# US 7,609,623 B2 · Method and system for automatically rerouting data from an overbalanced logical circuit in a data network

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- Number: US 7,609,623 B2
- Document ID: US7609623B2
- Status: Granted
- Kind: B2
- Application number: 10/745,116
- Filed: 2003-12-23
- Published: 2005-06-23
- Granted: 2009-10-27
- Earliest claimed: 2003-12-23
- Assignees: AT&T Intellectual Property I, L.P.
- Inventors: William Taylor; David Massengill; John Hollingsworth
- Web page: https://patentgrep.com/patent/US7609623B2

## CPC

- H04L 47/16: {in connection oriented networks, e.g. frame relay}
- H04L 12/2854: {Wide area networks, e.g. public data networks}
- H04L 41/0654: using network fault recovery (ring fault isolation or reconfiguration in loop networks without recovery actions by a network management system H04L12/437)
- H04L 43/0817: by checking functioning
- H04L 45/10: {Routing in connection-oriented networks, e.g. X.25 or ATM}
- H04L 45/28: using route fault recovery
- H04L 47/122: by diverting traffic away from congested entities
- H04L 47/33: using forward notification
- H04L 69/40: for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection (management of faults, events, alarms or notifications in data switching networks H04L41/06)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A method and system are provided for automatically rerouting data from an overbalanced logical circuit in a data network. Status information is received for a logical circuit communicating data in the data network. The status information may include a forward explicit congestion notification (“FECN”) and a backward explicit congestion notification (“BECN”) indicating an overbalanced condition in the logical circuit. An overbalanced condition is indicative of network congestion in the logical circuit. A logical failover circuit including an alternate communication path for communicating the data in the overbalanced logical circuit is then identified. The data in the overbalanced logical circuit is rerouted to the logical failover circuit without manual intervention. After rerouting the data to the logical failover circuit, a determination is made as to whether the overbalanced condition in the logical circuit has been cleared. If it is determined that the overbalanced condition in the logical circuit has been cleared, then the data from the logical failover circuit is rerouted to the logical circuit in the data network without manual intervention.

## Claims

### Claim 1

A method of automatically rerouting data from an overbalanced logical circuit in a data network, the method comprising:
receiving status information for a logical circuit in the data network, wherein the logical circuit is identified by a first logical circuit identifier, the logical circuit comprising a communication path for communicating data;
determining an overbalanced condition in the logical circuit based on the status information, wherein the overbalanced condition is indicative of congestion in the logical circuit;
identifying a logical failover circuit comprising an alternate communication path for communicating the data in the overbalanced logical circuit, wherein identifying the logical failover circuit comprising the alternate communication path for communicating the data comprises identifying a currently unused logical connection for communicating the data;
prior to rerouting the data from the logical circuit to the logical failover circuit, renaming a second logical circuit identifier of the logical failover circuit to the first logical circuit identifier of the logical circuit and storing the logical circuit identifier changes to a database as reroute data;
rerouting the data to the logical failover circuit without manual intervention;
after rerouting the data to the logical failover circuit, determining whether the overbalanced condition in the logical circuit has been cleared; and
if the overbalanced condition in the logical circuit has been cleared, then rerouting the data from the logical failover circuit to the logical circuit in the data network without manual intervention, wherein rerouting the data from the logical failover circuit to the logical circuit in the data network without manual intervention comprises:
retrieving the reroute data from the database, and
restoring original logical identifers to the logical failover circuit.

### Claim 2 (depends on 1)

The method of claim 1, wherein identifying the logical failover circuit comprising the alternate communication path for communicating the data comprises:
identifying a logical connection in the logical circuit;
based on an identification of the logical connection, determining a first end and a second end of the logical circuit in the data network; and
determining the logical failover circuit comprising a communication path including the first end and the second end.

### Claim 3 (depends on 1)

The method of claim 1, wherein determining the overbalanced condition in the logical circuit comprises determining an overbalanced condition in a logical connection in the logical circuit.

### Claim 4 (depends on 1)

The method of claim 1, wherein the logical failover circuit comprises a dedicated failover logical connection in a failover data network.

### Claim 5 (depends on 1)

The method of claim 1, wherein the first logical circuit identifier is a data link connection identifier (DLCI).

