3Com Switch 8800 Advanced Software V5 Configuration Guide

Configuring Digest Snooping 127
Configuration Procedure Follow these steps to configure Digest Snooping:
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CAUTION:
■ You can only enable the Digest Snooping feature on the device connected to
another vendor’s device that use private key to compute the configuration
digest.
■ With the Digest Snooping feature enabled, comparison of configuration digest
is not needed for in-the-same-region check, so the VLAN-to-instance mappings
must be the same on associated ports.
■ With global Digest Snooping enabled, modification of VLAN-to-instance
mappings and removing of the current region configuration using the undo
stp region-configuration command are not allowed. You can only modify
the region name and revision level.
■ You need to enable this feature both globally and on associated ports to make
it take effect. It is recommended to enable the feature on all associated ports
first and then globally, making all configured ports take effect, and disable the
feature globally to disable it on all associated ports.
■ It is not recommended to enable Digest Snooping on the MST region edge port
to avoid loops.
■ Do not enable Digest Snooping when the network works well to avoid traffic
interruption.
Configuration Examples Network requirements
■ Switch A and Switch B connect to a third-party’s device and all the devices are
in the same region.
■ Enable Digest Snooping on Switch A and Switch B so that the three devices can
communicate with one another.
To do... Use the command... Remarks
Enter system view system-view -
Enter Ethernet
interface or
port group
view
Enter Ethernet
interface view
interface interface-type
interface-number
Choose either
Enter port
group view
port-group { manual
port-group-name |
aggregation agg-id }
Enable digest snooping on the
interface or port group
stp config-digest-snooping Required
Not enabled by default
Return to system view quit -
Enable global digest snooping stp config-digest-snooping Required
Not enabled by default