Alcatel-Lucent 1643 AMS Applications And Planning Manual page 210

Ethernet Overview
VPN tagging is characterized as follows:
• VPN tagging is a double tagging mode. This means that a customer identifier (CID
tag) is inserted into each frame at each network ingress LAN port. User frames that
are already tagged become double tagged. The CID tag is removed from the frame
at each network egress LAN port.
• Ports forward only those frames that have a CID tag which "belongs" to that port
(i.e. which has previously been provisioned on that port).
In the VPN tagging mode, the term "LAN group" is synonymously used to the term
"virtual switch".
Configuration rules and guidelines
Please observe these configuration rules and guidelines:
• Be aware that the port role of the LAN and WAN ports is fixed (see above):
– LAN ports are always customer role ports.
– WAN ports are always network role ports.
• On LAN ports the CID needs to be provisioned manually.
• The CID provisioned on each LAN port must be unique within a shared WAN to
create a fully independent VPN.
The VPN provisioning on the WAN ports is done automatically by means of the
proprietary spanning tree with VPN registration protocol (STVRP).
IEEE 802.1Q STP virtual switch mode
The IEE802.1Q/IEEE 802.1ad VLAN tagging scheme can be seen as an extension of
the LAN-VPN mode, providing more flexibility in defining the VPN's and in general
leading to a more efficient use of bandwidth. In IEEE 802.1Q VLAN tagging mode, a
virtual switch is formed by a combination of LAN- and WAN ports on a physical
switch that is used by different VLAN's which can share the common WAN
bandwidth. Each port can be part of only one virtual switch, but a certain port may be
associated with more than one VLAN. The ports that are associated with a certain
VLAN ID form the VLAN Port Member Set.
On ingress, each packet is filtered on its VLAN ID. If the receiving port is a member
of the VLAN to which a received MAC frame is classified, then the frame is
forwarded. The user can provision whether untagged packets are dropped, or tagged
with a PVID (Port VLAN ID), via the acceptable frame type parameter.
Example VLAN trunking
The VLAN trunking example shown in the next figure is one of the possible
applications in this operation mode.
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11-34 Alcatel-Lucent - Proprietary
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Operational modes
365-312-801R7.2
Issue 3, May 2007