H3C Technologies H3C WX6000 Series Access Controllers - Manual (Page 108)

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BPDU Tunneling Configuration
When configuring BPDU tunneling, go to these sections for information you are interested in:
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Introduction to BPDU Tunneling
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Configuring BPDU Isolation
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Configuring BPDU Transparent Transmission
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Configuring Destination Multicast MAC Address for BPDU Tunnel Frames
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BPDU Tunneling Configuration Example
Introduction to BPDU Tunneling
Why BPDU Tunneling
To avoid loops in your network, you can enable the spanning tree protocol (STP) on your device.
However, STP gets aware of the topological structure of a network by means of bridge protocol data
units (BPDUs) exchanged between different devices and the BPDUs are Layer 2 multicast packets,
which can be received and processed by all STP-enabled devices on the network. This prevents each
network from correctly calculating its spanning tree. As a result, when redundant links exist in a network,
data loops will unavoidably occur.
By allowing each network to have its own spanning tree while running STP, BPDU tunneling can resolve
this problem.
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BPDU tunneling can isolate BPDUs of different customer networks, so that one network is not
affected by others while calculating the topological structure.
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BPDU tunneling enables BPDUs of the same customer network to be broadcast in a specific VLAN
in the provider network, so that the geographically dispersed customer networks of the same
customer can implement consistent spanning tree calculation across the provider network.
How BPDU Tunneling Works
The BPDU tunneling implements the following two functions:
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BPDU isolation
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BPDU transparent transmission
The work process of IGMP is as follows:
BPDU isolation
When a port receives BPDUs of other networks, the port will discard the BPDUs, so that they will not
take part in spanning tree calculation. Refer to
Configuring BPDU Isolation .
BPDU transparent transmission
As shown in Figure 13-1 , the upper part is the service provider network, and the lower part represents
the customer networks. The customer networks include network A and network B. Enabling the BPDU
tunneling function on the BPDU input/output devices across the service provider network allows BPDUs
of the customer networks to be transparently transmitted in the service provider network, and allows