JP4272614B2 - Pass release method - Google Patents

Description

The present invention relates to a path open way.

  When one or more switches are on the path from a transmitting terminal that transmits data to a receiving terminal that receives data, a communication path is established from the transmitting terminal to the receiving terminal via the switch, and the communication Connection-type networks that transmit data via a communication path are widely used.

And the photonic network (refer nonpatent literature 1) comprised by the switch corresponding to the communication by light is implement | achieved. As a communication technology using light, for example, there is a SDH / SONET (Synchronous Digital Hierarchy / Synchronous Optical NETwork) standard (see Non-Patent Document 2). ) (See Non-Patent Document 3).
Katsumi Emura et al., “Key technologies for photonic networks”, [online], [October 18, 2004 search], Internet <URL: http://www.ieice.org/jpn/books/kaishikiji/ 200205 / 200205_3-1.html> Alcatel networks, “Alcatel 1354 RM Network Manager for SDH / SONET and Optical Networks”, [online], [October 18, 2004 search], Internet <URL: http://www.alcatel.co.jp/doctypes /opgdatasheet/pdfa4/1354RM_3.pdf> IETF, “Generalized Multi-Protocol Label Switching Architecture”, [online], [October 18, 2004 search], Internet <URL: http://www.ietf.org/internet-drafts/draft-ietf-ccamp -gmpls-architecture-07.txt>

  In the path control based on the conventional signaling protocol, when setting a communication path between the data transmitting terminal and the receiving terminal, it is necessary to send a setting instruction to all the switches that pass therethrough. For this reason, the load on the network related to path control, such as the time required to complete path setting increases with the increase in the number of nodes that pass through, and the control message increases and the server load increases as the number of paths increases. There was a problem that it was expensive.

  Accordingly, the main object of the present invention is to solve the above-described problems and reduce the load on the network related to path control.

The present invention relates to a network system in which a transmission terminal, one or more switches, and a reception terminal are connected to each other via a link, thereby opening a communication path that connects the transmission terminal and the reception terminal. A path control server for storing a topology of the network system including the link, the communication path, and a segment path set in a part of the communication path in a network DB. When a path release instruction for opening the communication path set using the segment path stored in the DB is received, the communication path specified by the path release instruction is satisfied when a predetermined condition is satisfied. by cutting out a portion of the path as the segment path, segment the path setting procedure to be recorded in the network DB Path opening, characterized in that executing the communication path specified by the path release instruction other than the section of the segment path setting the segment path recorded by the procedure, and a procedure for releasing from said network system Method.

  As a result, the number of switches to be controlled can be reduced by using the segment path, and the load on the network can be reduced.

In the present invention, the predetermined condition is that when the control history of the communication path stored in the network DB by the path control server exceeds a predetermined frequency, a segment path in a section exceeding the predetermined frequency is cut out. Features.

  As a result, the segment path can be narrowed down only to the necessary one, so that network resources can be used efficiently.

The present invention relates to a network system in which a transmission terminal, one or more switches, and a reception terminal are connected to each other via a link, thereby opening a communication path that connects the transmission terminal and the reception terminal. A method,
A switch located on a path of the communication path that stores a topology of the network system including the link, the communication path, and a segment path set in a part of the communication path in a network DB; When receiving a path release instruction to release the communication path set using the segment path stored in the network DB, when a predetermined condition is satisfied, the path specified by the path release instruction A part of a communication path is cut out as the segment path and recorded in the network DB, and designated by the path release instruction other than the segment path section recorded by the segment path setting procedure the has been the communication path, and a procedure for releasing from said network system real Characterized in that it.

  As a result, the number of switches to be controlled can be reduced by using the segment path, and the load on the network can be reduced.

The present invention is characterized in that the predetermined condition is when a control history of the communication path stored in the network DB by the switch exceeds a predetermined frequency, and a segment path in a section exceeding the predetermined frequency is cut out. To do.

  As a result, the segment path can be narrowed down only to the necessary one, so that network resources can be used efficiently.

  The present invention is characterized in that a segment path is used for setting and releasing a path. As a result, the number of switches to be controlled can be reduced, and the load on the network can be reduced.

  Hereinafter, an embodiment of a communication system to which the present invention is applied will be described in detail with reference to the drawings. FIG. 1 is an explanatory diagram showing two types of paths defined in the present embodiment. FIG. 1A is a diagram illustrating the segment path SP, and FIG. 1B is a diagram illustrating the communication path CP. FIG. 1 shows an example in which when data is transmitted from the transmission terminal 100 to the reception terminal 500, four switches 300 (switch 301 → switch 302 → switch 303 → switch 304) are sequentially passed.

