Which of the following statements about the operation of a single-homed EVPN VPWS is TRUE?

In a single-homed EVPN VPWS (Virtual Private Wire Service), when the local attachment circuit (AC) becomes operationally active, the Provider Edge (PE) router signals the service availability to remote PEs. It does this by advertising an Ethernet Auto-Discovery (A-D) per EVI route (Type 1). This route must contain two critical pieces of information: a non-zero Ethernet Tag ID, which uniquely identifies the service instance on the advertising PE, and a non-zero, downstream-assigned MPLS label. The remote PE uses this advertised label to encapsulate and forward traffic destined for the local AC, thus establishing the data plane for the point-to-point service.

A. The Ethernet Tag ID is locally significant to each PE. While they can be the same, it is not a requirement; each PE can use a different tag ID for its end of the VPWS.

B. EVPN VPWS is a point-to-point service that does not perform MAC learning. Therefore, it only uses Ethernet A-D per EVI routes for service signaling, not MAC/IP Advertisement routes (Type 2).

D. A PE uses the received tag ID to identify the remote endpoint of the VPWS service. It does not compare the received tag ID with its own locally configured tag ID.

1. Nokia 7750 SR OS Services Guide, Release 21.10.R1, Section: EVPN-VPWS for Epipe Services.

Page 1038: "When the SAP is up, the PE advertises a single Ethernet A-D per EVI route... The route includes the configured eth-tag, a VTEP address, and a downstream-assigned MPLS label." This supports that a non-zero tag and label are advertised (Answer C) and contradicts the use of MAC routes (Answer B).

2. RFC 8214: Virtual Private Wire Service Support in Ethernet VPN, Section 5.1. Ethernet A-D per EVI Route Advertisement.

Paragraph 2: "The Ethernet Tag ID is set to the service-instance identifier of the E-Line service... The MPLS Label field is set to a valid, non-zero MPLS label." This directly confirms that the advertised route includes a non-zero tag ID and a non-zero MPLS label (Answer C).

3. Nokia 7750 SR OS Services Guide, Release 21.10.R1, Section: EVPN-VPWS single-homing.

Page 1038: The configuration examples show that the eth-tag is configured locally on each PE under the bgp-evpn context of the Epipe service. The text does not mandate that the local and remote tag IDs must be identical, invalidating option A and D's premise of matching local tags.