JP2006180358A - Packet transfer apparatus, method thereof and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify and accelerate the processing of searching a packet transfer table to be performed, when changing a transfer path. <P>SOLUTION: In changing a packet transfer path, where which the propriety of path change changes according to the packet transfer state in transfer control units 29 of packet transfer apparatuses 1-4, a packet transfer table 31 is searched and a flag 2 (change propriety information) of a target entry to a change requiring state is initialized; the target entry, in which the flag 2 indicates that change is required is searched from each of entries of the packet transfer table 31, each time at least a predetermined time period has elapsed from the initialization; the propriety of changing the transfer path is confirmed for the searched target entry; and the transfer path of the packet is changed for the target entry, for which the permission of change has been confirmed. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a packet transfer technique, and more particularly, to a transfer path change technique that guarantees the packet arrival order in a packet transfer apparatus on the destination side when a transfer path is dynamically changed by traffic engineering.

Generally, in an IP network, the best effort transfer is performed by the shortest path based routing using a routing protocol such as OSPF (Open Shortest Path First).
According to such shortest path-based routing, reachability can be ensured while suppressing the consumption of network resources. For example, there is a possibility that congestion will occur due to concentration of a large number of user IP flows on a certain path. From the viewpoint of reliability and communication quality, the degree of freedom of path control was low.

As a technique for solving this problem, traffic engineering that dynamically distributes traffic according to the load state in the IP network has been studied. In an IP network that employs such traffic engineering, a transfer route is assigned to communication between subscriber users according to the bandwidth used.
That is, in each packet transfer device, multiple transfer routes are prepared for the same destination, and when the congestion of a specific transfer route is detected, the packet that was going to be transferred to the corresponding route is transferred to the alternative route To do. With this technology, traffic can be distributed to each route, and reliability and communication quality can be improved.

  However, in the above-described technique, since the user flow on the congestion route is mapped to another route without interruption, there is a high possibility that the arrival order of packets will be reversed in the packet transfer apparatus on the arrival side of the changed route.

As a technology to prevent packet arrival order reversal when using such traffic engineering, when the packet forwarding device periodically manages the reference status of each entry in the packet forwarding table and it is necessary to change the forwarding route In addition, a technique for deleting or updating only transfer table entries that have not been referred to for a predetermined period is conceivable.
As a result, the inter-user communication that is continuously transferred is transferred on the old route, and the inter-user communication determined that the arrival order of the packets does not occur can be mapped to the new route.

The applicant has not yet found prior art documents related to the present invention by the time of filing other than the prior art documents specified by the prior art document information described in this specification.
Yuuichi Naruse et, al. "IP-in-IPv6 Overlay Networking Technology for a Terabit-class Super-network", NTT Technical Review, VOL.2, NO.3 Mar. 2004 Kenichi Matsui et, al. "Cut-through Optical Path Control Technology for a Terabit-class Super-network", NTT Technical Review, VOL.2, NO.3 Mar. 2004

In such a conventional technique, whether or not the route can be changed varies depending on the packet transfer status. For a route that cannot be changed, for example, after searching for the entry from the packet transfer table again after a predetermined period, the route is changed. There is a need.
However, there is a possibility that the condition for the route change target and the search key of the forwarding table entry have a one-to-many relationship. Therefore, in order to search for the forwarding table entry subject to the route change control, the route is changed for each search. All entries registered in the packet forwarding table must be inspected using information with a relatively large amount of data such as the destination user address specified as the change condition, resulting in a higher control load than necessary. There was a problem.

  The present invention is intended to solve such a problem, and can simplify and speed up the packet forwarding table search processing performed at the time of forwarding route change, and can reduce the route change control load at the time of traffic engineering. An object of the present invention is to provide a transfer apparatus, method, and program.

