3Com 4210 PWR Configuration Manual page 160

158 C 14: MSTP C
HAPTER
Configuring the Mode a
Port Recognizes and
Sends MSTP Packets
ONFIGURATION
During the selection of the root bridge, if multiple switches have the same
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bridge priority, the one with the smallest MAC address becomes the root
bridge.
Configuration example
# Set the bridge priority of the current switch to 4,096 in spanning tree instance 1.
<4210> system-view
[4210] stp instance 1 priority 4096
A port can be configured to recognize and send MSTP packets in the following
modes.
Automatic mode. Ports in this mode determine the format of the MSTP packets
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to be sent according to the format of the received packets.
Legacy mode. Ports in this mode recognize/send packets in legacy format.
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802.1s mode. Ports in this mode recognize/send packets in dot1s format.
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A port acts as follows according to the format of MSTP packets forwarded by a
peer switch or router.
When a port operates in the automatic mode:
The port automatically determines the format (legacy or dot1s) of received
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MSTP packets and then determines the format of the packets to be sent
accordingly, thus communicating with the peer devices.
If the format of the received packets changes repeatedly, MSTP will shut down
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the corresponding port to prevent network storm. A port shut down in this
way can only be brought up by the network administrator.
When a port operates in the legacy mode:
The port only recognizes and sends MSTP packets in legacy format. In this case,
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the port can only communicate with the peer through packets in legacy
format.
If packets in dot1s format are received, the port turns to discarding state to
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prevent network storm.
When a port operates in the 802.1s mode:
The port only recognizes and sends MSTP packets in dot1s format. In this case,
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the port can only communicate with the peer through packets in dot1s format.
If packets in legacy format are received, the port turns to discarding state to
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prevent network storm.
Configuration procedure
Table 106 Configure the mode a port recognizes and sends MSTP packets (in system
view)
Operation
Enter system view
Command
system-view
Description
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