84
Figure 23 TC snooping application scenario
In the network, Device transparently transmits the received BPDUs and does not participate in
spanning tree calculations. When a topology change occurs to user networks, Device may need a
long time to learn the correct MAC address table entries and ARP entries, resulting in long network
disruption. To avoid the network disruption, you can enable TC snooping on Device.
With TC snooping enabled, a device actively updates the MAC address table entries and ARP
entries upon receiving TC-BPDUs, so that the device can normally forward the user traffic.
For more information about MAC address table entries, see "Configuring the MAC address table."
For more information about ARP, see
Layer 3—IP Services Configuration Guide
.
Configuration restrictions and guidelines
•
TC snooping and STP are mutually exclusive. You must globally disable the spanning tree
feature before enable TC snooping.
•
TC snooping does not take effect on the ports on which BPDU tunneling is enabled for spanning
tree protocols. For more information about BPDU tunneling, see "Configuring BPDU tunneling."
•
TC snooping does not support PVST TC-BPDUs. As a result, TC snooping does not take effect
in a PVST network.
Configuration procedure
To configure TC snooping:
Step Command
Description
1.
Enter system view.
system-view
N/A
2.
Globally disable the
spanning tree feature.
undo stp enable
By default, the spanning tree
feature is disabled globally.
3.
Enable TC snooping.
stp tc-snooping
Disabled by default.
Configuring protection functions
A spanning tree device supports the following protection functions:
User network 1
User network 2
Device