ZyXEL Communications ES-100, User Manual

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Chapter 12 VLAN
MES-2110 User’s Guide
101
12.5 The Tag-Based VLAN Screens
Use the Tag-Based VLAN screens to configure VLAN settings.
12.5.1 VLAN Stacking
A service provider can use VLAN stacking to allow it to distinguish multiple
customers VLANs, even those with the same (customer-assigned) VLAN ID, within
its network.
Use VLAN stacking 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 service, 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
on ports for these applications. 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.
12.5.2 VLAN Stacking 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