### Claim 6 (depends on 1)

The method of claim 1, wherein the first logical circuit identifier is a virtual path/virtual circuit identifier (VPI/VCI).

### Claim 7 (depends on 2)

The method of claim 2, wherein the logical connection comprises a network-to-network interface.

### Claim 8 (depends on 1)

The method of claim 1, wherein the logical failover circuit is a permanent virtual circuit.

### Claim 9 (depends on 1)

The method of claim 1, wherein the logical failover circuit is a switched virtual circuit.

### Claim 10 (depends on 1)

The method of claim 1, wherein the data network is a frame relay network.

### Claim 11 (depends on 1)

The method of claim 1, wherein the data network is an asynchronous transfer mode (ATM) network.

### Claim 12 (depends on 1)

The method of claim 1, wherein the status information comprises a forward explicit congestion notification.

### Claim 13 (depends on 1)

The method of claim 1, wherein the status information comprises a backward explicit congestion notification.

### Claim 14

A system for automatically rerouting data from an overbalanced logical circuit in a data network, the system comprising:
a network device for communicating status information for a logical circuit in the data network, wherein the logical circuit is identified by a first logical circuit identifier, the logical circuit comprising a communication path for communicating data;
a logical element module, in communication with the network device, for receiving the status information for the logical circuit in the data network; and
a network management module, in communication with the logical element module, for:
requesting the status information from the logical element module;
determining an overbalanced condition in the logical circuit based on the status information, wherein the overbalanced condition is indicative of congestion in the logical circuit;
identifying a logical failover circuit comprising an alternate communication path for communicating the data in the overbalanced logical circuit, wherein the alternate communication path comprises at least one currently unused logical connection in the data network;
prior to rerouting the data from the logical circuit to the logical failover circuit, renaming a second logical circuit identifier of the logical failover circuit to the first logical circuit identifier of the logical circuit and storing the logical circuit identifier changes to a network database as reroute data;
rerouting the data to the logical failover circuit without manual intervention;
after rerouting the data to the logical failover circuit, determining whether the overbalanced condition in the logical circuit has been cleared; and
if the overbalanced condition in the logical circuit has been cleared, then rerouting the data from the logical failover circuit to the logical circuit in the data network without manual intervention, wherein rerouting the data from the logical failover circuit to the logical circuit in the data network without manual intervention comprises:
retrieving the reroute data from the database, and
restoring original logical identifiers to the logical failover circuit.

### Claim 15 (depends on 14)

The system of claim 14, wherein the network management module in identifying the logical failover circuit comprising the alternate communication path for communicating the data, is operative to:
identify a logical connection in the logical circuit;
based on an identification of the logical connection, access the network database to determine a first end and a second end of the logical circuit in the data network; and
determine the logical failover circuit comprising a communication path including the first end and the second end.

### Claim 16 (depends on 15)

The system of claim 15, wherein the communication path including the first end and the second end comprises the at least one currently unused logical connection in the data network.

### Claim 17 (depends on 14)

The system of claim 14, wherein the network management module, in determining the overbalanced condition in the logical circuit, is operative to determine the overbalanced condition in a logical connection in the logical circuit.

### Claim 18 (depends on 14)

The system of claim 14, wherein the logical failover circuit comprises a dedicated failover logical connection in a failover data network.

### Claim 19 (depends on 14)

The system of claim 14, wherein the first logical circuit identifier is a data link connection identifier (DLCI).

### Claim 20 (depends on 14)

The system of claim 14, wherein the first logical circuit identifier is a virtual pathlvirtual circuit identifier (VPI/VCI).

### Claim 21 (depends on 15)

The system of claim 15, wherein the logical connection comprises a network-to-network interface.

### Claim 22 (depends on 14)

The system of claim 14, wherein the logical failover circuit is a permanent virtual circuit.

### Claim 23 (depends on 14)

The system of claim 14, wherein the logical failover circuit is a switched virtual circuit.

### Claim 24 (depends on 14)

The system of claim 14, wherein the data network is a frame relay network.

### Claim 25 (depends on 14)

The system of claim 14, wherein the data network is an asynchronous transfer mode (ATM) network.

### Claim 26 (depends on 14)

The system of claim 14, wherein the status information comprises a forward explicit congestion notification.

### Claim 27 (depends on 14)

The system of claim 14, wherein the status information comprises a backward explicit congestion notification.