Enabling The Output Of Port State Transition Information - 3Com 4500G Family Configuration Manual

dot1s: 802.1s-compliant standard format, and
legacy: Compatible format
By default, the packet format recognition mode of a port is auto, namely the port automatically
distinguishes the two MSTP packet formats, and determines the format of packets it will send based on
the recognized format. You can configure the MSTP packet format on a port. After the configuration,
when working in MSTP mode, the port sends and receives only MSTP packets of the format you have
configured to communicate with devices that send packets of the same format.
Make this configuration on the root bridge and on the leaf nodes separately.
Follow these steps to configure the MSTP packet format to be supported on a port or a group of ports:
To do...
Enter system view
Enter Ethernet
Enter
interface view, or
interface
Layer 2 aggregate
view or
interface view
port group
Enter port group
view
view
Configure the mode the port
uses to recognize/send MSTP
packets
MSTP provides the MSTP packet format incompatibility guard function. In MSTP mode, if a port is
configured to recognize/send MSTP packets in a mode other than auto, and receives a packet in a
format different from the specified type, the port will become a designated port and remain in the
discarding state to prevent the occurrence of a loop.
MSTP provides the MSTP packet format frequent change guard function. If a port receives MSTP
packets of different formats frequently, this means that the MSTP packet format configuration
contains errors. In this case, if the port is working in MSTP mode, it will be disabled for protection.
Those ports closed thereby can be restored only by the network administrators.

Enabling the Output of Port State Transition Information

In a large-scale, MSTP-enabled network, there are a large number of MSTIs, so ports may frequently
transition from one state to another. In this situation, you can enable devices to output the port state
transition information of all MSTIs or the specified MSTI so as to monitor the port states in real time.
Make this configuration on the root bridge and on the leaf nodes separately.
Follow these steps to enable output of port state transition information:
To do...
Enter system view
Use the command...
system-view
interface interface-type
interface-number
port-group manual
port-group-name
stp compliance { auto | dot1s |
legacy }
Use the command...
system-view
1-28
Remarks
—
Required
Use either command.
Required
auto by default
Remarks
—