Configuring Bpdu Tunneling; Configuration Prerequisites - 3Com 4510G Configuration Manual

networks of the same customer can implement consistent spanning tree calculation across the
service provider network.
BPDUs of different customer networks can be confined within different VLANs for transmission on
the service provider network. Thus, each customer network can perform independent spanning
tree calculation.
Figure 11-2 Network diagram for BPDU tunneling implementation
CE 1
User A network 1
As shown in Figure
part represents two different parts of a customer network: User A network 1 and User A network 2.
Enabling the BPDU tunneling function on the edge devices (PE 1 and PE 2) in the service provider
network allows BPDUs of the customer network to be transparently transmitted in the service provider
network, thus ensuring consistent spanning tree calculation of User A network, without affecting the
spanning tree calculation of the service provider network.
Assume a BPDU is sent from User A network 1 to User A network 2:
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.
At the egress of the service provider network, PE 2 recognizes the BPDU with the destination
MAC address
0x0180-C200-0000, and then sends the BPDU to User A network 2.
Make sure, through configuration, that the VLAN tags carried in BPDUs are neither changed nor
removed during the transparent transmission in the service provider network; otherwise, the devices in
the service provider network will fail to transparently transmit the customer network BPDUs correctly.

Configuring BPDU Tunneling

Configuration Prerequisites

Before configuring BPDU tunneling for a protocol, enable the protocol in the customer network
first.
PE 1
ISP network
BPDU tunnel
11-2, the upper part is the service provider network (ISP network), and the lower
0x010F-E200-0003,
PE 2
CE 2
User A network 2
restores its original
11-3
destination MAC address