AOS-CX Active Gateway is used with a VSX pair to provide an active-active first-hop gateway. Both VSX peers share the same virtual IP address and virtual MAC address (VMAC), allowing either peer to route traffic received from downstream hosts.

HPE Aruba Networking documents that each Active Gateway periodically sends a broadcast hello packet so that downstream access switches continue learning the Active Gateway VMAC and do not age it out of their MAC address tables . HPE Support

For this Active Gateway hello mechanism, the relevant implementation is a Layer 2, non-IP Ethernet packet . This is consistent with its purpose: the packet is used primarily to refresh Layer 2 MAC learning for the shared VMAC rather than to establish an IP-layer neighbor relationship.

The other answers correspond to unrelated mechanisms. UDP port 5555 is associated in Aruba environments with functions such as AP packet-capture traffic, not VSX Active Gateway hello operation. Aruba Networks TCP port 6363 and multicast address 224.0.1.3 are likewise not used for Active Gateway hello messages.

Therefore, the correct answer is D. Non-IP Ethernet packet .

Study Guide Topics: AOS-CX VSX, Active Gateway, Virtual MAC Address, Active-Active First Hop Gateway, MAC Table Learning, Broadcast Hello Packets.