Huawei Quidway S7700 Configuration Manual - Ethernet page 592

Quidway S7700 Smart Routing Switch
Configuration Guide - Ethernet
A PE generally functions as an aggregation device. As shown in
interface on PE1 can receive BPDUs from LAN-A and LAN-B. To differentiate BPDUs from
the two LANs, BPDUs sent from CEs to PEs must have VLAN tags. In
sent from LAN-A contain VLAN 200 and packets sent from LAN-B contain VLAN 100.
Packets of certain Layer 2 protocols such as STP, RSTP, and MSTP are untagged. When
receiving Layer 2 protocol packets with VLAN tags, PEs consider the packets invalid and discard
them. In this case, you can configure VLAN-based Layer 2 protocol transparent transmission
on PEs so that Layer 2 protocol packets can traverse the backbone network through Layer 2
tunnels.
Similar to interface-based Layer 2 protocol transparent transmission, you can use either of the
following methods to implement VLAN-based Layer 2 protocol transparent transmission:
l
l
Issue 01 (2011-07-15)
Replace the default multicast MAC address of the Layer 2 protocol that can be identified
by PEs with another multicast MAC address.
1. Configure all PEs as providers. Then the multicast destination MAC address of
BPDUs sent from the backbone network is changed from 01-80-C2-00-00-00 to
01-80-C2-00-00-08.
2. Configure all devices on user networks as customers. Then the multicast destination
MAC address of BPDUs sent from user networks is 01-80-C2-00-00-00.
3. Configure devices on user networks to send Layer 2 protocol packets with the specified
VLAN IDs to the backbone network.
4. Enable PEs to identify Layer 2 protocol packets with the specified VLAN IDs and
allow these packets to pass.
5. PEs (providers) do not consider these packets as Layer 2 protocol BPDUs and do not
send them to the CPU. Instead, PEs select a Layer 2 tunnel to forward the packets
according to the default VLANs of interfaces.
6. Internal nodes on the backbone network forward the packets across the backbone
network as common Layer 2 packets.
7. The egress device on the backbone network forwards the packets to user networks
without modifying the packets.
NOTE
l This method is applicable only to STP, RSTP, and MSTP. To configure a device as the provider,
run the bpdu-tunnel stp bridge role provider command.
Replace the original multicast MAC address of Layer 2 protocol packets from user networks
with a specified multicast MAC address.
NOTE
This method is applicable to all Layer 2 protocols.
1. Configure devices on user networks to send Layer 2 protocol packets with the specified
VLAN IDs to the backbone network.
2. Enable PEs to identify Layer 2 protocol packets with the specified VLAN IDs and
allow these packets to pass.
3. PEs replace the standard multicast destination MAC address of Layer 2 protocol
packets with a specified multicast MAC address according to the mappings between
multicast destination MAC addresses and Layer 2 protocols.
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11 Layer 2 Protocol Transparent Transmission Configuration
Figure 11-3, the aggregation
Figure 11-3, packets
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