  First, the communication path CP is a path used when data is transmitted from the transmission terminal 100 to the reception terminal 500. The communication path CP is a path for performing existing communication such as MPLS (Label Switched Path) of MPLS (Multi Protocol Label Switching), such as LDP (Label Distribution Protocol), RSVP (Resource reSerVation Protocol), etc. Established by existing signaling protocols. For example, the transmission terminal 100 establishes a communication path CP (see FIG. 1B) addressed to the reception terminal 500.

  On the other hand, the segment path SP is a concept path uniquely defined in the present embodiment. The segment path SP is a path for performing communication such as an LSP (Label Switched Path) in the same manner as the communication path CP. However, although the segment path SP is set in the network, it is not used for communication alone. Note that these paths (communication path CP, segment path SP) may be paths based on optical communication technology or general communication paths such as ATM (Asynchronous Transfer Mode).

  The segment path SP is a path configured by a partial section of the communication path CP, and a part of the communication path CP is formed with respect to the communication path CP set in the section including the segment path SP. Function as. For example, the segment path SP (see FIG. 1A) between the switches 301 to 304 can be a part of the communication path CP in FIG. The segment path SP may be formed so that the end point thereof does not coincide with the end point of the communication path CP. Such a segment path SP can also be expressed as a path that is not connected to the transmission terminal 100 and the reception terminal 500.

  Therefore, the communication path CP connects the links between the devices, but the segment path SP can be used as a virtual link instead of the link between the devices. That is, the communication path CP is a path obtained by connecting links or segment paths SP between adjacent devices. For example, the communication path CP in FIG. 1B includes the physical link from the transmission terminal 100 to the switch 301, the segment path SP between the switches 301 to 304 (see FIG. 1A), and the switch 301 to the reception terminal 500. The physical links up to are connected in order.

  Hereinafter, two types of communication systems for performing path control according to this embodiment will be described. These two types are different in whether the path control is a centralized type (FIG. 2) or a distributed type (FIG. 3).

  First, in the centralized path control (FIG. 2), an apparatus that collectively performs path control controls all paths on the communication system. Thereby, since the administrator only needs to acquire the operating status of the path from one device, there is an advantage that the path management cost can be reduced.

  FIG. 2 is a configuration diagram illustrating a communication system that performs centralized path control. The communication system includes a path control server 1 that controls a path, a switch 300 that transfers data via a communication path CP, a transmission terminal 100 that includes a transmission-side signal processing unit 120 and a transmission processing unit 110, and reception. A receiving terminal 500 including a side signal processing unit 520 and a reception processing unit 510 is connected by a control network 80 used when communicating a path control signal. That is, the path control server 1 centrally performs path control of each device.

  The transmission terminal 100, the switch 300, and the reception terminal 500 are connected to each other through a signal line 200. The amplifier 400 connects the signal line 200 over a long distance. The signal line 200 is classified as an input line connected to the data transmission terminal 100 or the switch 300 or an output line connected to the data reception terminal 500 or the switch 300.

  First, the transmission terminal 100 is connected to the switch 300 and is connected to the transmission processing unit 110 that transmits data to be transmitted to a line connected via the network and the control network 80, and performs transmission processing in response to reception of the control signal. And a transmission side signal processing unit 120 that activates a path control process set in the unit 110.

  Next, the switch 300 is connected to the control network 80, and the relay-side signal processing unit 310 that activates the path control processing of the switch control unit 312 upon reception of the control signal, and the switch unit 314 according to the path setting instruction. A switch control unit 312 for setting the data and a switch unit 314 for transferring data based on the set path.

  The receiving terminal 500 is connected to the switch 300, receives a transmission signal transmitted through a line connected via the network, and is connected to a reception processing unit 510 that decodes data from the transmission signal and a control network 80. And a reception-side signal processing unit 520 that activates a path control process set in the reception processing unit 510 in response to the reception.

  Further, the path control server 1 includes a path control unit 10 and a network DB 20. Hereinafter, the path control server 1 will be specifically described.

  The path control unit 10 of the path control server 1 creates a path from a specific transmission terminal 100 to the reception terminal 500. Therefore, the path control unit 10 includes a path calculation unit 12, a path setting unit 14, and a DB update unit 16.

  The path calculation unit 12 refers to the information in the topology DB 22 and selects a route that can connect the transmission terminal 100 to the reception terminal 500. In this embodiment, in addition to the link stored in the topology DB 22, the segment path SP stored in the segment path DB 26 is combined to calculate a route candidate connecting the receiving terminal 500 from the transmitting terminal 100. . The path calculation algorithm uses, for example, CSPF (Constrained Shortest Path First). In the route calculation, the cost of the segment path SP may be set lower than that of the normal link so that the segment path SP can be more easily selected as a part of the path than the normal link.

