H3C Technologies H3C S10500 Series Switches - Manual (Page 99)

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Configuring the mode a port uses to recognize/send MSTP
packets
A port can receive/send MSTP packets in the following formats:
• dot1s—802.1s-compliant standard format
• legacy—Compatible format
By default, the packet format recognition mode of a port is auto. The port automatically distinguishes the
two MSTP packet formats, and determines the format of packets that it will send based on the recognized
format.
You can configure the MSTP packet format on a port. When working in MSTP mode after the
configuration, the port sends and receives only MSTP packets of the format that you have configured to
communicate with devices that send packets of the same format.
Follow these steps to configure the MSTP packet format to be supported on a port or a group of ports:
To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface view
interface interface-type
interface-number
Enter
interface
view or port
group view
Enter port group view port-group manual port-group-name
Required
Use either command.
Configure the mode that the port uses to
recognize/send MSTP packets stp compliance { auto | dot1s |
legacy } Required
auto by default.
NOTE:
•
MSTP provides MSTP packet format incompatibility guard. In MSTP mode, if a port is configured to
recognize/send MSTP packets in a mode other than auto, and if it receives a packet in a format different
from the specified type, the port becomes a designated port and remains in the discarding state to
prevent the occurrence of a loop.
• MSTP provides MSTP packet format frequent change guard. If a port receives MSTP packets of different
formats frequently, the MSTP packet format configuration contains errors. If the port is working in MSTP
mode, it will be shut down for protection. Ports disabled in this way can be re-activated after a detection
interval. For more information about the detection interval, see Fundamentals Configuration Guide.
Enabling the output of port state transition information
In a large-scale spanning tree network, you can enable devices to output the port state transition
information of all MSTIs or the specified MSTI in order to monitor the port states in real time.
Follow these steps to enable output of port state transition information:
To do... Use the command... Remarks
Enter system view system-view —
Enable output of port state transition
information (in STP/RSTP mode)
stp port-log instance 0
Enable output of port state transition
information (in PVST mode)
stp port-log vlan vlan-list
Required
Use any command.
Enabled by default.