Title: arp_set_cb()

During the initialization of the network service (and, more specifically, the initialization of the ip layer), arp_set_cb(eth_port, ip_port, arp_func) is called to initialize the arp port associated with the ethernet port eth_port, arp_set_cb()'s first parameter. After initializing the arp port, arp_set_cb() calls arp_main().

It is unclear what the "cb" in the function name stands for.