the root switch, the nearest port (designated-port) designated port: in each network segment (collision domain), there is and only one, from the root switch, the nearest port (non-designated-port) non-designated port: all other ports Are called non-designated ports. How to represent "distance" in STP? -cost: cost indicates the distance to the root switch

The Mr.Zero distance is related to the port bandwidth.

Bandwidth cost (default correspondence)

10m-100

100m-19

1G-4

3. Determine the port status down/disable: indicates that the port is closed or hung up. Listening: indicates the listening state, which is the learning that cannot send and receive user data: indicates the learning status, and the state is the forwarding that cannot send and receive user data; indicates the forwarding status, which can be sent and received normally (final state) blocking: indicates the blocking state, which cannot send and receive user data (final state)

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