ZyXEL IES-612-51A User Manual download pdf (Page 211)

IES-612-51A User’s Guide

211

CHAPTER 30

TLS PVC

This chapter shows you how to set up Transparent LAN Service (VLAN stacking, Q-in-Q) on

each port.

30.1 Transparent LAN Service (TLS) Overview

Transparent LAN Service (also known as VLAN stacking or Q-in-Q) allows a service provider

to distinguish multiple customers VLANs, even those with the same (customer-assigned)

VLAN ID, within its network.

Use TLS to add an outer VLAN tag to the inner IEEE 802.1Q tagged frames that enter the

network. By tagging the tagged frames (“double-tagged” frames), the service provider can

manage up to 4,094 VLAN groups with each group containing up to 4,094 customer VLANs.

This allows a service provider to provide different services, based on specific VLANs, for

many different customers.

A service provider’s customers may require a range of VLANs to handle multiple

applications. A service provider’s customers can assign their own inner VLAN tags to traffic.

The service provider can assign an outer VLAN tag for each customer. Therefore, there is no

VLAN tag overlap among customers, so traffic from different customers is kept separate.

Before the IES-612-51A sends the frames from the customers, the VLAN ID is added to the

frames. When packets intended for specific customers are received on the IES-612-51A, the

outer VLAN tag is removed before the traffic is sent.

30.1.1 TLS Network Example

In the following example figure, both A and B are Service Provider’s Network (SPN)

customers with VPN tunnels between their head offices and branch offices, respectively. Both

have an identical VLAN tag for their VLAN group. The service provider can separate these

two VLANs within its network by adding tag 37 to distinguish customer A and tag 48 to

distinguish customer B at edge device 1 and then stripping those tags at edge device 2 as the

data frames leave the network.

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ZyXEL IES-612-51A User Manual Page 211