  The path setting unit 14 sets a specific path from the transmission terminal 100 to the reception terminal 500 for the path calculated by the path calculation unit 12. Instruct path setting to all the switches 300 necessary for connecting the transmitting terminal 100 and the receiving terminal 500 via one or a plurality of segment paths SP, and the switch 300 performs connection according to the instructions. Thus, a path between the transmission terminal 100 and the reception terminal 500 is set.

  When the path is set, the DB update unit 16 registers information on the path set by the path setting unit 14 in the set path DB 24, and uses the segment path SP information used for the path connection as a segment. It deletes from the record of path DB26. Also, when the path is released, it is determined whether or not the segment path SP is to be left. If it is determined that the segment path SP is to be left, the switch 300 is not opened and the segment path SP is left and the segment is stored in the DB. Record the path SP information. As a result, the segment path SP can be used when the next path is set.

  The DB update unit 16 may be a method that always leaves the segment path SP as a method for determining whether or not to leave the segment path SP, or the communication path CP setting history information recorded in the path history DB 28. Referring to the method, the path may be left in a section where the communication path CP is set frequently, or the section in which the administrator sets the segment path SP in advance may be used.

  Then, when the DB update unit 16 determines to leave the segment path SP, it may be a section preset by the administrator as a section to be extracted from the communication path CP, or both ends of the communication path CP. A section of the switch 300 adjacent to the terminal corresponding to the point may be used.

  The network DB 20 of the path control server 1 stores information related to a network for which a path is set. Therefore, the network DB 20 includes a topology DB 22 that stores information related to a link connecting each device (switch 300, transmission terminal 100, reception terminal 500) in the network, and information on a communication path CP set in the network. Are set, a segment path DB 26 that records information on the segment path SP set in the network, and a path history DB 28 that records a history relating to control of the communication path CP.

  On the other hand, in the distributed path control (FIG. 3), a device that performs individual path control only needs to control a path that is the route of the device itself. Therefore, since the number of paths handled by each device can be suppressed, there is an advantage that the number of paths that can be set can be increased in the entire communication system.

  FIG. 3 is a configuration diagram illustrating a communication system that performs distributed path control. The difference from FIG. 2 is that the components (path control unit 10 and network DB 20) of the path control server 1 are distributed to each switch 300 instead of being concentrated on one device. As a result, each switch 300 autonomously (independently) controls the path.

  FIG. 4 is a configuration diagram showing the switch unit 314. The switch unit 314 has, for example, four input lines and four output lines, and each input line is connected to each output line via an element EL having two states of passing or connecting. The When the element EL is diagonal, it indicates that it is connected to the output line. In this example, the signal from the input # 1 is output to the output # 3, the signal from the input # 3 is output to the output # 2, and the signals of the input # 2 and the input # 4 are not output to either.

  FIG. 5 is a flowchart showing path control using the segment path SP.

  First, the establishment of the segment path SP (S101) will be described. The switch 301 establishes a segment path SP to the switch 304. Establishment of the segment path SP is realized by instructing connection of each switch 300. The setting of the segment path SP is sequentially transmitted from the upstream side (data transmission side) to the downstream side (data reception side) of the segment path SP, and from the downstream side to the upstream side. This is performed in the device via these messages by the pass reply message. In FIG. 5, a path setting instruction is performed in the order of the switch 301, the switch 302, the switch 303, and the switch 304, and after the path setting is performed, a message (path reply) notifying that the path setting is completed is a path setting. Indicates notification in the reverse direction.

  Next, the establishment of the communication path CP based on the segment path SP (S102) will be described. The transmission terminal 100 sets a communication path CP in the reception terminal 500 via the four switches 300. Here, the path calculation unit 12 sets the communication path CP so as to include the segment path SP established in S101. Then, the path setting unit 14 transmits a control signal so as to set a path to each device that is a route of the communication path CP calculated by the path calculation unit 12. The control signal message (path setting, path reply) is the same as S101.

  When the path setting is instructed, each switch 300 performs the setting, and the input line and the output line are connected. In this state, data transmission from the data transmission to the receiving terminal 500 becomes possible. Each device that has set the communication path CP registers the newly opened communication path CP in the setting path DB 24 and, at the same time, deletes the segment path SP information from the segment path DB 26.

