Example screenshots (R&S RTM3004)

Start of packet.
Bus D0 goes high when carrier detected.
Bus D1 goes high at first byte of source MAC address. This allows triggering without using additional channels. Trigger holdoff should be used to avoid retriggering on packet content. This may not work well where there is a wide range of packet lengths.
MARK pulses once per byte within packet

End of packet

SW2 ON : MARK indicates important fields in packet. Buses shown in hex and decimal.

Mid packet

End of packet

Byte index mode (SW1=ON)

 Byte index mode ( SW1=ON), long packet showing count bit 8 in MARK channel