Operation Manual – QinQ-BPDU TUNNEL
H3C S5500-SI Series Ethernet Switches Chapter 2 BPDU Tunneling Configuration
2-1
Chapter 2 BPDU Tunneling Configuration
When configuring BPDU tunneling, go to these sections for information you are
interested in:
zIntroduction to BPDU Tunneling
zConfiguring BPDU Isolation
zConfiguring BPDU Transparent Transmission
zConfiguring Destination Multicast MAC Address for BPDU Tunnel Frames
zBPDU Tunneling Configuration Example
2.1 Introduction to BPDU Tunneling
2.1.1 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.
zBPDU tunneling can isolate BPDUs of different customer networks, so that one
network is not affected by others while calculating the topological structure.
zBPDU 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.
2.1.2 How BPDU Tunneling Works
The BPDU tunneling implements the following two functions:
zBPDU isolation
zBPDU transparent transmission
The work process of IGMP is as follows:
I. 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.