  When the segment path SP exists between the switch 301 and the switch 304, the path control unit 10 completes the path setting by issuing a path setting instruction in the order of the switch 301 and the switches 304 and 500. As a result, the time required for setting the two switches 300 (switch 302, switch 303) in between can be reduced.

  The release of the communication path CP (S103) will be described. The transmission terminal 100 releases the communication path CP established in S102 by, for example, inputting a management command from the administrator. When the path opening is instructed, each switch 300 performs setting, and the connection between the input line and the output line is removed.

  The switch 301 and the switch 304 are opened by removing the connection (input line and output line), and the communication path CP is deleted from the setting path DB 24. At the same time, the fact that there is a segment path SP from the switch 301 to the switch 304 is registered in the segment path DB 26.

  Then, the path control unit 10 determines whether to generate a segment path SP from the communication path CP (leave the segment path SP). At this time, the segment path SP may be generated without fail, or the communication path CP setting and release history may be left in the path history DB 28, and the segment path SP may be left only in a section with a large path setting history.

  The path control operation using the segment path SP has been described above with reference to FIG. In order to explain the effect of the path control using the segment path SP, a comparison is made with the path control not using the segment path SP shown in FIG.

  First, regarding the establishment of the communication path CP (S102 and S201), in the path control (S201) that does not use the segment path SP, the path setting operation of the transmitting terminal 100 to the receiving terminal 500 is 12 round trips. In the path control using the segment path SP (S102), the path setting operation of the transmitting terminal 100 to the receiving terminal 500 is eight times in a round trip.

  Next, regarding the release of the communication path CP (S103 and S202), the path control (S202) that does not use the segment path SP is that the path opening operation of the transmitting terminal 100 to the receiving terminal 500 is 12 round trips. On the other hand, in the path control (S103) using the segment path SP, the path opening operation of the transmitting terminal 100 to the receiving terminal 500 is only 8 times in a round trip.

  As described above, by using the segment path SP, the number of devices that control the communication path CP can be reduced. As a result, it is possible to reduce inefficient path control, such as lengthening the time until path setup is completed with the increase in the number of nodes that are routed, and increase in server load due to an increase in control messages that accompany the increase in the number of paths. Get the effect.

It is explanatory drawing which shows two types of paths regarding one Embodiment of this invention. It is a block diagram which shows the communication system which performs the centralized path | pass control regarding one Embodiment of this invention. 1 is a configuration diagram illustrating a communication system that performs distributed path control according to an embodiment of the present invention. FIG. It is a block diagram which shows the switch part regarding one Embodiment of this invention. It is a flowchart which shows the path control using the segment path | pass regarding one Embodiment of this invention. It is a flowchart which shows the path control which does not use the segment path | pass regarding one Embodiment of this invention.

Explanation of symbols

CP communication path SP segment path 1 path control server 10 path control unit 20 network DB
100 transmitting terminal 300 switch 500 receiving terminal

Claims (4)

A path opening method for releasing a communication path for connecting a transmitting terminal and a receiving terminal in a network system configured by connecting a transmitting terminal, one or more switches, and a receiving terminal with a link. ,
A path control server for storing in the network DB a topology of the network system including the link, the communication path, and a segment path set in a part of the communication path;
When receiving a path opening instruction to open the communication path set using the segment path stored in the network DB ,
When a predetermined condition is satisfied, a segment path setting procedure for cutting out a part of the path of the communication path designated by the path release instruction as the segment path and recording it in the network DB;
A procedure for releasing the communication path designated by the path release instruction other than the segment path section recorded by the segment path setting procedure from the network system;
A path release method characterized by executing: The predetermined condition is when a control history of the communication path stored in the network DB by the path control server exceeds a predetermined frequency, and segment paths in a section exceeding the predetermined frequency are cut out. Item 2. The path opening method according to Item 1. A path opening method for releasing a communication path for connecting a transmitting terminal and a receiving terminal in a network system configured by connecting a transmitting terminal, one or more switches, and a receiving terminal with a link. ,
A switch located on a path of the communication path that stores a topology of the network system including the link, the communication path, and a segment path set in a part of the communication path in a network DB; ,
When receiving a path opening instruction to open the communication path set using the segment path stored in the network DB ,
When a predetermined condition is satisfied, a segment path setting procedure for cutting out a part of the path of the communication path designated by the path release instruction as the segment path and recording it in the network DB;
A procedure for releasing the communication path designated by the path release instruction other than the segment path section recorded by the segment path setting procedure from the network system;
A path release method characterized by executing: 2. The predetermined condition is that when the control history of the communication path stored in the network DB by the switch exceeds a predetermined frequency, a segment path in a section exceeding the predetermined frequency is cut out. The path opening method described in 1.

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