  In order to achieve such an object, a packet transfer apparatus according to the present invention is a packet transfer apparatus provided in a communication network, which transfers an input packet to a predetermined transfer path based on its destination address, A storage unit for storing a packet forwarding table having a plurality of pairs of each destination address of a packet, forwarding route information indicating the forwarding route of the packet and change necessity information indicating whether or not the forwarding route is to be changed; The transfer route information corresponding to the destination address of the input packet is acquired from the packet transfer table and the packet is transferred according to the transfer route information, and the transfer route change of each entry of the packet transfer table is changed. A transfer control unit that changes the transfer path of a packet having the destination address for the target entry The transfer control unit includes an initialization unit that searches the packet transfer table and initializes the change necessity information of the target entry to be changed, and each of the packet transfer table at least every predetermined period after the initialization. Change target search means for searching for a target entry whose change necessity information indicates that a change is required from the entry, change possibility check means for checking whether or not the transfer route can be changed for the searched target entry, and target entry for which change has been confirmed And a route changing means for changing the transfer route of the packet having the destination address by updating the transfer route information or deleting the target entry.

  At this time, the changeability confirmation means may determine whether or not the transfer route can be changed based on whether or not the packet of the destination address has not been transferred for a predetermined period.

  Further, the packet transfer table further includes change permission / rejection information indicating whether or not the transfer path can be changed for each entry, and the transfer processing unit changes the entry referred to during packet transfer among the entries in the packet transfer table. The changeability information is set to be unchangeable, and the change target search means sets the changeability information to changeable without changing the transfer path for the entry indicating that the changeability information is unchangeable among the searched target entries. It may be.

At this time, the change target search unit uses at least the time length of the propagation delay time required for the packet having the destination address of the target entry to reach the opposite device via the old route as the switching source as the predetermined period. It may be.
Alternatively, in the change target search means, as a predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having the destination address of the target entry to reach the opposite device via the old route as a switching source Alternatively, the time length of the difference obtained by subtracting the propagation delay time required to reach the opposite device via the network may be used.

  The packet transfer method according to the present invention is a packet transfer method in which an input packet is transferred to a predetermined transfer path based on the destination address by a packet transfer apparatus provided in a communication network, and each packet destination A storage step of storing, in the storage unit, a packet transfer table having a plurality of sets of an address, transfer path information indicating the transfer path of the packet and change necessity information indicating whether or not the transfer path is to be changed, as an entry; Transfer route information corresponding to the destination address of the input packet is obtained from the packet forwarding table and the packet is forwarded according to the forwarding route information, and the forwarding route change target of each entry in the packet forwarding table Change the transfer route of the packet with the destination address for the target entry. A transfer control step, wherein the transfer control step searches the packet transfer table and initializes the change necessity information of the target entry to the change necessity, and every time at least a predetermined period has passed since the initialization. A change target search step for searching for a target entry whose change necessity information indicates that a change is required from each entry in the packet transfer table, a change permission check step for checking whether or not the transfer route can be changed for the searched target entry, A route change step of changing the transfer route of the packet having the destination address by updating the transfer route information of the confirmed target entry or deleting the target entry.

  At this time, in the change possibility confirmation step, whether or not the transfer route can be changed may be determined based on whether or not the packet of the destination address has not been transferred for a predetermined period.

  Further, the packet transfer table further includes change permission information indicating whether or not the transfer route can be changed for each entry. In the transfer processing step, the entry referred to at the time of packet transfer is changed among the entries of the packet transfer table. The changeability information is set to unchangeable, and in the change target search step, the changeability information is set to changeable without changing the transfer route for the entry indicating that the changeability information is unchangeable among the searched target entries. It may be.

At this time, in the change target search step, at least the time length of the propagation delay time required for the packet having the destination address of the target entry to reach the opposite device via the old route as the switching source is used as the predetermined period. May be.
Alternatively, in the change target search step, as a predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having the destination address of the target entry to reach the opposite device via the old route as a switching source Alternatively, the time length of the difference obtained by subtracting the propagation delay time required to reach the opposite device via the network may be used.

