/// Taken from libpcap/bpf/net/bpf.h and pcap/net/bpf.h. ///
/// The link-layer type is used to determine what data-structure the /// IP protocol bits will be encapsulated inside of. ///
/// On a 10/100mbps network, packets are encapsulated inside of ethernet. /// 14-byte ethernet headers which contain MAC addresses and an ethernet type /// field. ///
/// On ethernet over ppp, the link-layer type is raw, and packets /// are not encapsulated in any ethernet header. ///
/// ///