Configuring Qinq; Overview; How Qinq Works - HP 6125XLG Configuration Manual

Configuring QinQ

This document uses the following terms:
CVLAN—Customer network VLANs, also called inner VLANs, refer to VLANs that a customer uses
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on the private network.
SVLAN—Service provider network VLANs, also called outer VLANs, refer to VLANs that a service
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provider uses to transmit VLAN tagged traffic for customers.

Overview

802.1Q-in-802.1Q (QinQ) adds an 802.1Q tag to 802.1Q tagged customer traffic. It enables a service
provider to extend Layer 2 connections across an Ethernet network between customer sites.
QinQ provides the following benefits:
Enables a service provider to use a single SVLAN to convey multiple CVLANs for a customer.
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• Enables customers to plan CVLANs without conflicting with SVLANs.
Enables customers to keep their VLAN assignment schemes unchanged when the service provider
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changes its VLAN assignment scheme.
Allows different customers to use overlapping CVLAN IDs. Devices in the service provider network
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make forwarding decisions based on SVLAN IDs instead of CVLAN IDs.

How QinQ works

As shown in
tags:
CVLAN tag—Identifies the VLAN to which the QinQ frame belongs when it is transmitted in the
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customer network.
• SVLAN tag—Identifies the VLAN to which the QinQ frame belongs when it is transmitted in the
service provider network. The service provider allocates the SVLAN tag to the customer.
The devices in the service provider network forward a tagged frame based on its SVLAN tag. The
CVLAN tag is transmitted as part of the frame's payload.
Figure 51 Single-tagged Ethernet frame header and double-tagged Ethernet frame header
Figure 51, a QinQ frame transmitted over the service provider network carries the following
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