The Node ARP Management Daemon (rca_arpd)

The node ARP management daemon (rca_arpd) manages the system ARP cache. This daemon deletes the IP to hardware address (ARP) mappings for failed nodes and reads them when they become available. It only manages ARP mappings on the high speed interconnect network and not external network interfaces such as Ethernet. If failover is configured, rca_arpd also manages ARP mappings for the backup boot or SDB node. When a node failed event from the primary boot or SDB node is received, rca_arpd updates the ARP mapping for the boot or SDB node virtual IP address to point to the backup node.

This functionality is included in the cray-rca-compute and cray-rca-service RPMs and is installed by default.