H3C Technologies H3C S3600 Series Switches - Manual (Page 1030)

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VLAN-VPN Configuration
When configuring VLAN-VPN, go to these sections for information you are interested in:
z VLAN-VPN Overview
z VLAN-VPN Configuration
z Displaying and Maintaining VLAN-VPN Configuration
z VLAN-VPN Configuration Example
The function of transparent IGMP message transmission on a VLAN-VPN port is added. For more
information, refer to Enabling Transparent IGMP Message Transmission on a VLAN-VPN Port .
VLAN-VPN Overview
Introduction to VLAN-VPN
Virtual private network (VPN) is a new technology that emerges with the expansion of the Internet. It can
be used for establishing private networks over the public network. With VPN, you can specify to process
packets on the client or the access end of the service provider in specific ways, establish dedicated
tunnels for user traffic on public network devices, and thus improve data security.
VLAN-VPN feature is a simple yet flexible Layer 2 tunneling technology. It tags private network packets
with outer VLAN tags, thus enabling the packets to be transmitted through the service providers’
backbone networks with both inner and outer VLAN tags. In public networks, packets of this type are
transmitted by their outer VLAN tags (that is, the VLAN tags of public networks), and the inner VLAN
tags are treated as part of the payload.
Figure 1-1 shows the structure of single-tagged and double-tagged Ethernet frames.
Figure 1-1 Single-tagged frame structure vs. double-tagged Ethernet frame structure
Compared with MPLS-based Layer 2 VPN, VLAN-VPN has the following features: