242
uses max-hop to count BPDU lifetime. The max-hop is degressive in the network. The
BPDU has the max value when it initiates from MSTI root bridge. Once the BPDU is
received, the value of the max-hop is reduced by 1. When a port receives the BPDU with
max-hop as 0, it drops this BPDU and sets itself as designated port to send the BPDU.
Example:
Set max hop to 32.
Switch(Config)#spanning-tree max-hop 32
8.3.13 spanning-tree mcheck
Command: spanning-tree mcheck
Function:
Force the port to run in the MSTP mode.
Command mode:
Interface Mode
Default:
The port is in the MSTP mode by default.
Usage Guide:
If a network which is attached to the current port is running IEEE 802.1D
STP, the port converts itself to run in STP mode. The command is used to force the port
to run in the MSTP mode. But once the port receives STP messages, it changes to work
in the STP mode again.
This command can only be used when the switch is running in IEEE802.1s MSTP
mode. If the switch is running in IEEE802.1D STP mode, this command is invalid.
Example:
Force the port 1/2 to run in the MSTP mode.
Switch(Config-Ethernet1/2)#spanning-tree mcheck
8.3.14 spanning-tree mode
Command: spanning-tree mode {mstp|stp}
no spanning-tree mode
Function:
Set the spanning-tree mode in the switch; The command “
no spanning-tree
mode
” restores the default setting.
Parameter: mstp
sets the switch in IEEE802.1s MSTP mode;
stp
sets the switch in
IEEE802.1D STP mode.
Command mode:
Global Mode
Default:
The switch is in the MSTP mode by default.
Usage Guide:
When the switch is in IEEE802.1D STP mode, it only sends standard
IEEE802.1D BPDU and TCN BPDU. It drops any MSTP BPDUs.
Example:
Set the switch in the STP mode.
Switch(Config)#spanning-tree mode stp
8.3.15 spanning-tree mst configuration
