Forwarding detection of an aggregated interface

The techniques describe detecting connectivity failure of an aggregated interface. To monitor connectivity of the aggregated interface, a packet processor of a plurality of packet processors is set as a session master responsible for managing an active forwarding plane connectivity detection session with a peer session master node. The other local packet processors of the virtual network node are selected as session standby nodes that each have a passive forwarding plane connectivity detection session running to the peer session master node. If a session master node goes down (i.e., by link or node failure), one of the local session standby nodes may detect the failure and is set as a new session master node by activating its passive session having the same session parameters.