def _dpkt_read_frame(self):
        """Read frames."""
        from pcapkit.toolkit.dpkt import (ipv4_reassembly, ipv6_reassembly,
                                          packet2chain, packet2dict, tcp_reassembly,
                                          tcp_traceflow)

        # fetch DPKT packet
        timestamp, packet = next(self._extmp)

        # extract packet
        if self._dlink.value == 1:
            packet = self._expkg.ethernet.Ethernet(packet)
        elif self._dlink.value == 228:
            packet = self._expkg.ip.IP(packet)
        elif self._dlink.value == 229:
            packet = self._expkg.ip6.IP6(packet)
        else:
            warnings.warn('unrecognised link layer protocol; all analysis functions ignored',
                          DPKTWarning, stacklevel=stacklevel())
            self._frnum += 1
            if self._flag_d:
                self._frame.append(packet)
            return packet

        # verbose output
        self._frnum += 1
        self._proto = packet2chain(packet)
        if self._flag_v:
            print(f' - Frame {self._frnum:>3d}: {self._proto}')

        # write plist
        frnum = f'Frame {self._frnum}'
        if not self._flag_q:
            info = packet2dict(packet, timestamp, data_link=self._dlink)
            if self._flag_f:
                ofile = self._ofile(f'{self._ofnm}/{frnum}.{self._fext}')
                ofile(info, name=frnum)
            else:
                self._ofile(info, name=frnum)

        # record frames
        if self._flag_d:
            setattr(packet, 'packet2dict', packet2dict)
            setattr(packet, 'packet2chain', packet2chain)
            self._frame.append(packet)

        # record fragments
        if self._ipv4:
            flag, data = ipv4_reassembly(packet, count=self._frnum)
            if flag:
                self._reasm[0](data)  # pylint: disable=E1102
        if self._ipv6:
            flag, data = ipv6_reassembly(packet, count=self._frnum)
            if flag:
                self._reasm[1](data)  # pylint: disable=E1102
        if self._tcp:
            flag, data = tcp_reassembly(packet, count=self._frnum)
            if flag:
                self._reasm[2](data)  # pylint: disable=E1102

        # trace flows
        if self._flag_t:
            flag, data = tcp_traceflow(packet, timestamp, data_link=self._dlink, count=self._frnum)
            if flag:
                self._trace(data)

        return packet
Read frames.