Method and apparatus for interfacing a workstation to a plurality of computer platforms

• US 5,379,296 A
• Filed: 12/31/1992
• Issued: 01/03/1995
• Est. Priority Date: 12/31/1992
• Status: Expired due to Term

• Current Assignee: Unisys Corporation
• Original Assignee: Unisys Corporation
• Inventors: Haughey, Sarah K., Johnson, Robert A., Skilton, Jonathan
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): Nguyen, Chau T.
• Application Number:
  US07/999,113
• Time in Patent Office: 733 Days
• Field of Search: 370/94.1, 370/94.3, 370/85.13, 370/85.14, 370/82, 370/60, 370/61, 370/85.1, 370/85.3
• 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. A method for enabling a workstation to communicate with a plurality of computer systems compatible with respective network architectures having at least a data link layer and a client layer at least a level above the data link layer, wherein said workstation is coupled to an interface processor and said interface processor is coupled to said plurality of computer systems, comprising the steps of:

a) sending data, having a specific data structure corresponding to a respective network architecture, from said workstation to said interface processor destined for one of said computer systems, said specific data structure being unknown to said interface processor;

b) examining, at said interface processor, said data and identifying the data link layer of the respective network architecture corresponding with the specific data structure of said data;

c) determining a destination for said data, based on the identification made in step b); and

d) delivering said data to a process associated with the client layer of the respective network architecture servicing the destination determined in step c).

2. A system for enabling a workstation to communicate with a plurality of computer systems compatible with respective network architectures having at least a data link layer and a client layer at least a level above the data link layer, wherein said workstation is coupled to an interface processor and said interface processor is coupled to said plurality of computer systems, comprising:

means for sending data, having a specific data structure corresponding to a respective network architecture, from said workstation to said interface processor destined for one of said computer systems, wherein said specific data structure is unknown to said interface processor;

means for examining, at said interface processor, said data and identifying the data link layer of the respective network architecture corresponding with the specific data structure of said data;

means for determining a destination for said data, based on the identification made by the means for examining;

client layer means for servicing communications to and from said destination determined by said means for determining; and

means for delivering said data to said client layer means.

3. A method for enabling a workstation to communicate with a plurality of computer systems compatible with respective network architectures having at least a data link layer and a client layer, wherein said workstation is coupled to an interface processor and said interface processor is coupled to said plurality of computer systems, comprising the steps of:

a) sending data, having a format corresponding to a respective network architecture, from said workstation to said interface processor destined for one of said computer systems, said format being unknown to said interface processor;

b) examining, at said interface processor, said data and identifying the data link layer of the respective network architecture corresponding with the format of said data, said data including a field indicating one of type and length (type/length field), depending on the respective network architecture, and a checksum field, wherein step b) further comprises the steps of;

b1) byte reversing the type/length field;

b2) examining the value represented by the byte-reversed type/length field;

b3) examining the value of the checksum field; and

b4) identifying, based on the examinations in step b2) and step b3), the data link layer of the respective network architecture corresponding to the format of said data,

c) determining a destination for said data, based on the identification made in step b); and

d) delivering said data to a process associated with the client layer of the respective network architecture servicing the destination determined in step c).

4. A method for enabling a workstation to communicate with a plurality of computer systems compatible with respective network architectures having at least a data link layer and a client layer which is at least one level above the data link layer, wherein said workstation is coupled to an interface processor and said interface processor is coupled to said plurality of computer systems, comprising the steps of:

a) sending data, having a specific data structure corresponding to a respective network architecture, from said workstation to said interface processor destined for one of said computer systems, said specific data structure being unknown to said interface processor;

b) examining, at said interface processor, said data and identifying the data link layer of the respective network architecture corresponding with the specific data structure of said data;

c) determining a destination for said data, based on the identification made in step b); and

d) delivering said data directly to a process associated with the client layer of the respective network architecture servicing the destination determined in step c).