3Com Switch 8800 Configuration Guide Chapter 38 MSTP Region-configuration
38-29
By default, the parameter is configured as auto.
38.2.15 Configuring the mCheck Variable of a Port The port of an MSTP switch operates in either STP-compatible or MSTP mode.
Suppose a port of an MSTP switch on a switching network is connected to an STP
switch, the port will automatically transit to operate in STP-compatible mode. However,
the port stays in STP-compatible mode and cannot automatically transit back to MSTP
mode when the STP switch is removed. In this case, you can perform mCheck
operation to transit the port to MSTP mode by force.
You can use the following measure to perform mCheck operation on a port.
I. Configuration in system view
Perform the following configuration in system view.
Table 38-24 Configure the mCheck variable of a port
Operation Command
Perform mCheck operation on a port. stp interface interface-list mcheck
Note:
By default, MSTP runs in MSTP mode, which is compatible with RSTP and STP (This
mode can recognize MSTP BPDU, STP config BPDU and RSTP config BPDU).
However, the STP switch can only recognize config BPDU (STP BPDU) sent by the
STP and RSTP bridges. After the switch running STP-compatible mode switches back
to MSTP mode, it will not send MSTP BPDU if you do not execute the stp mcheck
command. Therefore, the connected device still sends config BPDU (STP BPDU) to it,
causing the same configuration exists in different regions and other problems.
Remember to perform stp interface mcheck after modifying stp mode.
II. Configuration in Ethernet port view
Perform the following configuration in Ethernet port view.
Table 38-25 Configure the mCheck variable of a port
Operation Command
Perform mCheck operation on a port. stp mcheck