H3C Technologies H3C WX5500E Series Access Controllers - Manual (Page 114)

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• CDP
• DLDP
• EOAM
• GVRP
• HGMP
• LACP
• LLDP
• PAGP
• PVST
• STP
• UDLD
• VTP
BPDU tunneling implementation
The BPDU tunneling implementations for different protocols are all similar. This section uses STP to
describe how to implement BPDU tunneling. This document uses the term "STP" in a broad sense. It
includes STP, RSTP, and MSTP.
STP calculates the topology of a network by transmitting BPDUs among devices in the network. For more
information, see "Configuring spanning tree protocols."
To avoid loops in your network, you can enable STP on your devices. When the topology changes at one
side of the customer network, devices at that side of the customer network send BPDUs to devices on the
other side of the customer network. This ensures consistent spanning tree calculation in the entire
customer network. However, because BPDUs are Layer 2 multicast frames, all STP-enabled devices, both
in the customer network and in the service provider network, can receive and process these BPDUs. In this
case, neither the service provider network nor the customer network can correctly calculate its
independent spanning tree.
BPDU tunneling allows each network to calculate an independent spanning tree with STP.
BPDU tunneling delivers the following benefits:
• BPDUs can be transparently transmitted. BPDUs of one customer network can be broadcast in a
specific VLAN across the service provider network, allowing that customer's geographically
dispersed networks to 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. This enables each customer network to perform independent
spanning tree calculations.