Bpdu Tunneling Configuration; Introduction To Bpdu Tunneling; Background - 3Com 4510G Configuration Manual

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BPDU Tunneling Configuration

When configuring BPDU tunneling, go to these sections for information you are interested in:

Introduction to BPDU Tunneling

Configuring BPDU Tunneling
BPDU Tunneling Configuration Examples
Introduction to BPDU Tunneling
As a Layer 2 tunneling technology, BPDU tunneling enables Layer 2 protocol packets from
geographically dispersed customer networks to be transparently transmitted over specific channels
across a service provider network.

Background

Customers usually use dedicated lines in a service provider network to build their own Layer 2
networks. As a result, very often, a customer network is broken down into parts located at different
sides of the service provider network. As shown in
both of which belong to VLAN 100. User A's network is divided into network 1 and network 2, which are
connected by the service provider network. When Layer 2 protocol packets cannot be transparently
transmitted in the service provider network, User A's network cannot implement independent Layer 2
protocol calculation (for example, STP spanning tree calculation). In this case, the Layer 2 protocol
calculation in User A's network is mixed with that in the service provider network.
Figure 11-1 BPDU tunneling application scenario
CE 1
User A network 1
VLAN 100
With BPDU tunneling, Layer 2 protocol packets from customer networks can be transparently
transmitted in the service provider network:
2) After receiving a Layer 2 protocol packet from User A network 1, PE 1 in the service provider
network encapsulates the packet, replaces its destination MAC address with a specific multicast
MAC address, and then forwards the packet in the service provider network;
3) The encapsulated Layer 2 protocol packet (called bridge protocol data unit, BPDU) is forwarded to
PE 2 at the other end of the service provider network, which decapsulates the packet, restores the
original destination MAC address of the packet, and then sends the packet to User A network 2.
PE 1
ISP network
11-1
Figure 11-1, User A has two devices: CE 1 and CE 2,
PE 2
CE 2
User A network 2
VLAN 100