Dial-up router and method of controlling outgoing of the dial-up router

#This invention relates to a dial-up router which is for use in constituting a network by connecting a local area network (LAN) with a wide area network (WAN), and also to a method of controlling outgoing of the dial-up router.

#Recently, dial-up routers for connecting and relaying local area networks (LAN) with wide area networks (WAN) including a private line, an ISDN, the other public transmission circuit network, and the like by a dial-up connection have come into wide use with the utilization of internet.

#Generally, a dial-up router functions to connect or disconnect terminals at LAN side with WAN such as ISDN, or the like as occasion demands. In such a case, a destination address of packet data which has reached the dial-up router from LAN in accordance with communication protocol, such as TCP/IP, or the like is investigated by the dial-up router, as a necessary condition for outgoing. If the destination address is directed to WAN, the dial-up router automatically transmits the packet data to a transmission circuit of WAN.

#FIG. 1 is a schematic block diagram for showing an example of a network which is constituted by the use of a conventional dial-up router;

#FIG. 2 is a schematic block diagram for showing an example of a network which is constituted by the use of a dial-up router according to a preferred embodiment of the present invention;

#FIG. 3 is a block diagram for showing detailed structures of the dial-up router and the personal computer illustrated in FIG. 2;

#Referring to FIG. 1, description is, at first made about a conventional dial-up router in order to facilitate an understanding of the present invention. FIG. 1 is a schematic block diagram for showing an example of a network which is constituted by the use of the conventional dial-up router.

#As illustrated in FIG. 1, personal computers (PC) 2 and 3 are connected with LAN 4 while LAN 4 and WAN 5 are connected with each other by a dial-up router 1. In addition, a World Wide Web (WWW) server 6 is connected with LAN 4 in FIG. 1.

#As mentioned in the preamble of the instant specification, the dial-up router 1 functions to connect or disconnect terminals at the LAN side (PC 2, 3) with WAN 5, such as ISDN, or the like as occasion demands. In such a case, a destination address of packet data which has reached the dial-up router 1 from LAN 4 in accordance with communication protocol, such as TCP/IP, or the like is investigated by the dial-up router 1, as a necessary condition for outgoing. If the destination address is directed to WAN 5, the dial-up router 1 automatically transmits the packet data to a transmission circuit of WAN 5.