JP3427954B2 - MP path search circuit - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a broadcast service application such as broadcasting in a communication network.
The present invention relates to an MP path search circuit for searching for a multipoint (MP) path connecting at least three destination nodes with a branch / concentration. 2. Description of the Related Art In a conventional MP path search circuit of this type, when an MP path search request is received from a user, a destination node is obtained from network configuration information and information on a destination terminal provided by the user, and a network is determined. M from configuration information and destination node information
I was looking for a P pass. [0003] Therefore, there is a problem that much time is required from receiving a search request to responding. Further, in a type of circuit in which a node is added as a search target and an MP path is obtained, the number of nodes to be searched depends on the network scale, so that there is a problem that the calculation time increases in a large-scale network. An object of the present invention is to provide an MP path search circuit capable of shortening a search time. [0005] [Means for Solving the Problems] To achieve the above object, MP path in this onset bright, or search for multi-point (MP) paths for connecting the at least three destination nodes involves branching / concentrator In the search circuit, a network configuration acquisition unit that acquires network configuration information necessary for calculation, a network configuration storage unit that stores the acquired network configuration information, and a minimum cost point point based on the storage information of the network configuration storage unit. (PP) A minimum cost PP path search unit for obtaining a path, a PP path storage unit for storing the obtained minimum cost PP path, a destination node obtaining unit for obtaining a destination node from a user, and a source / destination node obtained based on the obtained destination node. A search target node determining unit for determining a search target node to be searched, and a minimum cost spanner based on information from the search target node determining unit and the PP path storage unit. A minimum-cost spanning-tree search unit for obtaining a spanning tree, a pruning unit for pruning unnecessary branches from the obtained minimum-cost spanning tree, and an MP path output unit for outputting a processing result.
A real-time processing unit that executes processing when a request is received from a user is configured by a search target node determination unit, a minimum cost spanning tree search unit, a pruning unit, and an MP path output unit, and a network configuration acquisition unit and a minimum cost PP path MP path search in which a non-real-time processing unit configured to execute processing periodically or as required by a search unit is configured, and an information storage unit configured to store information required for processing is configured by a network configuration storage unit and a PP path storage unit. A circuit, wherein the search target node is
The decision unit creates a complete graph consisting of only destination nodes.
And input it to the minimum cost spanning tree search unit.
From the minimum cost spanning tree search unit
Get a spanning tree and get the lowest cost spanning tree
Link to the least cost PP path in the complete graph
At the middle of the cost of the minimum cost PP path
We propose an MP path search circuit that uses a located node as a search target node . [0006] [0007] [action] According to the onset Ming, among the processes necessary for the search of the MP path, the minimum cost PP path determined by the network configuration is appropriate periodic or necessary in advance non-real time processing unit Search, and the actual M determined by the destination node
The P path is searched in the real time processing unit when requested by the user, so that the time required for processing after the user requests the MP path search, that is, the search time can be reduced . , Search target
The number of nodes depends on the number of destination nodes.
Since it is no longer dependent on the scale, even if it is applied to a large-scale network,
No increase in switch time. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of a communication network using an MP path. Here, a case where there are three communication nodes is shown.
In the figure, 10-1, 10-2 and 10-3 are communication nodes, 2
0-1, 20-2, and 20-3 are communication links;
30-2, 30-3, 30-4, 30-5, and 30-6 are terminals. Communication nodes 10-1, 10-2, 10-3
Are MP path search circuits 40-1, 40-2, 40-3 for searching MP paths, switches 50-1, 50-2, 50-3 for switching paths, and a copy function unit 60- for copying information. 1, 60-2 and 60-3. Also, each of the communication links 20-1 to 20-
3 is assigned a communication cost in advance. In some cases, the MP path search circuit is not provided in a communication node but is provided in a workstation or the like constituting a terminal. The same applies in that case. FIG. 2 shows an embodiment of an MP path search circuit according to the present invention. In FIG.
2 is a search target node determination unit, 43 is a minimum cost spanning tree search unit, 44 is a pruning unit, 45 is MP
A path output unit, 46 is a network configuration acquisition unit, 47 is a minimum cost point (PP) path search unit, 48 is a network configuration storage unit, and 49 is a PP path storage unit. The destination node acquiring section 41 acquires a destination node from a user. Further, the search target node determination unit 42 determines a search target node to be a search target based on the acquired destination node. Further, the minimum cost spanning tree search unit 43 includes a search target node determination unit 42 and a PP
A minimum cost spanning tree is obtained based on information from the path storage unit 49. Further, the pruning unit 44 prunes unnecessary branches from the minimum cost spanning tree obtained above.
