Huawei Quidway S8500 Series - Page 863

Command Manual – STP
Quidway S8500 Series Routing Switches Chapter 2 Digest Snooping Configuration Commands
Huawei Technologies Proprietary
2-1
Chapter 2 Digest Snooping Configuration
Commands
2.1 Digest Snooping Configuration Commands
2.1.1 stp config-digest-snooping
Syntax
stp config-digest-snooping
undo stp config-digest-snooping
View
System view, Ethernet port view
Parameter
None
Description
Use the stp config-digest-snooping command to enable digest snooping.
Use the undo stp config-digest-snooping command to disable digest snooping.
Digest snooping is disabled by default.
According to IEEE 802.1s, two connected switches can communicate with each other
through multiple spanning tree instances (MSTIs) in a multiple spanning tree protocol
(MSTP) domain only when they are configured with the same domain settings. With
MSTP employed, interconnected switches determine whether or not they are in the
same domain by checking the configuration IDs of the bridge protocol data units
(BPDUs) between them. (A configuration ID comprises information such as domain ID,
configuration digest.)
As switches of some manufacturers come with some proprietary protocols concerning
spanning trees employed, a switch of this type cannot communicate with other switches
in an MSTP domain even if it is configured with the same domain settings as other
switches in the MSTP domain.
This kind of problems can be overcome by implementing digest snooping. Digest
snooping enables a switch to track and maintain configuration digests of other switches
that are in the same domain and come from other manufacturers by examining their
BPDUs. It also enables the switch to insert corresponding configuration digests in its