L2Pt Operating Mechanism - H3C S6850 Series Configuration Manual

•
LLDP.
•
MVRP.
•
PAgP.
•
PVST.
•
STP (including STP, RSTP, and MSTP).
•
UDLD.
•
VTP.

L2PT operating mechanism

As shown in
•
When a port of PE 1 receives a Layer 2 protocol packet from the customer network in a VLAN,
it performs the following operations:
Multicasts the packet out of all customer-facing ports in the VLAN except the receiving port.
Encapsulates the packet with a specified destination multicast address, and multicasts it
out of all ISP-facing ports in the VLAN. The encapsulated packet is called the BPDU
tunneled packet.
•
When a port of PE 2 in the VLAN receives the tunneled packet from the service provider
network, it performs the following operations:
Multicasts the packet out of all ISP-facing ports in the VLAN except the receiving port.
Decapsulates the packet and multicasts the decapsulated packet out of all customer-facing
ports in the VLAN.
Figure 2 L2PT operating mechanism
Customer
network
For example, as shown in
network 2. CEs are the edge devices on the customer network, and PEs are the edge devices on
the service provider network. L2PT processes the packet as follows:
1. PE 1 performs the following operations:
a. Encapsulates the packet with a specified destination multicast MAC address
(010f-e200-0003 by default).
b. Sends the tunneled packet out of all ISP-facing ports in the packet's VLAN.
2. Upon receiving the tunneled packet, PE 2 decapsulates the packet and sends the BPDU to CE
2.
Through L2PT, both the ISP network and Customer A's network can perform independent spanning
tree calculations.
Figure 2, L2PT operates as follows:
PE 1
Figure
Service provider network
Layer 2 protocol packets
from customer networks
Tunneled packets
3, PE 1 receives an STP packet (BPDU) from network 1 to
2
Customer
network
PE 2