H3C Technologies H3C S10500 Series Switches - Manual (Page 102)

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NOTE:
An mCheck operation takes effect on a device that operates in MSTP, RSTP, or PVST mode.
Configuring Digest Snooping
As defined in IEEE 802.1s, connected devices are in the same region only when their MST region-related
configurations (region name, revision level, and VLAN-to-instance mappings) are identical. A spanning
tree device identifies devices in the same MST region by determining the configuration ID in BPDU
packets. The configuration ID includes the region name, revision level, and configuration digest, which is
in 16-byte length and is the result calculated via the HMAC-MD5 algorithm based on VLAN-to-instance
mappings.
Spanning tree implementations vary with vendors, and the configuration digests calculated using private
keys is different, so devices of different vendors in the same MST region cannot communicate with each
other.
To enable communication between an H3C device and a third-party device, enable the Digest Snooping
feature on the port that connects the H3C device to the third-party device in the same MST region.
NOTE:
Before you enable Digest Snooping, ensure that associated devices of different vendors are connected and
run spanning tree protocols.
Configuring the Digest Snooping feature
You can enable Digest Snooping only on the H3C device that is connected to a third-party device that
uses its private key to calculate the configuration digest.
Follow these steps to configure Digest Snooping:
To do... Use the command... Remarks
Enter system view system-view —
Enter Layer 2 Ethernet
interface view or Layer 2
aggregate interface
view
interface interface-type
interface-number
Enter interface
view or port
group view
Enter port group view
port-group manual
port-group-name
Required
Use either command.
Enable Digest Snooping on the interface or
port group
stp config-digest-snooping
Required
Disabled by default.
Return to system view quit —
Enable global Digest Snooping stp config-digest-snooping
Required
Disabled by default.