H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 115)

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Figure 29 BPDU tunneling implementation
The upper section of Figure 29 represents the service provider network (ISP network). The lower section,
including User A network 1 and User A network 2, represents customer networks. Enabling BPDU
tunneling on edge devices (PE 1 and PE 2) in the service provider network allows BPDUs of User A
network 1 and User A network 2 to be transparently transmitted through the service provider network.
This ensures consistent spanning tree calculation throughout User A network, without affecting the
spanning tree calculation of the service provider network.
Assume that a BPDU is sent from User A network 1 to User A network 2:
1. At the ingress of the service provider network, PE 1 changes the destination MAC address of the
BPDU from 0x0180-C200-0000 to a special multicast MAC address, 0x010F-E200-0003 (the
default multicast MAC address), for example. In the service provider network, the modified BPDU
is forwarded as a data packet in the VLAN assigned to User A.
2. At the egress of the service provider network, PE 2 recognizes the BPDU with the destination MAC
address 0x010F-E200-0003, restores its original destination MAC address 0x0180-C200-0000,
and then sends the BPDU to CE 2.
NOTE:
Make sure, through configuration, the VLAN tags carried in BPDUs are neither changed nor removed
during transparent transmission in the service provider network. Otherwise, devices in the service provider
network will fail to transparently transmit the customer network BPDUs correctly.
Configuration prerequisites
Before configuring BPDU tunneling for a protocol, perform the following tasks:
• Enable the protocol in the customer network.
• Assign the port on which you want to enable BPDU tunneling on the PE device and the connected
port on the CE device to the same VLAN.
• Configure ports that connect network devices in the service provider network as trunk ports that
allow packets of any VLAN to pass through.
Configuration restrictions and guidelines
• You can enable BPDU tunneling for different protocols in different views. Settings made in Layer 2
Ethernet interface view or Layer 2 aggregate interface view take effect only on the current port.
Settings made in port group view take effect on all ports in the port group.