This callback can be given to scapy's sessions() to group traffic full-duplex. It's a very general solution that can handle all Ethernet packets and makes grouping keys from which information can be easily extracted (see example below).
# Callback to make sessions() group traffic full-duplex, rather than
# half-dupelex, as would be the default. Basically returns a grouping
# key of the following format (between and excluding the ticks):
# `<L_2>|<L_3>|<L_4> <MAC_1>~<IP_1>~<PORT_1> <MAC_2>~<IP_2>~<PORT_2>`
# Where <L_*> are the protocols on the respective layer, specified by
# their corresponding scapy class name, layers not in packet omitted.
# <MAC_*>, <IP_*> and <PORT_*> are MAC, IP and port, respectively.