Sending heartbeat packets with a configured MAC Address

On the VLAN interfaces of a routing switch, the user-defined MAC address only applies to inbound traffic. As a result, any connected switches need to learn the new address that is included in the Ethernet frames of outbound VLAN traffic transmitted from the routing switch.

If a connected switch does not have the newly configured MAC address of the routing switch as a destination in its MAC address table, it floods packets to all of its ports until a return stream allows the switch to learn the correct destination address. As a result, the performance of the switch is degraded as it tries to send Ethernet packets to an unknown destination address.

To allow connected switches to learn the user-configured MAC address of a VLAN interface, the HPE routing switch can send periodic heartbeat-like Ethernet packets. The Ethernet packets contain the configured MAC address as the source address in the packet header. IP multicast packets or Ethernet service frames are preferred because they do not interrupt the normal operation of client devices connected on the segment.

Because the aging time of destination addresses in MAC address tables varies on network devices, you must also configure a time interval to use for sending heartbeat packets.

Heartbeat packets are sent at periodic intervals with a specific switch unicast MAC address in the destination field. This MAC address is assigned to the switch and is not used by other non-HPE routers. Because the heartbeat packet contains a unicast MAC address, it does not interrupt host operation. Even if you have multiple 1-65 Static Virtual LANs (VLANs) Introducing tagged VLAN technology into networks running untagged VLANs switches connected to the network, there is no impact on network performance because each switch sends heartbeat packets with its configured MAC address as the destination address.

The format of a heartbeat packet is an extended Ethernet OUI frame with an extended OUI Ethertype (88B7) and a new protocol identifier in the 5-octet protocol identifier field.