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Operation Manual – VLAN VPN
Quidway S5600 Series Ethernet Switches-Release 1510
Chapter 1 VLAN-VPN Configuration
Huawei Technologies Proprietary
1-1
Chapter 1 VLAN-VPN Configuration
1.1 VLAN-VPN Overview
1.1.1 Introduction to VLAN-VPN
The VLAN-VPN function enables packets to be transmitted across the operators’
backbone networks with VLAN tags of private networks encapsulated in those of public
networks. In public networks, packets of this type are transmitted by their outer VLAN
tags (that is, the VLAN tags of public networks). And those of private networks which
are encapsulated in the VLAN tags of public networks are shielded.
Figure 1-1 describes the structure of the packets with single-layer VLAN tags.
ETYPE(8100)
(2B)
DA
(6B)
SA
(6B)
User VLAN TAG
(2B)
ETYPE
(2B)
DATA
(0-1500B)
FCS
(4B)
Figure 1-1
Structure of packets with single-layer VLAN tags
Figure 1-2 describes the structure of the packets with nested VLAN tags.
FCS
(4B)
DA
SA
ETYPE
Nested VLAN TAG
ETYPE
User VLAN TAG ETYPE
DATA
(0~1500B)
(2B)
(2B)
(2B)
(2B)
(2B)
(6B)
(6B)
FCS
(4B)
DA
SA
ETYPE
Nested VLAN TAG
ETYPE
User VLAN TAG ETYPE
DATA
(0~1500B)
(2B)
(2B)
(2B)
(2B)
(2B)
(6B)
(6B)
DA
SA
ETYPE
Nested VLAN TAG
ETYPE
User VLAN TAG ETYPE
DATA
(0~1500B)
(2B)
(2B)
(2B)
(2B)
(2B)
(6B)
(6B)
Figure 1-2
Structure of packets with double-layer VLAN tags
Compared with MPLS-based Layer 2 VPN, VLAN-VPN has the following features:
z
It provides Layer 2 VPN tunnels that are simpler.
z
VLAN-VPN can be implemented without the support of signaling protocols. You
can enable VLAN-VPN by static configuration.
The VLAN-VPN function provides you with the following benefits:
z
Saves public network VLAN ID resource.
z
You can have VLAN IDs of your own, which is independent of public network
VLAN IDs.
z
Provides simple Layer 2 VPN solutions for small-sized MANs or intranets.
1.1.2 Implementation of VLAN-VPN
VLAN-VPN can be implemented by enabling the VLAN-VPN function on ports.
With the VLAN VPN function enabled, a received packet is tagged with the default
VLAN tag of the receiving port no matter whether or not the packet already carries a
VLAN tag. If the packet already carries a VLAN tag, the packet becomes a dual-tagged