How Vlan Stacking Works - Alcatel-Lucent OmniSwitch 9900 Series Network Configuration Manual

Configuring VLAN Stacking

How VLAN Stacking Works

On the Provider Edge bridge (PE), a unique tunnel (SVLAN) ID is assigned to each customer. The tunnel
ID corresponds to a VLAN ID, which is created on the switch when the tunnel is configured. For example,
when tunnel 100 is created, VLAN Stacking software interacts with VLAN Manager software to configure
a VLAN 100 on the switch. VLAN 100 is the provider bridge VLAN that will tunnel customer VLAN
traffic associated with tunnel 100. So, there is a one to one correspondence between a tunnel and its
provider bridge VLAN ID. In fact, tunnel and VLAN are interchangeable terms when referring to the
provider bridge configuration.
VLAN Stacking refers to the tunnel encapsulation process of appending to customer packets an 802.1Q
tag that contains the tunnel ID associated to that customer's provider bridge port and/or VLANs. The
encapsulated traffic is then transmitted through the Ethernet metro area network (EMAN) cloud and
received on another PE bridge that contains the same tunnel ID, where the packet is then stripped of the
tunnel tag and forwarded to the traffic destination.
The following provides an example of how a packet ingressing on a VLAN Stacking UNI port that is
tagged with the customer VLAN (CVLAN) ID transitions through the VLAN Stacking encapsulation
process:
1
Packet with CVLAN tag ingressing on a user port.
MAC DA
(6)
2
Double Tagging inserts the SVLAN tag in the packet. The packet is sent out the network port with
double tags (SVLAN+CVLAN).
MAC DA
MAC SA
(6)
(6)
3
VLAN Translation replaces the CVLAN Tag with SVLAN Tag. The packet is sent out the network
port with a single tag (SVLAN).
MAC DA
(6)
OmniSwitch AOS Release 8 Network Configuration Guide
MAC SA
CVLAN Tag
(6)
(4)
SVLAN Tag
(4)
MAC SA
SVLAN Tag
(6)
(4)
ETYPE
0x0800
ETYPE
CVLAN Tag
0x0800
(4)
ETYPE
0x0800
December 2017
VLAN Stacking Overview
Payload
Payload
Payload
page 35-5