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.

• Enables customers to plan CVLANs without conflicting with SVLANs.

• Enables customers to keep their VLAN assignment schemes unchanged when the service provider changes its VLAN assignment scheme.

• Allows different customers to use overlapping CVLAN IDs. Devices in the service provider network make forwarding decisions based on SVLAN IDs instead of CVLAN IDs.