Method of tracing the root of virtual connections

• US 6,563,795 B1
• Filed: 04/16/1999
• Issued: 05/13/2003
• Est. Priority Date: 04/11/1995
• Status: Expired due to Term

• Current Assignee: RPX Clearinghouse LLC (RPX Corporation)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Vickers, Richard, Methiwalla, Asghar Ebrahim, Gruber, John Gerald
• Primary Examiner(s): Nguyen, Chau
• Assistant Examiner(s): DUONG, DUC T
• Application Number:
  US09/292,356
• Time in Patent Office: 1,488 Days
• Field of Search: 370/241,241.1,242,248,249,428 714/1,2,4 340/825.01,3.43
• US Class Current: 370/248
• CPC Class Codes: H04J 3/12 Arrangements providing for calling or supervisory signals
• CPC Class Codes: H04L 2012/562 Routing
• CPC Class Codes: H04L 2012/5625 Operations, administration and maintenance [OAM]
• CPC Class Codes: H04L 2012/5636 Monitoring or policing, e.g. compliance with allocated rate, corrective actions
• CPC Class Codes: H04L 2012/5652 Cell construction, e.g. including header, packetisation, depacketisation, assembly, reassembly
• CPC Class Codes: H04L 43/50 Testing arrangements
• CPC Class Codes: H04Q 11/0478 Provisions for broadband connections

Abstract

A telecommunications network such as an ATM, Frame Relay or packet based network will be better managed by identifying nodes through which a virtual connection is routed between two end nodes. A new method of tracing the nodes on the route includes sending trace cells downstream of a monitoring node toward one or both end nodes. Each downstream node either loops back a trace cell identifying itself to the monitoring node or forwards the trace cell further. A plurality of trace cells sent along the route identify nodes located thereon. In one embodiment, the trace cell is an extension of the ATM FMOAM cell (ATM Fault Management OAM cell) specified for loopback functions.

Claims

1. In a telecommunications network which is holding a virtual connection between two end nodes by a route consisting of one or more links, a method of enabling the identification of an error in a link of the route comprising the steps of:

sending from a monitoring node, a first cell downstream towards an end node, the first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

forwarding, at each node downstream on the route, the first cell downstream if the identification of the node does not match the default value, and

sending, from each node downstream to the monitoring node, a second cell having the loopback indication unset and carrying its own identification, so that an identification of the nodes on the route is made to the monitoring node.

2. The method of claim 1 wherein the source ID field includes the identification of the monitoring node.

3. A network for holding a virtual connection between two end nodes by a route consisting of one or more links, the network including apparatus for tracing the route, the apparatus comprising:

means for sending from a monitoring node, a first cell downstream towards an end node, the first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

means for forwarding, at each node downstream on the route, the first cell downstream if the identification of the node does not match the default value, and

means for sending from each node downstream to the monitoring node, a second cell having the loopback indication unset and carrying its own identification, so that an identification of the nodes on the route is made to the monitoring node.

4. The network of claim 3 wherein the source ID field includes the identification of the monitoring node.

5. In a network node for maintaining a virtual connection in a route consisting of one or more links, a method of causing a tracing of the route, the method comprising the steps of:

receiving from a monitoring node, a first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

forwarding, the first cell downstream if the identification of the network node does not match the default value, and

sending to the monitoring node, a second cell having the loopback indication unset and carrying the identification of the network node, so that an identification of the network node is made to the monitoring node.

6. The method of claim 5 wherein the source ID field includes the identification of the monitoring node.

7. A network node for maintaining a virtual connection in a route consisting of one or more links and including apparatus for tracing of the route, the apparatus comprising:

means for receiving from a monitoring node, a first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

means for forwarding, the first cell downstream if the identification of the network node does not match the default value, and

means for sending to the monitoring node, a second cell having the loopback indication unset and carrying the identification of the network node, so that an identification of the network node is made to the monitoring node.

8. The network node of claim 7 wherein the source ID field includes the identification of the monitoring node.

9. In a monitoring node, a method of building a list of nodes in a route consisting of one or more links in a network which is holding a virtual connection between two end nodes, the method comprising the steps of:

sending a first cell downstream towards an end node, the first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

receiving, from each node downstream before and including a default value identified node, an additional cell having the loopback indication unset and carrying the identification of the node from which the additional cell is received; and

storing the identifications of the nodes in the route.

10. The method of claim 9 wherein the source ID field includes the identification of the monitoring node.

11. A monitoring node for building a list of nodes in a route consisting of one or more links in a network which is holding a virtual connection between two end nodes, the node comprising:

means for sending a first cell downstream towards an end node, the first cell having a loopback location set to a default value and a loopback indication set to indicate a loopback function, the first cell also including a source ID field;

means for receiving, from each node downstream before and including a default value identified node, an additional cell having the loopback indication unset and carrying the identification of the node from which the additional cell is received; and

means for storing the identifications of the nodes in the route.

12. The monitoring node of claim 11 wherein the source ID field includes the identification of the monitoring node.