Which of the following statements about EVPN auto-discovery per EVPN instance (A-D per EVI) routes is FALSE?

Statement (D) is false because it incorrectly describes the scope and primary purpose of the EVPN Auto-Discovery (A-D) per EVI route. The discovery of all PEs attached to an Ethernet Segment (ES) for functions like Designated Forwarder (DF) election is the specific role of the A-D per ES route.

The A-D per EVI route, as its name implies, is scoped to a specific EVPN Instance (EVI) or service. It is used to discover other PEs on the same ES that are also part of that specific service. Its primary functions are to enable aliasing (for all-active multi-homing) and mass MAC withdrawal for that service. It cannot be used to discover a PE on the ES that does not participate in that particular EVI.

A: This is a true statement. Remote PEs use the collection of received A-D per EVI routes from PEs in an all-active segment to build a next-hop list (aliasing) for load-balancing traffic.

B: This is a true statement. A PE attached to an Ethernet Segment generates and advertises a distinct A-D per EVI route for every single service (EVI) that is operationally active on that segment.

C: This is a true statement. According to RFC 7432, the Ethernet A-D per EVI route (Type 1) is defined to have the Ethernet Tag ID field set to zero, as it applies to the entire EVI on the segment, not a specific VLAN.

1. Nokia 3HE 17175 AAAA TQZZA 01, SR OS 22.10 Services Architecture Guide, Chapter: EVPN for VPLS and Epipe services, Section: EVPN route types.

This guide distinguishes between the two Type 1 routes. It states, "The Ethernet A-D per ES route is advertised per Ethernet segment and is used for DF election." This confirms that discovering all PEs for core multi-homing is the role of the per-ES route. It then describes the A-D per EVI route: "This route is advertised per EVI... It is used for aliasing and backup... It is also used for mass-withdrawal." This confirms the EVI-scoped functions of the A-D per EVI route, contradicting statement (D).

2. RFC 7432: BGP MPLS-Based Ethernet VPN, Section 8.2.1. Ethernet A-D per EVI Route.

This section specifies, "The Ethernet Tag ID is a 4-octet field that is set to 0." This confirms that statement (C) is true. The RFC also details how these routes are used for mass withdrawal and aliasing, confirming statement (A) is true.

3. Nokia 3HE 17175 AAAA TQZZA 01, SR OS 22.10 Services Architecture Guide, Chapter: EVPN for VPLS and Epipe services, Section: Ethernet A-D per EVI route advertisement.

This section states, "The Ethernet A-D per EVI route is advertised when an Ethernet-segment is configured on a SAP or SDP-binding and the SAP or SDP-binding is operationally up." This directly confirms that statement (B) is true.