Which of the following most accurately describes the default behavior of a VPLS regarding the handling of a tagged frame at the ingress of SAP 1/1/1:100?

The SAP identifier 1/1/1:100 specifies a dot1q encapsulation, where the VLAN tag 100 is used to classify incoming traffic into the VPLS service. By default, when a tagged frame arrives at an ingress dot1q SAP, the router first verifies the Frame Check Sequence (FCS) for integrity. The VLAN tag (100) has served its purpose of identifying the service, so it is removed (stripped) from the frame. The original FCS is also discarded because the frame has been modified (tag removed) and will be encapsulated with new MPLS headers for transport. A new FCS will be calculated at the egress PE.

A. The frame is not transported intact; the customer's classification VLAN tag is removed by default on a dot1q SAP.
B. The VLAN tag is removed by default, and the original FCS is also discarded, not kept.
C. The VLAN tag is removed by default on a dot1q SAP, not kept for transport.

1. Nokia 7750 SR OS Services Guide, Release 21.10.R1, "VPLS" chapter, Section: "VPLS Service Access Points (SAPs)". This section describes the behavior of different SAP encapsulation types, stating that for encap-type dot1q, the qualifying VLAN tag is stripped on ingress.

2. Nokia 7750 SR and 7450 ESS MPLS Guide, Release 21.10.R1, "Layer 2 Services" chapter. The guide explains the frame processing path, which includes stripping service-delimiting tags and recalculating the FCS before MPLS encapsulation.