Cisco switch STP-- solves broadcast Storm

In fact, devices on the network are often constructed into loop networks in order to prevent local paralysis caused by a single line failure, which physically provides conditions for broadcast storms-the solution STP protocol logically forms a tree structure (the cisco switch comes with this protocol)

STP:Spanning tree protocal

Root bridge-> bridge ID judgment, follow port and designated port through the following 2p3 judgment

The data of STP protocol passes through BPDU (bridge protocol unit, default message every 2 seconds), and the data includes root bridge ID, root path cost, bridge ID that initiates BPDU, and port ID that sends messages.

When the switch starts up for the first time, it defaults to the root bridge, receives the BPDU of other sw, compares it, and sends out the root bridge ID.

The following are the STP states in switch port 5

Description: when the switch starts, the port state is listening, and the process of changing the port color from yellow to green is the STP operation.

Enter portfast in the port to cancel the port STP operation, such as the port where the PC is connected to the switch