/// The following is the packet structure used for ARP requests and replies.
/// On Ethernet networks, these packets use an EtherType of 0x0806, and are sent to the broadcast MAC address of FF:FF:FF:FF:FF:FF.
/// Note that the EtherType (0x0806) is used in the Ethernet header, and should not be used as the PTYPE of the ARP packet.
/// The ARP type (0x0806) should never be used in the PTYPE field of an ARP packet, since a hardware protocol address should never be linked to the ARP protocol.
/// Note that the packet structure shown in the table has SHA and THA as 48-bit fields and SPA and TPA as 32-bit fields but this is just for convenience
/// their actual lengths are determined by the hardware & protocol length fields.