Implementation Of Vlan-Vpn; Configuring The Tpid For Vlan-Vpn Packets - H3C S3100-52P Operation Manual

Operation Manual – VLAN-VPN
H3C S3100-52P Ethernet Switch
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Figure 1-2 Structure of packets with double-layer VLAN tags
Compared with MPLS-based Layer 2 VPN, VLAN-VPN has the following features:
It provides Layer 2 VPN tunnels that are simpler.
VLAN-VPN can be implemented through manual configuration. That is, signaling
protocol-related configuration is not needed.
The VLAN-VPN feature provides you with the following benefits:
Saves public network VLAN ID resource.
You can have VLAN IDs of your own, which is independent of public network
VLAN IDs.
Provides simple Layer 2 VPN solutions for small-sized MANs or intranets.

1.1.2 Implementation of VLAN-VPN

With the VLAN-VPN feature enabled, no matter whether or not a received packet
already carries a VLAN tag, the switch will tag the received packet with the default
VLAN tag of the receiving port and add the source MAC address to the MAC address
table of the default VLAN. When a packet reaches a VLAN-VPN-enabled port:
If the packet already carries a VLAN tag, the packet becomes a dual-tagged
packet.
Otherwise, the packet becomes a packet carrying the default VLAN tag of the port.

1.1.3 Configuring the TPID for VLAN-VPN Packets

A VLAN tag uses the tag protocol identifier (TPID) field to identify the protocol type of
the tag. The value of this field is 0x8100 for IEEE 802.1Q.
Figure 1-3
Figure 1-3 The structure of the VLAN tag in an Ethernet frame
Destination MAC address
illustrates the structure of the IEEE 802.1Q VLAN tag in an Ethernet frame.
Chapter 1 VLAN-VPN Configuration
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Source MAC address
Outer VLAN Tag
Inner VLAN Tag
Data
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