H3C Technologies H3C S3100 Series Switches - Manual (Page 851)

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BPDU Tunnel Configuration
This chapter is only applicable to S3100-EI series switches.
When configuring BPDU tunnel, go to these sections for information you are interested in:
z BPDU Tunnel Overview
z BPDU Tunnel Configuration
z Displaying and Maintaining BPDU Tunnel Configuration
z BPDU Tunnel Configuration Example
BPDU Tunnel Overview
Introduction to the BPDU Tunnel Feature
Normally, Layer 2 protocols are needed in a LAN for network topology maintenance and management.
For example, spanning tree protocol (STP) is used for maintaining spanning trees and preventing loops.
Huawei group management protocol (HGMP) is used for managing network topology and devices in a
network.
When multiple branch networks of an organization are connected together through a public network,
you can combine the corresponding network nodes into one so as to maintain the branch networks as a
whole. This requires the packets of some of the user’s Layer 2 protocol packets be transmitted across
the provider’s network without getting involved in the computation of the public network.
The BPDU Tunnel feature is designed to address the above requirements. It enables some Layer 2
protocol packets of private networks to be transmitted along tunnels established in the public network.
BPDU Tunnel Fundamental
Layer 2 protocol packet identification
Different from the processing of data packets, a Layer 2 protocol packet is classified first when it
reaches a network device. A Layer 2 protocol packet conforming to IEEE standards carries a special
destination MAC address (for example, the destination MAC address of an STP protocol packet is
0180-c200-0000) and contains a type field. Some proprietary protocols adopt the same packet structure,
where a private MAC address is used to identify the corresponding proprietary protocol, and the type
field is used to identify the specific protocol type.
Transmitting BPDU packets transparently
As shown in Figure 3-1 , the network on the top is the service provider network, and the one on the
bottom is a customer network. The service provider network contains edge devices connecting the