Bpdu Tunneling Implementation - HP 5820X series Configuration Manual

PAGP
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PVST
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STP
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UDLD
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VTP
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BPDU tunneling implementation

The BPDU tunneling implementations for different protocols are all similar. This section describes how
BPDU tunneling is implemented by taking the STP as an example.
The term STP in this document includes STP, RSTP, and MSTP.
STP calculates the topology of a network by transmitting BPDUs among devices in the network. For more
information, see the chapter "MSTP configuration."
To avoid loops in your network, you can enable STP on your devices. When the topology changes at one
side of the customer network, the devices at this side of the customer network send BPDUs to devices on
the other side of the customer network to ensure 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. As a
result, neither the service provider network nor the customer network can correctly calculate its
independent spanning tree.
To allow each network to calculate an independent spanning tree with STP, BPDU tunneling was
introduced.
BPDU tunneling delivers the following benefits:
BPDUs can be transparently transmitted. BPDUs of the same customer network can be broadcast in a
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specific VLAN across the service provider network, so that the geographically dispersed 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
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service provider network. Each customer network can perform independent spanning tree calculation.
Figure 31 Network diagram for BPDU tunneling implementation
CE 1
User A network 1
As shown in
represents two geographically dispersed segments 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 User A network 1 and User A network 2 to be transparently transmitted
PE 1
ISP network
BPDU tunnel
Figure 31, the upper part is the service provider network (ISP network), and the lower part
PE 2
CE 2
User A network 2
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