Method and system for shortcut routing over public data networks

• US 5,583,996 A
• Filed: 03/16/1993
• Issued: 12/10/1996
• Est. Priority Date: 03/16/1993
• Status: Expired due to Term

• Current Assignee: TTI Inventions A LLC (Intellectual Ventures LLC)
• Original Assignee: Bell Communications Research, Inc. (Telefonaktiebolaget LM Ericsson)
• Inventors: Tsuchiya, Paul F.
• Primary Examiner(s): Bowler, Alyssa H.
• Assistant Examiner(s): DAVIS JR, WALTER D
• Application Number:
  US08/033,638
• Time in Patent Office: 1,365 Days
• Field of Search: 395/800, 395/200, 395/325, 364/DIG. 1, 340/827, 340/825.52, 370/94.1, 370/58.3, 370/60
• US Class Current: 709/218
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A system and method are disclosed for transmitting a packet from a source node S in a first stub 300 to a destination node D in a second stub 306 of an internet communications network 200. The first stub 300 is connected with a public data network (PDN) 210 by a first access point node Ra and the second stub 306 is connected with the PDN 210 by a second access point node Rd. The first access point node Ra, writes its PDN subnetwork address in the packet. The first access point node Ra then transmits the packet via a sequence of one or more intermediary access point nodes Rb, Rc on a base path until the packet reaches the second access point node Rd. The second access point node Rd receives the packet via the base path. The second access point node Rd stores the PDN subnetwork address of the first access point node Ra (contained in the packet) in an entry 131 of shortcut table 130 maintained at the second access point node Rd. Thereafter, the second access point node Rd can transmit a second packet back to the first access point node Ra by transmitting the packet to the first access point node Ra using the PDN subnetwork address of the first access point node Ra stored in the shortcut table entry 131.

Claims

1. In a communications network comprising a backbone subnetwork including a base path, a plurality of stubs each having a plurality of nodes assigned internet addresses and including at least one access point node that connects said each stub with the backbone subnetwork, and means for providing individual shortcut paths between any two access point nodes, a method for transmitting a packet from a first access point node that connects a first stub containing a source node of the packet with said backbone subnetwork to a second access point node that connects a second stub containing a destination node of the packet with said backbone subnetwork, wherein said first access point node maintains a shortcut table and a base path table, said method comprising the steps of:

at said first access point node, if an entry exists in said shortcut table maintained at said first access pint node, which entry corresponds to the internet address of the destination node of said packet, transmitting a backbone subnetwork address of said first access point node in said packet from said first access point node to said second access point node via a shortcut path using a backbone subnetwork address of said second access point node stored in a retrieved shortcut table entry instead of using said base path,

if no shortcut table entry exists, transmitting a backbone subnetwork address of said first access point node in said packet from said first access point node via said base path to said second access point node, and

at said second access point node, receiving said packet and storing said backbone subnetwork address of said first access point node contained in said packet in an entry of a shortcut table maintained at said second access point node, which entry corresponds to the internet address of the source node of said packet,

and said method further comprising the steps of;

at said first access point node, if no entry exists in said shortcut table maintained at said first access point node corresponding to the destination node of said packet, transmitting a flag in said packet indicating that said first access point node does not know a shortcut path to said second access point node, and

at said second access point node, storing said flag contained in said packet in said shortcut table entry maintained at said second access point node.

2. The method of claim 1 further comprising transmitting a second packet from said second access point node to said first node by the steps of:

at said second access point node, if said shortcut table entry corresponding to the internet address of said destination node of said second packet contains a flag indicating that said first access point node does not know a shortcut path to said second access point node, transmitting a backbone subnetwork address of said second access point node in said second packet from said second access point node via said base path to said first access point node, and

at said second access point node, if said shortcut table entry does not contain said flag, transmitting said second packet to said first access point node using said backbone subnetwork address stored in said shortcut table entry as a shortcut path.

3. In a communications network comprising a plurality of stubs each having a plurality of nodes assigned internet addresses and including an access point node, a base path sequentially connecting said access point nodes, each of said access nodes having a base path address, and shortcut direct paths between any two access point nodes, a method for establishing direct intercommunication over a shortcut path between a first access point node that connects a first stub containing a source node transmitting a packet and a second access point node that connects a second stub containing a destination node of the packet, said method comprising the steps of:

at said first access point node, transmitting said packet over said base path through at least one intermediate node to said second access point node,

at said second access point node, receiving said packet via said base path and storing the base path address of said first access point node contained in said packet in an entry of a shortcut table maintained at said second access point node, whereby said second access point node has learned the shortcut path and has stored it in said shortcut table for future use in communications between said first and second access point nodes of packets to be transmitted between said source and destination nodes, said entry of said shortcut table corresponding to the internet address of the source node of said packet;

transmitting a second packet from said second access point node to said first access point node via the shortcut path between said first and second access point nodes using said base path address of said first access point node stored in said shortcut table entry instead of transmitting said second packet via said base path, and

wherein said communications network is reconfigured such that a third access point node connects said first stub with said base path but said first access point node no longer connects said first stub with said base path, said method further comprising the steps of;

receiving said second packet at said first access point node,

at said first access point node, writing the base path address of said second access point node and a flag indicating that said second access point node does not know a shortcut path to said third access point node in said second packet, and

transmitting said second packet from said first access point node to said third access point node via said base path.

4. In a communications network comprising a backbone subnetwork and a plurality of stubs each of which is connected with said backbone network by an access point node, one or more of said access point nodes including a memory for storing a base path table defining a base path in said backbone subnetwork to each other access point node and a shortcut table with a shortcut path entry defining a shortcut path in said subnetwork to one or more other access points, the method for causing a specific access point node to learn the shortcut path between said specific access point node and another access point node and storing an identification of said shortcut path in the shortcut table of said specific access node for future use of said shortcut path in communications of packets between said specific access point node and said another access point node, said method comprising the steps of:

transmitting a packet from said another access point node to said specific access point node over a base path through a least one intermediate node, and

at said specific access point node, receiving said packet via said base path and storing the base path address of said another access point node contained in said packet in an entry of said shortcut table maintained at said specific access point node,

whereby subsequent transmission from said specific access point node to said another access point node occurs via said shortcut path in said backbone network if a shortcut entry corresponding to said another access point node exists in said shortcut table at said specific access point node and subsequent transmission to said another access point node occurs via a base path defined in said base path table at said specific access point node if no shortcut entry exists in said shortcut table at said specific access point node.