Vlan Stacking Overview - ZyXEL Communications VES-1616 Support Notes

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VLAN Stacking Overview

VLAN stacking allows a carrier to offer multiple virtual LANs over a single circuit.
In essence, the carrier creates an Ethernet VPN to tunnel customer VLANs
across its WAN. Thus it helps to avoid name conflicts among customers of
multiple service providers who connect to the same carrier.
VLAN stacking works by assigning two VLAN IDs to each frame header. One is a
"backbone" VLAN ID used by the service provider, the other (up to 4,096 unique
802.1Q VLAN tags) is used by the customers.
The following figure shows a network example.
Company YY branch
Switch
H
Port 17
VLAN 2
Switch
A
Company XX HQ
In this example, company XX and company YY both subscribe to the same ISP
for Internet service. Both companies have an internal VLAN group with VID 1. In
order to prevent VLAN-tagged packets between these two companies from
transmitting to each other's network, VLAN stacking is implemented in the ISP's
network. The ISP assigns a service provider VID for each company- company XX
is assigned an SP VID of 30 and company YY is assigned an SP VID of 40.
The following shows the packet flow between Company XX HQ and its branch
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VLAN 30|VLAN 2
Port
Port
25
Switch Port
2
B 25
Port
VLAN 40|VLAN 2
1
Port 17
2
VLAN 2
1
VES-1616/24FA-5x Series Support Notes
Company XX branch
Port 25
Switch
VLAN 30|VLAN 2
D
Switch Port
C 26
Port
VLAN 40|VLAN 2
27
Port 25
Switch G
Port
1
VLAN 2
Company YY HQ
Switch
E
Port 17
VLAN 2
Port
1
3
Port 17
Switch
F
44