Figure 9-2 Transparent Transmission Of Bpdus On The Isp Network - Huawei Quidway S9300 Configuration Manual

Quidway S9300 Terabit Routing Switch
Configuration Guide - Ethernet
Table 9-1 Description of fields in BPDUs
Field Name
Destination
address
Source address
Length
Background of the BPDU Tunnel
As shown in
1 are required to traverse the ISP network to reach user network 2 so that the spanning tree can
be calculated. All the BPDUs use a fixed destination MAC address. Therefore, when BPDUs of
user network 1 reaches PE1 of the ISP network, PE1 cannot identify the network from which
the BPDUs are sent. PE1 sends the BPDUs to the CPU, and the CPU calculates the spanning
tree.
In this case, only the devices of user network 1 and PE1 are involved in calculation of the
spanning tree, and devices of user network 2 are not involved. Therefore, BPDUs of user network
1 may not be forwarded to user network 2.

Figure 9-2 Transparent transmission of BPDUs on the ISP network

To ensure that the BPDUs of user network 1 can reach user network 2, enable BPDUs to be
transparently transmitted on the ISP network. To enable BPDUs to be transparently transmitted
on the ISP network, make sure that:
l
l
l
The BPDU tunnel is the path that transparently transmits BPDUs on the packet switched network
(PSN).
Issue 03 (2009-08-20)
Length
48 bits
48 bits
16 bits
Figure 9-2, user network 1 and user network 2 run MSTP. BPDUs of user network
PE1
CE1
User
network
1
All the branches of a user network can receive the BPDUs from the user network.
BPDUs of a user network cannot be processed by the CPUs on the ISP network.
BPDUs of one user network do not affect BPDUs of other user networks.
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Description
Destination MAC address of a BPDU. For a user, this field
is fixed to 0180-C200-0000.
Source MAC address of a BPDU.
Length of data in the BPDU.
ISP
network
PE2
CE2
9 BPDU Tunnel Configuration
User
network
2
9-3