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not match the configured format, we set the state of the port which receives the
unmatched packet to DISCARDING to prevent both sides consider themselves the root
which leads to circuits.
When the AUTO format is set, and over one equipment which is not compatible with
each other are connected on the port (e.g. a equipment running through a HUB or
Transparent Transmission BPDU is connected with several equipments running MSTP),
the format alter counts will be recorded and the port will be disabled at certain count
threshold. The port can only be re-enabled by the administrator.
Example: Configure port message format as the message format of IEEE.
Switch(config)#interface ethernet 1/2
Switch(Config-If-Ethernet1/2)#spanning-tree format standard
Switch(Config-If-Ethernet1/2)#
12.1.22 spanning-tree digest-snooping
Command: spanning-tree digest-snooping
no spanning-tree digest-snooping
Function: Configure the port to use the authentication string of partner port; the command
―no spanning-tree digest-snooping‖ restores to use the port generated authentication
string.
Parameter: None
Command mode: Port Mode
Default: Don‘t use the authentication string of partner port.
Usage Guide: According to MSTP protocol, the region authentication string is generated
by MD5 algorithm with public authentication key, intstance ID, VLAN ID. Some
manufactory don‘t use the public authentication key, this causes the incompatibility. After
the command is executed the port can use the authentication string of partner port, realize
compatibility with these manufactories equipment.
Note: Because the authentication string is related to instance ID and VLAN ID, the
command may cause recognizing the equipment that with different instance and VLAN
relation as in the same region. Before the command is executed, make sure that instance
and VLAN relation is accord for all the equipment. If there are more than one equipment
connected, all the connected ports should execute this command.
Example: Configure the authentication string of partner port.
Switch(config)#interface ethernet 1/2
Switch(Config-If-Ethernet1/2)#spanning-tree digest-snooping
Switch(Config-If-Ethernet1/2)#
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