The MP path output unit 45 outputs a processing result. The network configuration acquisition section 46 acquires network configuration information necessary for calculation. The minimum cost PP path search unit 47
Calculates the minimum cost PP path based on the information stored in the network configuration storage unit 48. The network configuration storage unit 48 stores the acquired network configuration information. Further, the PP path storage unit 49 stores the obtained minimum cost PP path. The above-mentioned source / destination node acquisition unit 41, search target node determination unit 42, minimum cost spanning tree search unit 43, pruning unit 44, and MP path output unit 45
Constitutes a real-time processing unit 40a that executes a process when a request is received from a user. Further, the network configuration acquisition unit 46 and the minimum cost PP path search unit 47 constitute a non-real time processing unit 40b that executes a process periodically or as needed. The network configuration storage unit 48 and the PP path storage unit 49
Constitutes an information storage unit 40c for storing information necessary for processing. In the MP path search circuit of the present invention, in order to speed up processing at the time of a request from a user,
The non-real-time processing unit 40b obtains the minimum cost PP path information from the network configuration information in advance, and shortens the processing time in the real-time processing unit 40a that performs processing at the time of request. FIG. 3 shows the flow of processing in the MP path search circuit of the present invention, and here shows a case where a search target node to be described later is added. FIG. 4 is a flowchart of a process for describing a conventional method of determining a search target node, and FIG. 5 is a flowchart of a process for describing a method of determining a search target node in the present invention. FIGS. 6 and 7 show an example of the MP path search according to the present invention. FIG. 6A shows the configuration of the entire communication network, and FIG. FIG. 6 (c) shows the search target nodes obtained by the present invention and the conventional method, respectively. FIG.
7A shows a complete graph in the case of the search target node selected in the present invention, and FIG. 7B shows a finally obtained solution (processing result). Here, the complete graph represents the communication network by nodes included in the communication network and links that directly connect all the nodes to each other. A set of nodes is denoted by V, and a set of links is denoted by V. L, the complete graph G = {V, L}
Notation. The type of adding a search target node is as follows.
As shown in FIG. 6 (a), out of the twelve nodes N1 to N12 constituting the communication network, the source and destination nodes, for example, N1, N
3, N4, N10, and other search target nodes, here N2, N11, are added to form a complete graph as shown in FIG. Is what you want. Note that the accuracy of the solution changes with the addition of the search target node. Also, the broken lines in FIG. 6 (a) indicate the destination nodes N1, N3, N4, N10.
2 shows the minimum cost PP path between them. Next, the operation of this embodiment will be described with reference to FIGS. 3, 6, and 7. FIG. First, as described later, a set A (N2, N11) of search target nodes is obtained (step S1), and in a complete graph of the entire communication network, for example, G = {V, L}, Set A and set D of destination nodes
(N1, N3, N4, N10) and the union O (N1, N
2, the minimum cost PP path is searched for all combinations of nodes included in N2, N3, N4, N10, and N11) (step S2). Next, as shown in FIG. 7A, the complete graph G ′ =
{O, L ′} is created, and a link l ′ (a set L ′ of links)
Are assigned to the individual links that constitute the minimum cost PP path (step S3), and the minimum cost spanning tree T ′ in the complete graph G ′ is determined (step S4). Next, the link (the bold line in FIG. 7A) of the obtained minimum cost spanning tree T 'is replaced with the minimum cost PP path in the complete graph G, and the complete graph G
Is obtained (Step S5), the minimum cost spanning tree T '' is obtained from the subgraph G '' (Step S6), and a branch other than the source / destination node as a leaf (for example, N
10-N11) to obtain the link of the final solution T as shown by the bold line in FIG.
7). As can be seen from the above description, the smaller the number of nodes to be searched, the smaller the amount of calculation, and the calculation time for real-time processing is shortened. Next, a method of determining a search target node in the present embodiment will be described in comparison with a conventional case. That is, conventionally, as shown in FIG.
In the complete graph G = {V, L} of the entire communication network, a minimum cost PP path is searched for all combinations of the set D (N1, N3, N4, N10) of destination nodes (step SP1), and FIG. As shown in b), a complete graph Ga ′ = {D, La ′} composed only of the originating and terminating nodes is created, and the link la ′ (the individual links constituting the link set La ′) has the minimum cost PP. A path cost is assigned (step SP2), and a minimum cost spanning tree Ta 'in the complete graph Ga' is obtained (step SP2).
