Page 506 7750 SR OS Services Guide
VPLS Service Considerations
This section describes various 7750 SR service features and any special capabilities or
considerations as they relate to VPLS services.
SAP Encapsulations
VPLS services are designed to carry Ethernet frame payloads, so it can provide connectivity
between any SAPs and SDPs that pass Ethernet frames. The following SAP encapsulations are
supported on the 7750 SR VPLS service:
• Ethernet null
• Ethernet Dot1q
•Ethernet QinQ
• SONET/SDH BCP-null
• SONET/SDH BCP-dot1q
• ATM VC with RFC 2684 Ethernet bridged encapsulation (See ATM/Frame Relay PVC
Access and Termination on a VPLS Service on page 569.)
• FR VC with RFC 2427 Ethernet bridged encapsulation (See ATM/Frame Relay PVC
Access and Termination on a VPLS Service on page 569.)
VLAN Processing
The SAP encapsulation definition on Ethernet ingress ports defines which VLAN tags are used to
determine the service that the packet belongs:
1. Null encapsulation defined on ingress — Any VLAN tags are ignored and the packet goes to
a default service for the SAP.
2. Dot1q encapsulation defined on ingress — Only first label is considered.
3. QinQ encapsulation defined on ingress— Both labels are considered.
Note that the SAP can be defined with a wildcard for the inner label (for example, “100:*”).
In this situation all packets with an outer label of 100 will be treated as belonging to the SAP.
If, on the same physical link, there is also a SAP defined with a QinQ encapsulation of 100:1,
then traffic with 100:1 will go to that SAP and all other traffic with 100 as the first label will
go to the SAP with the 100:* definition.
In situations 2 and 3 above, traffic encapsulated with tags for which there is no definition are
discarded.
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