4-30
By then, you can perform an mCheck operation to force the port to migrate to the MSTP (or RSTP)
mode.
You can perform mCheck on a port through the following two approaches, which lead to the same
result.
Performing mCheck globally
Follow these steps to perform global mCheck:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Perform mCheck
stp mcheck
Required
Performing mCheck in interface view
Follow these steps to perform mCheck in interface view:
To do...
Use the command...
Remarks
Enter system view
system-view
—
Enter Ethernet interface view, or Layer
2 aggregate interface view
interface interface-type
interface-number
—
Perform mCheck
stp mcheck
Required
An mCheck operation takes effect on a device only when MSTP operates in RSTP or MSTP mode.
Configuring Digest Snooping
As defined in IEEE 802.1s, interconnected devices are in the same region only when the MST
region-related configurations (domain name, revision level, VLAN-to-instance mappings) on them are
identical. An MSTP-enabled device identifies devices in the same MST region by checking the
configuration ID in BPDU packets. The configuration ID includes the region name, revision level,
configuration digest that is in 16-byte length and is the result calculated via the HMAC-MD5 algorithm
based on VLAN-to-instance mappings.
Since MSTP implementations vary with vendors, the configuration digests calculated using private
keys is different; hence different vendors’ devices in the same MST region can not communicate with
each other.
Enabling the Digest Snooping feature on the port connecting the local device to a third-party device in
the same MST region can make the two devices communicate with each other.
