def iptag_set(self, iptag, addr, port, x, y):
        """Set the value of an IPTag.

        Forward SDP packets with the specified IP tag sent by a SpiNNaker
        application to a given external IP address.

        A :ref:`tutorial example <scp-and-sdp-tutorial>` of the use of IP Tags
        to send and receive SDP packets to and from applications is also
        available.

        Parameters
        ----------
        iptag : int
            Index of the IPTag to set
        addr : string
            IP address or hostname that the IPTag should point at.
        port : int
            UDP port that the IPTag should direct packets to.
        """
        # Format the IP address
        ip_addr = struct.pack('!4B',
                              *map(int, socket.gethostbyname(addr).split('.')))
        self._send_scp(x, y, 0, SCPCommands.iptag,
                       int(consts.IPTagCommands.set) << 16 | iptag,
                       port, struct.unpack('<I', ip_addr)[0])
Set the value of an IPTag.

        Forward SDP packets with the specified IP tag sent by a SpiNNaker
        application to a given external IP address.

        A :ref:`tutorial example <scp-and-sdp-tutorial>` of the use of IP Tags
        to send and receive SDP packets to and from applications is also
        available.

        Parameters
        ----------
        iptag : int
            Index of the IPTag to set
        addr : string
            IP address or hostname that the IPTag should point at.
        port : int
            UDP port that the IPTag should direct packets to.