Configuring VLAN Stacking VLAN Stacking Overview
OmniSwitch 6800/6850/9000 Network Configuration Guide March 2008 page 6-5
VLAN Stacking Overview
VLAN Stacking provides a mechanism for defining a transparent bridging configuration through a service
provider network. This type of configuration is achieved using one of two methods: service-based VLAN
Stacking or port-based VLAN Stacking.
The service-based approach provides the ability to configure Ethernet services to provide VLAN Stacking
functionality. The port-based approach requires configuring VLAN Stacking functionality on a port level
or port-VLAN level. See “VLAN Stacking Modes” on page 6-8 for more information.
The major components of VLAN Stacking that provide this type of functionality are described as follows:
• Provider Edge (PE) Bridge—An ethernet switch that resides on the edge of the service provider
network. The PE Bridge interconnects customer network space with service provider network space. A
switch is considered a PE bridge if it transports packets between a customer-facing port and a network
port or between two customer-facing ports.
• Transit Bridge—An ethernet switch that resides inside the service provider network and provides a
connection between multiple provider networks. It employs the same SVLAN on two or more network
ports. This SVLAN does not terminate on the switch itself; traffic ingressing on a network port is
switched to other network ports. It is also possible for the same switch to function as a both a PE
Bridge and a Transit Bridge.
• Tunnel (SVLAN)—A tunnel, also referred to as an SVLAN, is a logical entity that connects customer
networks by transparently bridging customer traffic through a service provider network. The tunnel is
defined by an SVLAN tag that is appended to all customer traffic. This implementation provides the
following three types of SVLANs, which are both defined by the type of traffic that they carry:
•an SVLAN that carries customer traffic
•an SVLAN that carries provider management traffic
•an IP Multicast VLAN (IPMVLAN) that distributes multicast traffic
Note that port-based VLAN Stacking does not support two or more customers sharing the same tunnel
• Network Network Interface (NNI)—An NNI is a port that resides on either a PE Bridge or a Transit
Bridge and connects to a service provider network. Traffic ingressing on a network port is considered
SVLAN traffic and is switched to a customer-facing port or to another network port.
• User Network Interface (UNI)—A UNI is a port that resides on a PE bridge that connects to a
customer network and carries customer traffic. The UNI may consist of a single port or an aggregate of
ports and can accept tagged or untagged traffic.
Note that port-based VLAN Stacking provides two types of UNI ports: user-customer port and user-
provider port. A user-customer port connects to a customer network and carries customer traffic; a
user-provider port carries provider management traffic.
The following illustration shows how VLAN Stacking uses the above components to tunnel customer traf-
fic through a service provider network:
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