arp_ip_eth(eth_port, ipaddr, ethaddr) looks for an entry in the arp table that matches ipaddr, the second parameter, and if it finds it, returns the corresponding ethernet address in ethaddr, the third parameter. If arp_ip_eth() does not find a valid entry in the arp table for the ip address, it sends out an arp broadcast in an attempt to find the ethernet address for the ip address and returns NW_SUSPEND.