Method for providing LAN address discovery and terminal emulation for LAN-connected personal computer (PCs) using xerox network system (XNS)

• US 5,539,736 A
• Filed: 10/04/1994
• Issued: 07/23/1996
• Est. Priority Date: 12/31/1992
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Inforzato, Sarah K., Skilton, Jonathan, Johnson, Robert A.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Nguyen, Chau T.
• Application Number:
  US08/317,569
• Time in Patent Office: 658 Days
• Field of Search: 370/60, 370/85.13, 370/85.14, 370/94.1, 370/94.3, 370/110.1, 370/82, 370/61, 370/85.1, 370/85.15, 370/92, 370/99, 340/825.02
• US Class Current: 370/402
• CPC Class Codes: H04L 12/4604 LAN interconnection over a backbone network, e.g. Internet, Frame Relay

Abstract

An interface which enables a LAN connected workstation to concurrently communicate with a plurality of computer platforms having respective network architectures over the same physical connection. The interface receives data from a LAN connection, examines the data and identifies the format being used. Based on the identified format, the interface determines the appropriate destination for the data and sends the data to that destination. Additionally, the interface enables a workstation running XNS software to run terminal emulation programs at the increased speed available from a LAN connection by enhancing the XNS protocol with (1) message segmentation and reassembly, (2) maximum packet size negotiation and (3) LAN address discovery.

Claims

1. In a system having at least one personal computer (PC) coupled to an interface means by a Local Area Network (LAN) connection, and at least one computer system coupled to said interface means, wherein said at least one PC does not have a preconfigured LAN address recorded at said interface means, wherein said system employs Xerox Network System (XNS) at a data link layer of a network architecture, a method for providing LAN address discovery of said one PC comprising the steps of:

a) posting a frame indicating that said at least one PC is looking for a connection (LfC frame);

b) broadcasting a frame, which identifies the LAN address for the at least one PC, from said at least one PC to said interface means through the LAN connection;

c) sending, in response to said broadcast frame, an establish connection (EC) frame from said interface means to said at least one PC;

d) sending, in response to said EC frame from said interface means, an EC frame from said at least one PC to said interface means;

e) opening, at said interface means, a logical connection between said at least one PC and said computer system; and

f) identifying said logical connection, at said interface means, using said LAN address identified in said broadcast frame.

2. In a system having at least one personal computer (PC) coupled to an interface means by a Local Area Network (LAN) connection, and at least one computer system coupled to said interface means, said at least one PC and said interface means being communicating partners, wherein said system employs a predetermined network architecture having a data link layer and a client layer for network communications, wherein said system employs Xerox Network System (XNS) at a data link layer of a network architecture, a method for providing terminal emulation features at LAN speeds comprising the steps of:

a) segmenting messages transmitted across the LAN connection of the system to a communicating partner;

b) reassembling messages received on the LAN connection from the communicating partner;

c) negotiating maximum packet size with the communicating partner; and

d) discovering, when necessary, LAN addresses for said at least one PC not having a preconfigured LAN address and requesting a connection, said step of discovering including

1) posting a frame indicating that said PC is looking for a connection (LfC frame);

2) broadcasting a frame, which identifies the LAN address for the at least one PC, from said at least one PC to said interface means through the LAN connection;

3) sending, in response to said broadcast frame, an establish connection (EC) frame from said interface means to said at least one PC;

4) sending, in response to said EC frame from said interface means, an EC frame from said at least one PC to said interface means;

5) opening, at said interface means, a logical connection between said at least one PC and said computer system; and

6) identifying said logical connection, at said interface means, using said LAN address identified in said broadcast frame.