102• Ethernet Operation, Administration and Maintenance (EOAM)• GARP VLAN Registration Protocol (GVRP)• HW Group Management Protocol (HGMP)• Link Aggregation Control Protocol (LACP)• Link Layer Discovery Protocol (LLDP)• Port Aggregation Protocol (PAGP)• Per VLAN Spanning Tree (PVST)• Spanning Tree Protocol (STP)• Unidirectional Link Direction (UDLD)• VLAN Trunking Protocol (VTP)BPDU tunneling implementationThe BPDU tunneling implementations for different protocols are all similar. This section uses the SpanningTree Protocol (STP) as an example to describe how to implement BPDU tunneling.NOTE:• 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 moreinformation, see the chapter “Spanning tree configuration.”To avoid loops in your network, you can enable STP on your devices. When the topology changes at oneside of the customer network, devices at that side of the customer network send BPDUs to devices on theother side of the customer network to ensure consistent spanning tree calculation in the entire customernetwork. However, because BPDUs are Layer 2 multicast frames, all STP-enabled devices, both in thecustomer 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 independentspanning 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 aspecific VLAN across the service provider network, allowing that customer’s geographicallydispersed networks to implement consistent spanning tree calculation across the service providernetwork.• BPDUs of different customer networks can be confined within different VLANs for transmission onthe service provider network. This enables each customer network to perform independentspanning tree calculation.
