Multiplex communications – Pathfinding or routing – Switching a message which includes an address header
Reexamination Certificate
1997-07-16
2001-02-27
Olms, Douglas W. (Department: 2732)
Multiplex communications
Pathfinding or routing
Switching a message which includes an address header
C370S237000, C370S232000
Reexamination Certificate
active
06195354
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to packet switching networks and, more particularly, to route selection and path balancing in connection-oriented packet switching networks.
In a connection-oriented packet switching network, an example of which includes an X.25 packet network (as well as an Asynchronous Transfer Mode (ATM) network, which can operate in a connection-oriented environment), virtual circuits or connections are established before traffic can be sent on them. A connection-oriented packet switching network consists of switching nodes interconnected by transmission link groups, each of which comprises any number of parallel transmission links. When the network establishes a connection, the network selects a route that may go through a number of intermediate switching nodes. The route consists of active traffic paths established on the transmission link groups connecting the switching nodes along the route. Each traffic path is established on one transmission link between a pair of nodes.
Within each transmission link group, the network traffic among transmission links should be balanced to enhance congestion management capability, fault recovery, and quality of service to name a few. Decisions as to how to balance paths within a transmission link group may be made during route selection by a single node such as the source node. One disadvantage with this approach is that the view any single switching node has of the entire network is likely outdated. As a result of network delay, the node may be unaware of the establishment of new connections and the termination of old connections since the last update of the switching node.
A better alternative is to make path balancing decisions at transmission links as paths are being established on each transmission link group. Although basing balancing decisions as paths are being established uses up-to-date information about other active paths on the transmission link group, terminating connections or adding new transmission links to transmission link groups may cause an imbalance if path balancing decisions are made only when new paths are established.
Traffic may also become unbalanced when a transmission link fails. When a link fails, traffic from the failed link may be rerouted to other links in the transmission link group. Unless traffic is rerouted to that link upon its restoration to service, traffic may not be balanced among the links in the transmission link group.
It is, therefore, desirable to redistribute established, active traffic paths in transmission link groups in a connection-oriented packet switching network to balance the traffic paths among the transmission links in the transmission link groups. It is even more desirable to redistribute established, active paths in a transmission link group to reduce variance in utilization of path resources, such as bandwidth, CPU, and/or memory between links of a group. It is also desirable to redistribute established, active paths in a transmission link group to reduce variance in average utilization of path resources between links of a group on a per link basis.
SUMMARY OF THE INVENTION
This invention meets those needs through a method for redistributing network traffic paths based on comparisons of network resource utilization.
Additional desires and goals will be set forth in part in the following description, and in part will be appreciated by one of ordinary skill in the art from the description, or may be learned by practice of the invention. The desires and goals of the invention will be realized and attained by the elements and combinations in the appended claims.
To achieve the objectives and in accordance with the purpose of the invention, as embodied and broadly described herein, a method consistent with the present invention is provided for distributing traffic paths among a plurality of links in a connection-oriented packet switching network. The network includes a plurality of switching nodes interconnected by a plurality of link groups, each including a plurality of links for carrying traffic paths. The method comprises the steps of comparing a measure of the utilization of a network resource by a first one of the links of a group currently carrying a traffic path with a measure of the utilization of the network resource by a second one of the links of the group; and identifying one of the first or second links as a candidate for carrying the traffic path based on the comparison. Consistent with the present invention, the step of identifying includes the substep of identifying all candidate links for carrying the traffic path, the method further comprising the step of moving the traffic path to a candidate link such that the move reduces variation in the utilization of the network resource by each of the links in the group.
The above desires, other desires, features, and advantages of the present invention will be readily appreciated by one of ordinary skill in the art from the following detailed description of the preferred implementations when taken in connection with the accompanying drawings.
REFERENCES:
patent: 4679189 (1987-07-01), Olson
patent: 4870641 (1989-09-01), Pattavina
patent: 5265091 (1993-11-01), Van Landegem
patent: 5347511 (1994-09-01), Gun
patent: 5398236 (1995-03-01), Hemmady
patent: 5404451 (1995-04-01), Nemirovsky
patent: 5629930 (1997-05-01), Beshai
patent: 5687168 (1997-11-01), Iwata
patent: 5850385 (1998-12-01), Esaki
Ashwood-Smith Peter J.
Fedyk Donald W.
Matas Yair
Skalecki Darek Robert
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Nortel Networks Limited
Olms Douglas W.
Pizarro Ricardo M.
LandOfFree
Route selection for path balancing in connection-oriented... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Route selection for path balancing in connection-oriented..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Route selection for path balancing in connection-oriented... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2560476