Node initiating XID exchanges over an activated link including an exchange of sets of binding signals between nodes for establishing sessions

• US 5,109,483 A
• Filed: 06/15/1987
• Issued: 04/28/1992
• Est. Priority Date: 06/15/1987
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: International Business Machines Corporation
• Inventors: Rafalow, Lee M., Pollard, Melinda R., Baratz, Alan E., Grover, George A., Pozefsky, Diane P., Drake, John E. Jr., Gray, James P.
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): Mohamed, Ayni
• Application Number:
  US07/062,280
• Time in Patent Office: 1,779 Days
• Field of Search: 364/200 MS File, 364/ 900 MS File
• US Class Current: 709/227
• CPC Class Codes: H04L 69/00 Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass networks security protocols H04L9/40; wireless communication networks H04W

Abstract

Enhanced type 2.1 nodes for SNA networks provide network routing of information between non-adjacent network nodes and program-to-program linkage across the network. These nodes are called "advanced peer to peer networking" (abbreviated APPN) nodes. Network state information, describing the topology and resources of the network is disseminated betweeen APPN nodes by a first data link control exchange of identification (XID) information indicating node type (and thereby distinguishing APPN nodes from other nodes) and other exchanges conducted over a newly defined control point to control point (abbreviated CP--CP) session having a message architecture unique to APPN type nodes. The XID exchange is conducted whenever a link between nodes is activated, and when the exchanging nodes are both APPN, and if both are available to participate in as CP--CP session, they automatically engage in a second exchange of session binding signals which establish a pair of sessions between the nodes. By internal conventions, the node components which use the session pair for exchanging their network state information adapt the sessions to be used in simplex modes with one session flowing from one node to the other and the other flowing in reverse from the other node to the one node. Within these sessions, for the sake of efficiency, communications are not directly acknowledged. Instead, a process transparent to the sessions monitors for link failure and upon such occurrence notifies all affected components to terminate their use of the session and deactivate the session.

Claims

1. A method of disseminating network state information (NSI) in a computer network containing nodes of a predetermined type, each of said nodes being capable of sustaining NSI exchange sessions only with other nodes of like type, said method being practiced at each of two nodes at opposite ends of a link and comprising the steps of:

sending a first set of signals to the other node upon activation of the link, said first set of signals indicating the availability of the sending node to participate in an NSI exchange session;

processing signals received from the other node to determine if both nodes are available for participation in an NSI exchange session and whether the other node is a service provider;

sending a second set of NSI exchange session-establishing signals to the other node if both nodes are available for an NSI exchange session and at least one of the nodes is a service provider;

sending a third set of signals to the other node on the established session to provide the other node with information as to the capabilities of the sending node; and

making said NSI exchange session available to transaction programs running at the node.

2. A method as defined in claim 1 wherein each of the nodes at opposite ends of the link independently establishes a session flowing from the node to the other node.

3. A method as defined in claim 2 wherein a node receiving information from the other node need not directly acknowledge the receipt of that information.

4. A method of disseminating network state information (NSI) in an SNA computer network containing Type 2.1 nodes, each of said nodes being capable of sustaining NSI exchange sessions, referred to hereafter as CP--CP sessions, only with other Type 2.1 nodes, said method being practiced at each of two nodes at opposite ends of a link and comprising the steps of:

sending a first set of signals to the other node upon activation of the link, said first set of signals indicating the availability of the sending node to participate in a CP--CP session;

processing signals received from the other node to determine if both nodes are available for participation in a CP--CP session and whether the other node is a service provider;

sending a second set of CP--CP session-establishing signals to the other node if both nodes are available for such a session and at least one of the nodes is a service provider;

sending a third set of signals to the other node on the established CP--CP session to provide the other node with information relating to the capabilities of the sending node; and

making said CP--CP session available to transaction programs running at the node.

5. A method as defined in claim 4 wherein the third set of signals identifies the sending node either as an end node incapable of providing routing services to other nodes or a network node capable of providing such services.