H3C Technologies H3C WX3000E Series Wireless Switches - Manual (Page 80)

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• GigabitEthernet 1/0/1 on Device A and GigabitEthernet 1/0/1 on Device B allow the traffic of
VLAN 1 to pass through. GigabitEthernet 1/0/2 on Device A and GigabitEthernet 1/0/2 on
Device B allow the traffic of VLAN 2 to pass through.
• Device A is the root bridge, and Device A and Device B both run a spanning tree protocol.
GigabitEthernet 1/0/2 on Device B is blocked, causing traffic of VLAN 2 to be blocked.
• Configure VLAN Ignore to keep GigabitEthernet 1/0/2 of Device B in the forwarding state.
Figure 17 VLAN Ignore configuration
2. Configuration procedure
# Enable VLAN Ignore for VLAN 2 on Device B.
system-view
[DeviceB] stp ignored vlan 2
# Display the VLAN Ignore-enabled VLAN.
[DeviceB] display stp ignored-vlan
STP-Ignored VLAN: 2
Configuring Digest Snooping
As defined in IEEE 802.1s, interconnected 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 checking the configuration
ID in BPDU packets. The configuration ID includes the region name, revision level, and configuration
digest that 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 connecting the H3C device to the third-party device in the same MST region.
NOTE:
Before enabling 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.