Layer 2 VPN Service Deliminators
Service deliminators are used to define how the customer is identified to the Layer 2 VPN service.
There are multiple types of service deliminators. The ExtremeXOS software currently supports three types. The first is a VLAN service. This service transparently interconnects two or more VLAN segments together over an MPLS network. The configured VLAN IDs for the customer switch interfaces are not required to match, as long as the egress LSR overwrites the VLAN tag with the locally defined VLAN ID.
The second service is a VMAN service, which interconnects two or more VMAN segments. The service operates like the VLAN service but uses the VMAN tag instead of the VLAN tag to identify the service. As with the VLAN service, the interconnected VMAN segments do not need to have matching VMAN IDs.
The third service is a port service, which transparently interconnects two or more ports together over an MPLS network. Traffic is transported unmodified between ports.
The VLAN and VMAN services are configured by adding the service VLAN or a VMAN to a VPLS or VPWS. The port service is not explicitly configured but is emulated using a combination of Layer 2 VPN capabilities. First a VMAN must be configured and the port added untagged to the VMAN. The service VMAN is then added to the VPLS or VPWS. At this point all traffic received on the port is VMAN encapsulated for transmission across the Layer 2 VPN. To transmit the traffic across the Layer 2 VPN as it was received on the port, the VPLS or VPWS is configured to exclude the service tag. By excluding the service tag, the VMAN tag is stripped prior to being transmitted from the switch. This configuration provides port mode service and allows one or multiple ports to be associated with a Layer 2 VPN.