val layer2_pdu_to_layer3_pdu : PDU.layer2_pdu -> PDU.layer3_pdu option
val layer3_pdu_to_layer4_pdu : PDU.layer3_pdu -> PDU.layer4_pdu option
val layer2_pdu : PDU.pdu -> PDU.layer2_pdu option
val layer3_pdu : PDU.pdu -> PDU.layer3_pdu option
val layer4_pdu : PDU.pdu -> PDU.layer4_pdu option
val ether_frame : PDU.pdu -> PDU.ether_frame option
val ether_payload : PDU.pdu -> PDU.ether_payload option
val ipv4_pkt : PDU.pdu -> PDU.ipv4_pkt option
val ipv4_payload : PDU.pdu -> PDU.ipv4_payload option
val ipv6_pkt : PDU.pdu -> PDU.ipv6_pkt option
val ipv6_payload : PDU.pdu -> PDU.ipv6_payload option
val icmpv4_pkt : PDU.pdu -> PDU.icmpv4_pkt option
val icmpv4_payload : PDU.pdu -> PDU.icmpv4_payload option
val icmpv6_pkt : PDU.pdu -> PDU.icmpv6_pkt option
val icmpv6_payload : PDU.pdu -> PDU.icmpv6_payload option
val tcp_pdu : PDU.pdu -> PDU.tcp_pdu option
val tcp_payload : PDU.pdu -> PDU.tcp_payload option
val udp_pdu : PDU.pdu -> PDU.udp_pdu option
val udp_payload : PDU.pdu -> PDU.udp_payload option