NIC Teaming to ACI

With active/standby NIC Teaming, one interface is active and one or more is in a standby state.

There are different implementations of the failover process depending on the bonding implementation:

• The MAC address of the active interface stays identical after a failover, so there is no need to remap the IP address of the server to a new MAC address.
• When a failover happens, the newly active interface uses its own MAC address to send traffic. In this case, the IP-to-MAC mapping must be updated on all the servers in the same Layer 2 domain. Therefore, with this type of implementation, the server sends a GARP/RARP request after a failover.

With the first implementation, the bridge domain configuration does not require any change if the newly active interface starts sending traffic immediately after the failover. Since the endpoint information (MAC, IP and its combination) didn’t change, ACI leaf simply detects the endpoint move via the packet from the new interface with the same MAC and IP. The endpoint to TEP mapping in the COOP database on spine switches is also updated accordingly just like a normal endpoint move.

With the second implementation, the bridge domain must be configured for ARP flooding for the GARP request to reach the servers in the bridge domain. If ARP flooding is disabled and Unicast Routing is enabled, instead of flooding the GARP, ACI tries to route it to the target IP, which is the source of the GARP in the case of Gratuitous ARP, resulting in the GARP not being forwarded to anybody in the BD. Also, when the GARP packet enters the ACI leaf, it triggers an update in the Endpoint table for the IP-to-MAC mapping regardless of whether ARP flooding is enabled. There is a corner case where this endpoint update does not happen. In such cases, you may need to enable GARP-based detection for EP Move Detection Mode.