Gateway system for interconnecting different data communication networks

• US 5,680,552 A
• Filed: 09/20/1994
• Issued: 10/21/1997
• Est. Priority Date: 09/20/1994
• Status: Expired due to Term

• Current Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Sabnani, Krishan Kumar, Netravali, Arun Narayan
• Primary Examiner(s): SHAH, ALPESH
• Application Number:
  US08/309,213
• Time in Patent Office: 1,127 Days
• Field of Search: 395/200.01, 395/200.02, 395/200.06, 395/200.1, 395/200.2, 395/500, 395/182.02, 395/182.13, 395/200.12, 370/60, 370/62, 370/65, 370/53, 370/112, 370/54, 370/85.13, 370/85.14, 370/85.9, 370/94.1, 370/94.3, 379/14, 379/219, 379/220
• US Class Current: 709/250
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A gateway system for connecting first and second communication networks has first and second network end nodes and a protocol converter. The gateway system operates to provide input-output services of both network protocols to users of both networks in communicating through the gateway system. The gateway system employs associated complement protocol circuits in the end nodes and the protocol converter to provide these services. An efficient technique for generating the complement protocol of a first network is to prune finite state machines representing the operation of the second network protocol to provide the services of the second protocol that are not provided by the first protocol. The complement protocol circuits for the second network are then constructed based on the pruned finite state machines representing the operation of the first protocol.

Claims

1. A method for generating a gateway system between first and second networks implementing corresponding first and second communication protocols which provide first and second sets of services, respectively, wherein each protocol can be represented by a set of at least one finite state machine (FSM), the method comprising the steps of:

determining a common subset of services equal to a subset of the intersection of services provided by the protocols;

determining first and second complement service FSMs for the first and second network protocols, wherein the first complement service FSM contains those services provided by the second network protocol that are not characterized in the first network protocol, and wherein a second complement service FSM contains those services provided by the first network protocol that are not characterized in the second network protocol;

pruning the set of second network protocol FSMs to provide only operations corresponding to the services performed by the first complement service FSM to generate a first set of complement network protocol FSMs;

pruning the set of first network protocol FSMs to provide only operations corresponding to the services performed by the second complement service FSM to generate a second set of complement network protocol FSMs; and

constructing a gateway system based on the first and second set of protocol FSMs, the first and second set of complement protocol FSMs and an interface converter.

2. The method of claim 1, wherein each of the steps of pruning the set of protocol FSMs to generate a corresponding complement protocol FSM comprises the steps of:

deleting an edge from a first protocol service FSM corresponding to a service not characterized in a second protocol service FSM, and deleting an edge from the second protocol service FSM corresponding to a service not characterized in the first service FSM to form a first set of pruned FSMs;

deleting an edge from the first set of pruned FSMs which represent unmatched service primitives to form a second set of pruned FSMs; and

deleting an edge in the second set of pruned FSMs which are not within a strongly connected component of the corresponding second pruned FSM that contains the initial state to form a third set of pruned FSMs.

3. The method of claim 1, wherein the step of determining first and second complement protocols comprises the steps of:

pruning protocol FSMs characterizing the services provided by the protocols by removing edges in the service FSMs that correspond to services provided in the common subset of services.

4. A method for generating a gateway system between first and second networks implementing corresponding first and second communications protocols which provide first and second sets of services, respectively, wherein each protocol can be represented by a set of at least one finite state machine (FSM), the method comprising the steps of:

determining a common subset of services equal to a subset of the intersection of services provided by the protocols;

determining first and second complement service FSMs for the first and second network protocols, wherein the first complement service FSM contains those services provided by the second network protocol that are not characterized in the first network protocol, and wherein the second complement service FSM contains those services provided by the first network protocol that are not characterized in the second network protocol;

pruning the set of second network protocol FSMs to provide only operations corresponding to the services performed by the first complement service FSM to generate a first set of complement network protocol FSMs;

pruning the set of first network protocol FSMs to provide only operations corresponding to the services performed by the second complement service FSM to generate a second set of complement network protocol FSMs; and