3). Next, the link (the thick line in FIG. 6B) of the minimum cost spanning tree Ta ′ obtained above is replaced with the minimum cost PP path in the complete graph G, and the complete graph G
Is obtained (step SP4), and the minimum cost spanning tree Ta '' is obtained from the subgraph Ga '' (step SP5). Next, in the tree Ta ″, branches having leaves other than the source / destination nodes as leaves are pruned to obtain a tree Ta (step SP6), and a set D of nodes constituting the tree Ta is obtained.
From step 2, all nodes other than the destination node are selected as search target nodes (here, N2, N7, N11) (step SP7). Therefore, the number of search target nodes greatly increases as the number of nodes on the minimum cost PP path between the destination and destination nodes and the scale of the network increase. On the other hand, in the present invention, as shown in FIG. 5, the same operation as in the conventional case is performed in steps SP1 to SP3, but in step SP4 ', the link of the minimum cost spanning tree Ta' is represented by a complete graph G. Is selected as a search target node (here, N2 and N11) when the minimum cost PP path is replaced with the minimum cost PP path. Therefore, the maximum number of nodes to be searched is (number of sending / receiving nodes) -1 and does not depend on the scale of the network. Further, when the number of nodes on the minimum cost PP path between the sending and receiving nodes is as large as two or more, the calculation time of the real-time processing is more advantageous than in the related art. [0033] As described above, according to the present invention, according to the present onset Akira,
Of the processing required for MP path search, the minimum cost PP path determined by the network configuration is searched in advance in the non-real-time processing unit periodically or as needed, and for the actual MP path determined by the destination node, by that none to search when there is a request from the user in the real time processing unit, time required for processing after an search request MP path from the user, i.e. can reduce the search time and search nodes Is the number of destination nodes
And no longer depend on the size of the network.
And increase search time even when applied to large-scale networks
There is no. [0034]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing an example of a communication network using an MP path. FIG. 2 is a configuration diagram showing an embodiment of an MP path search circuit of the present invention. FIG. 4 is a flowchart of a process for explaining a conventional method of determining a search target node. FIG. 5 is a flowchart of a process for describing a method of determining a search target node in the present invention. 6 is an explanatory diagram showing an example of an MP path search according to the present invention. FIG. 7 is an explanatory diagram showing an example of an MP path search according to the present invention. [Description of References] 40a: real-time processing unit; Real-time processing unit, 40
c: Information storage unit, 41: Destination node acquisition unit, 42: Search target node determination unit, 43: Minimum cost spanning tree search unit, 44: Pruning unit, 45: MP path output unit, 46: Network configuration acquisition unit, 47: minimum cost PP path search unit; 48: network configuration storage unit; 49: PP path storage unit.

Continuation of front page (72) Inventor Tatsuo Sawada Nippon Telegraph and Telephone Corporation, 1-6-1, Uchisaiwaicho, Chiyoda-ku, Tokyo (56) References Bernard M. Waxman, Routing of Multipoint in Connections, IEEE Journal of selected areas in communications, December 1988, Vol. 6, No. 9, pp. 1617-1622 1995 IEICE General Conference B-825 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/56 H04L 12/28 H04L 12/46

Claims (1)

(57) [Claim 1] In an MP path search circuit for searching a multipoint (MP) path connecting at least three source / destination nodes with branch / concentration, network configuration information required for calculation , A network configuration storage unit for storing the obtained network configuration information, and a minimum cost PP path search for obtaining a minimum cost point point (PP) path based on information stored in the network configuration storage unit Unit, a PP path storage unit that stores the obtained minimum cost PP path, a destination node obtaining unit that obtains a destination node from a user, and a search that obtains a search target node to be searched based on the obtained destination node. A target node determination unit; and a minimum cost spanning for obtaining a minimum cost spanning tree based on information from the search target node determination unit and the PP path storage unit. A tree search unit, a pruning unit that prunes unnecessary branches from the obtained minimum cost spanning tree, and an MP path output unit that outputs a processing result. Cost spanning tree search unit, pruning unit and M
A real-time processing unit that executes processing when a request is received from a user by a P-path output unit; a non-real-time processing unit that executes processing periodically or as needed by a network configuration acquisition unit and a minimum cost PP path search unit MP path search circuit comprising a processing unit, and an information storage unit for storing information required for processing by the network configuration storage unit and the PP path storage unit
And the search target node determination unit is configured only with the destination node.
Create a complete graph that is
-Input to the search unit and
The minimum cost spanning tree from the
Minimize cost spanning tree links in a complete graph
When the cost PP path is replaced, the minimum cost PP path
Nodes located in the middle of the
An MP path search circuit, characterized in that: