Apparatus and method for interconnecting ISDN/internetwork users

• US 5,745,702 A
• Filed: 08/22/1995
• Issued: 04/28/1998
• Est. Priority Date: 08/22/1994
• Status: Expired due to Term

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Morozumi, Hisashi
• Primary Examiner(s): Lall, Parshotam S.
• Assistant Examiner(s): Winder, Patrice L.
• Application Number:
  US08/518,074
• Time in Patent Office: 980 Days
• Field of Search: 395/200.02, 395/200.12, 395/200.15, 395/200.48, 395/200.57, 395/200.79, 370/401, 370/402, 370/466
• US Class Current: 709/249
• CPC Class Codes: H04L 12/4612 LAN interconnection over narrowband networks, e.g. N-ISDN, PSTN, X.25

Abstract

A LAN interconnection apparatus is coupled through a first port to an ISDN and through a second port to a local area network (LAN). Through the ISDN, the apparatus is connected to a remote LAN or an ISDN user. A network address and a host address of an internetwork (such as the Internet) as well as a telephone number of the ISDN are used to uniquely identify remote LANs and ISDN users. A database is provided for associating network addresses with port numbers of the apparatus and associating host addresses with telephone numbers. Upon receipt of a call indication, the apparatus stores a source telephone number contained in the call indication into a lookup table. In response to a packet from the LAN, a port number and a telephone number are detected in the database using a network address and a host address contained in the packet, respectively, as keys. The received packet is then forwarded as a message packet to the port of the detected port number if the detected telephone number is stored in an entry of the lookup table corresponding to the detected port number. The detected telephone number is stored into the lookup table if that number is not stored in the lookup table and the received packet is then forwarded as a call setup packet to the port of the detected port number.

Claims

1. An apparatus for interconnecting a LAN (local area network) and remote stations through an integrated services digital network (ISDN), each of said LAN and remote stations being a user of an internetwork and being assigned a network address and a host address of the internetwork and a telephone number of the ISDN, the apparatus comprising:

a first port connected to the LAN and a second port connected to the ISDN, said first and second ports being respectively identified by a port number;

a database having a plurality of entries associating network addresses with said port numbers and a plurality of entries associating host addresses with telephone numbers;

a lookup table having a plurality of entries corresponding to said port numbers; and

control means for (a) receiving a call indication signal through the second port and storing a source telephone number contained in the call indication signal into an entry of the lookup table corresponding to the port number of the second port, (b) receiving a packet from the LAN, detecting a port number in an entry of the database corresponding to a network address contained in the received packet, detecting a telephone number in an entry of the database corresponding to a host address contained in the packet and forwarding the received packet as a message packet to the port of the detected port number if the detected telephone number is stored in an entry of the lookup table corresponding to the detected port number, and storing the detected telephone number into an entry of the lookup table corresponding to the detected port number if the detected telephone number is not stored in said entry of the lookup table and forwarding the received packet as a call setup packet to the port of the detected port number.

2. In an apparatus having a first port connected to an Integrated services digital network (ISDN) and a second port connected to a LAN (local area network) for exchanging packets with remote stations through the ISDN, each of said LAN and remote stations being a user of an internetwork and assigned a network address and a host address of the internetwork and a telephone number of the ISDN, said first and second ports being identified by a respective port number, a communication method comprising the steps of:

a) storing network addresses and said port numbers in respective entries of a database and storing host addresses and telephone numbers in respective entries of the database;

b) receiving a signal through one of the first and second ports and determining a type of the received signal;

c) if the received signal is determined to be a call indication signal from the ISDN, storing a source telephone number contained in the received signal into an entry of a lookup table corresponding to the port number of the first port;

d) if the received signal is determined to be a packet from the LAN, detecting a port number in an entry of the database corresponding to a network address contained in the received packet and detecting a telephone number in an entry of the database corresponding to a host address contained in the received packet, and determining whether or not the detected telephone number is stored in an entry of said lookup table corresponding to the detected port number;

e) if the detected telephone number is determined to be not stored in said lookup table, storing the detected telephone number into said entry of the lookup table and forwarding the received packet as a call setup packet to the port of the detected port number; and

f) if the detected telephone number is determined to be stored in said entry of said lookup table, forwarding the received message packet as a message packet to the port of the detected port number.