H3C S7500 Series Ethernet Switches Command Manual

Command Manual – MSTP
H3C S7500 Series Ethernet Switches Chapter 1
MSTP Configuration Commands
1-12
1.1.12 stp config-digest-snooping
Syntax
stp config-digest-snooping
undo stp config-digest-snooping
View
System view
Parameters
None
Description
Use the stp config-digest-snooping command to enable the digest snooping
function.
Use the undo stp config-digest-snooping command to disable the digest snooping
function.
The digest snooping function is disabled by default.
According to IEEE 802.1s, two connected switches can interwork with each other
through MSTIs in an MST region only when the two switches have the same MST
region-related configuration. With MSTP employed, interconnected switches determine
whether or not they are in the same MST region by checking the configuration IDs of
the BPDUs between them. (A configuration ID contains information such as region ID
and configuration digest.)
As some other vendors' switches adopt proprietary spanning tree protocols, they
cannot interwork with other switches in an MST region even if they are configured with
the same MST region-related settings as other switches in the MST region.
This kind of problems can be overcome by implementing the digest snooping function.
If a switch port is connected to another vendor's switch that has the same MST
region-related settings but adopts a proprietary spanning tree protocol, you can enable
digest snooping on the port. Then the switch regards the peer switch connected to the
port as in the same region and records the configuration digests carried in the BPDUs
received from the switch, which will be put in the BPDUs to be sent to the peer switch.
In this way, the switch can interwork with other vendors’ switches in an MST region.