constructing a gateway system employing circuit equivalents of the first and second set of protocol FSMs, the first and second set of complement protocol FSMs and an interface converter, wherein each of the steps of pruning the set of protocol FSMs to generate a corresponding complement protocol FSM comprises the steps of;

deleting an edge from a first protocol service FSM corresponding to a service not characterized in a second protocol service FSM, and deleting an edge from the second protocol service FSM corresponding to a service not characterized in the first protocol service FSM to form a first set of pruned FSMs;

deleting an edge from the first set of pruned FSMs which represent service primitives for which there are no counterpart service primitives in the first set of pruned FSMs to form a second set of pruned FSMs; and

deleting an edge in the second set of pruned FSMs which are not within a strongly connected component of the corresponding second pruned FSM that contains the initial state to form a third set of pruned FSMs.

5. A method for generating a gateway system between first and second networks implementing corresponding first and second communication protocols which provide first and second sets of services, wherein each protocol can be represented by a set of at least one finite state machine (FSM), the method comprising the steps of:

determining a common subset of services equal to a subset of the intersection of services provided by the protocols;

determining a first complement service FSM for the first network protocol, wherein the first complement service FSM contains those services provided by the second network protocol that are not characterized in the first network protocol;

pruning the set of second network protocol FSMs to provide only operations corresponding to the services performed by the first complement service FSM to generate a first set of complement network protocol FSMs;

constructing a gateway system employing circuit equivalents of the first and second set of protocol FSMs, the first set of complement protocol FSMs and an interface converter to provide all the input-output services of the first and second networks to users of the first network in communicating through the gateway system;

determining a second complement service FSM for the second network protocol, wherein the second complement service FSM contains those services provided by the first network protocol that are not provided by the second network protocol; and

pruning the set of first network protocol FSMs to provide only operations corresponding to the services performed by the second complement service FSM to generate a second set of complement network protocol FSMs, wherein the step of constructing the gateway system further includes employing a circuit equivalent of the second set of complement protocol FSMs and an interface converter to provide all the input-output services of the first and second networks to users of the first and second network in communicating through the gateway system.

6. A gateway system between first and second networks, each network implementing a protocol, the gateway system comprising:

a first end node connected to the first network, the end node having a protocol circuit and a first complement protocol circuit;

a first communication channel connected to the first end node;

a second end node connected to the second network, the second end node having a protocol circuit;

a second communications channel connected to the second network end node;

a protocol converter connected to the first and second end nodes, the protocol converter having a first interface protocol circuit for communicating with the first end node protocol circuit, and a first interface complement protocol circuit for communicating with the first complement protocol circuit, the protocol converter further having a second interface protocol circuit for communicating with the second end node protocol circuit, and an interface converter connected to the first and second interface protocol circuits and first interface complement protocol circuit, wherein the interface converter translates and routes information between the first interface protocol circuit and the second interface protocol circuit, and between the first interface complement protocol circuit and the second interface protocol circuit to provide the input-output services of the first and second networks to users of the first network in communicating through the gateway system;

a second complement protocol circuit disposed in the second end node, the second complement protocol circuit being connected to the second network and the second communications channel; and

a second interface complement protocol circuit disposed in the protocol converter and being connected to the interface converter and the second communications channel, wherein the interface converter routes information between the first interface protocol circuit and the interface complement protocol circuit, and the second interface protocol circuit and second interface complement protocol circuit to provide input-output services of the first and second networks in communicating through the gateway system.

7. The gateway system of claim 6, wherein the circuits in an end node are contained in a single processor.

8. The gateway system of claim 6, wherein at least two of the circuits in the protocol converter are contained in a single processor.

9. The gateway system of claim 6, wherein the signals between the first protocol circuit and the first interface protocol circuit and between the first complement protocol circuit and the first interface complement protocol circuit are multiplexed on the first communications channel.

10. The gateway system of claim 6, wherein the circuits in the second end node are contained in a single processor.

11. The gateway system of claim 6, wherein at least two of the circuits in the protocol converter are contained in a single processor.

12. The gateway system of claim 6, wherein the signals between the second protocol circuit and second complement protocol circuit and the corresponding second interface protocol circuit and the second interface complement protocol circuit are multiplexed on the second communications channel, respectively.