Computer-aided design and analysis of circuits and semiconductor – Nanotechnology related integrated circuit design
Reexamination Certificate
2002-11-15
2004-10-19
Do, Thuan (Department: 2825)
Computer-aided design and analysis of circuits and semiconductor
Nanotechnology related integrated circuit design
C370S228000, C716S030000, C716S030000, C716S030000, C716S030000
Reexamination Certificate
active
06807653
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a recovery path designing circuit, a method and a program thereof for designing an alternative path in a pre-establishing-type failure-detected end switching system.
DESCRIPTION OF THE RELATED ART
As a conventional communication network designing method, for example, there has been proposed a recovery path designing method for a path end switching system in which a path is switched at the origin thereof by Yijun Xiong and Lorne Mason, “Restoration strategies and spare capacity requirements in self-healing ATM networks”, INFOCOM'97, April 1997.
FIG. 1
is a diagram showing an example of a result of design obtained on the basis of the conventional designing method. In
FIG. 1
, reference marks n
1
to n
8
represent nodes, and reference marks p
1
and p
2
denote paths. The p
1
is a primary path, and the p
2
is a recovery path. Each line between adjacent two nodes represents a link. These links are expressed as link (n
1
, n
2
) and the like. While depicted with one line in
FIG. 1
, each link is bi-directional. For example, the link (n
1
, n
2
) includes two links in the opposite directions: from n
1
to n
2
; and from n
2
to n
1
. It should be noted that any number of links may be present between adjacent two nodes.
In this example in
FIG. 1
, the alternative path p
2
is set for the primary path p
1
. In case of actual failure, the node n
1
at one end of the path is informed of the failure, and switches the route from the primary path p
1
to the alternative path p
2
. For example, when failure occurs on the link (n
3
, n
4
), the node n
3
detects the failure and sends a message of the failure occurrence to the node n
1
. When receiving the message, the node n
1
switches the route to the recovery path p
2
.
In the following, another prior arts related to the present invention are mentioned. In Japanese Patent Application Laid-Open No. 2000-22750, the applicant of the present invention has disclosed a technique, in a multipoint communication network designing method, to design a link capacity and a node capacity in a communication network on the premise of variation of traffic demands. This application does not directly teach, but touches on, the recovery path designing method for a pre-establishing-type failure detecting end switching system.
In Japanese Patent Application Laid-Open No. HEI 11-215124, the applicant has disclosed a technique to accommodate traffic even if demand patterns are changed to some extent.
In Japanese Patent Application Laid-Open No. 2001-36574, the applicant has disclosed a technique, when communication between an ingress node and an egress node of a network is performed on a communication line having tree structure, to build a communication link having tree structure with the minimum number of branches, which accommodates paths between a given entrance node and exit node.
Additionally, in Japanese Patent Application Laid-Open No. 2002-57676, the applicant has disclosed a technique to permit arbitrary communication within a given range by providing the amount of data traffic flowing in through an ingress node and the amount of data traffic flowing out from an egress node.
Compared to the path end switching system, in a failure-detected end switching system, there is no need to notify a failure occurrence because a node that has detected the failure switches a route, thus enabling faster failure recovery. However, a plurality of recovery paths are necessary for one primary path. Thereby, unless the recovery paths are set so as to effectively share the resources for recovery, a great amount of resources is to be required.
The method proposed by Yijun Xiong and Lorne Mason is premised on the path end switching system. In this method, it is impossible to design recovery paths on the basis of failure-detected end switching, and an efficient recovery path designing method has been sought.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a recovery path designing circuit, a method and a program thereof capable of reducing necessary resources as much as possible when forming recovery paths on a pre-establishing-type failure-detected end switching system.
According to a first aspect of the present invention, for achieving the object mentioned above, there is provided a recovery path designing circuit for designing recovery paths in a multipoint communication network including a plurality of nodes and links that connect the nodes, which employs a pre-establishing-type failure-detected end switching system in which alternate paths for respective primary paths are pre-established and a node that has detected a failure switches the route from a primary path to a recovery path, comprising:
an optimization reference generating means for setting an objective function to minimize a link cost;
a recovery path forming condition generating means for generating a constraint expression to form a recovery path from a switching start node to an Egress node;
a link capacity calculating condition generating means for generating a constraint expression to calculate a link capacity required of the respective links;
a link accommodating condition generating means for generating a constraint expression to accommodate the link capacity within a range of a given link capacity;
a forbidden link and node setting condition generating means for generating constraint expressions to set at least one unavailable forbidden node and link with respect to each recovery path; and
an optimizing means for solving integer programming problems expressed by the objective function set by the optimization reference generating means and constraint expressions generated by the recovery path forming condition generating means, the link capacity calculating condition generating means, the link accommodating condition generating means, and the forbidden link and node setting condition generating means.
According to a second aspect of the present invention, in the first aspect, the optimization reference generating means sets an objective function to minimize a link metric and a path metric in addition to the minimization of the link cost.
According to a third aspect of the present invention, there is provided a recovery path designing circuit for designing recovery paths in a multipoint communication network including a plurality of nodes and links that connect the nodes, which employs a pre-establishing-type failure-detected end switching system in which alternate paths for respective primary paths are pre-established and a node that has detected a failure switches the route from a primary path to a recovery path, comprising:
an optimization reference generating means for setting an objective function to minimize a maximum link load;
a recovery path forming condition generating means for generating a constraint expression to form a recovery path from a switching start node to an Egress node;
a link capacity calculating condition generating means for generating a constraint expression to calculate a link capacity required of the respective links and the maximum link load;
a link accommodating condition generating means for generating a constraint expression to accommodate the link capacity within a range of a given link capacity;
a forbidden link and node setting condition generating means for generating constraint expressions to set at least one unavailable forbidden node and link with respect to each recovery path; and
an optimizing means for solving integer programming problems expressed by the objective function set by the optimization reference generating means and constraint expressions generated by the recovery path forming condition generating means, the link capacity calculating condition generating means, the link accommodating condition generating means, and the forbidden link and node setting condition generating means.
According to a fourth aspect of the present invention, in one of the first to third aspects, the link capacity calculating condition generating means generates a cons
Do Thuan
Ostrolenk Faber Gerb & Soffen, LLP
LandOfFree
Recovery path designing circuit, method and program thereof does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Recovery path designing circuit, method and program thereof, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Recovery path designing circuit, method and program thereof will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3313870