H3C S3100-52P Operation Manual page 842

Operation Manual – VLAN-VPN
H3C S3100-52P Ethernet Switch
MAC addresses of user packets to the MAC address table of the default VLAN on the
port. However, the port with selective QinQ enabled can insert an outer VLAN tag other
than that of the default VLAN to the packets. Thus, when packets are forwarded from
the service provider to users, they may be broadcast if their destination MAC addresses
cannot be found in the MAC address table of the outer VLANs.
PVID=2
Receives the data that the
private network sends to the
service provider's network
Figure 2-2 Learn MAC addresses of selective QinQ packets
As shown in
The port is configured to receive packets of VLAN 3, tag the received packets with the
outer tag of VLAN 4, and add the source MAC addresses (MAC-A) of the packets to the
MAC address table of its default VLAN (VLAN 2).
When a response packet is returned to the device from VLAN 4 of the service provider
network, the device searches the outbound port for MAC-A in the MAC address table of
VLAN 4. However, because the corresponding entry is not added to the MAC address
table of VLAN 4, this packet is considered to be a unicast packet with unknown
destination MAC address. As a result, this packet will be broadcast to all the ports in
VLAN 4, which wastes the network resources and incurs potential security risks.
The S3100-52P Ethernet switch provide the inter-VLAN MAC address replicating
feature, which can replicate the entries in the MAC address table of the default VLAN to
that of the VLAN corresponding to the outer tag. With the inter-VLAN MAC address
replicating feature enabled, when a device receives a packet from the service provider
network, this device will find the path for the packet by searching the MAC address
table of the VLAN corresponding to the outer tag and unicast the packet. Thus, packet
broadcast is reduced in selective QinQ applications.
Likewise, the entries in the MAC address table of the outer VLAN can also be replicated
to that of the default VLAN on a port, through which the outbound port to the service
provider network can be determined through the MAC address table of the default
VLAN and user packets destined for the service provider can be unicast.
Public Public
Network
Network
VLAN4
MAC-A
PVID=2
VLAN3
MAC-A
Private Private
Network Network
Receives the data that the
service provider's network
sends to the private network
Figure 2-2, the default VLAN of the port used to receive packets is VLAN 2.
Chapter 2 Selective QinQ Configuration
VLAN4
MAC-A
2-3