  A program according to the present invention is provided in a communication network, and each destination address of a packet and a transfer path of the packet are transferred to a computer of a packet transfer apparatus that transfers an input packet to a predetermined transfer path based on the destination address. A storage step of storing in the storage unit a packet forwarding table having a plurality of pairs of forwarding route information indicating the destination and whether or not the forwarding route is to be changed as an entry, and a destination address of the input packet The transfer processing step for acquiring the transfer route information corresponding to the packet from the packet transfer table and transferring the packet according to the transfer route information, and the destination for the target entry whose transfer route is to be changed among the entries of the packet transfer table Transfer control step for changing the transfer path of a packet having an address The transfer control step searches the packet transfer table and initializes the change necessity information of the target entry to be changed, and sets the packet transfer table in the packet transfer table every time at least a predetermined period has passed since the initialization. A change target search step for searching for a target entry whose change necessity information indicates that a change is required from each entry, a change permission check step for checking whether or not the transfer route can be changed for the searched target entry, and a target for which change has been confirmed A route change step of changing the transfer route of the packet having the destination address by updating the transfer route information of the entry or deleting the target entry.

  At this time, in the change possibility confirmation step, whether or not the transfer route can be changed may be determined based on whether or not the packet of the destination address has not been transferred for a predetermined period.

  Furthermore, in the forwarding process step, changeability information indicating whether or not the forwarding route can be changed is set to unchangeable for the entry referenced during packet forwarding among the entries in the packet forwarding table. Of the target entries, the change permission information may be set to changeable without changing the transfer path for the entry whose change permission information indicates that change is not possible.

Further, in the change target search step, at least the length of the propagation delay time required for the packet having the destination address of the target entry to reach the opposite device via the old route as the switching source is used as the predetermined period. May be.
Alternatively, in the change target search step, as a predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having the destination address of the target entry to reach the opposite device via the old route as a switching source Alternatively, the time length of the difference obtained by subtracting the propagation delay time required to reach the opposite device via the network may be used.

  According to the present invention, when changing a packet transfer route in which the possibility of route change changes according to the packet transfer status, the packet transfer table is searched and the change necessity information of the target entry is initialized to need to be changed. Each time the period or more elapses, the target entry whose change necessity information indicates that the change is necessary is searched from each entry of the packet forwarding table, and whether or not the transfer route can be changed for the searched target entry is confirmed. Since the packet transfer route is changed for the target entry, the target entry can be searched only by checking the change necessity information indicating whether or not the change is necessary in the packet transfer table search process required when changing the transfer route. .

Therefore, when searching for a target entry subject to route change from the packet forwarding table, all of the information registered in the packet forwarding table using relatively large amount of information such as the destination user address specified as the route changing condition is used. It is not necessary to check the match for each entry for a predetermined period, and the packet forwarding table search process can be simplified and speeded up.
As a result, when route change control is performed by the packet transfer apparatus based on traffic engineering or the like, it is possible to reduce the load required for the route management processing, and to realize speeding up of the route change control.

Next, embodiments of the present invention will be described with reference to the drawings.
[Communication network]
First, a network model example of a communication network provided with a packet transfer apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing an example of a network model of a communication network in which a packet transfer apparatus according to an embodiment of the present invention is installed.

This communication network is composed of packet transfer apparatuses 1 to 4, frame transfer apparatuses 5 and 6, and optical path switches 7 and 8. Each terminal 9 to 24 is connected to each other via a user network 1A to 4A. 1 to 4. These packet transfer apparatuses 1 to 4 are connected by frame transfer apparatuses 5 and 6 and optical path switches 7 and 8.
The address of user # 1 is assigned to the terminal 9, the address of user # 2 is assigned to the terminal 10, the address of user # 3 is assigned to the terminal 11, and the user is assigned to the terminal 12 An address of # 4 is assigned, an address of user # 5 is assigned to the terminal 13, and an address of user # 6 is assigned to the terminal.

  The terminal 15 is assigned an address of user # 7, the terminal 16 is assigned an address of user # 8, the terminal 17 is assigned an address of user # 9, and the terminal 18 Is assigned user # 10, terminal 19 is assigned user # 11, terminal 20 is assigned user # 12, and terminal 21 is user # 13. An address is assigned, the terminal 22 is assigned an address of user # 14, the terminal 23 is assigned an address of user # 15, and the terminal 24 is assigned an address of user # 16. Yes.

The packet transfer apparatuses 1 to 4, the frame transfer apparatuses 5 and 6, and the packet transfer apparatuses 1 to 4 are connected by an optical path (not shown) such as an optical wavelength. The optical path switches 7 and 8 have a function of switching the optical path and changing the connection relationship between the devices.
The frame transfer apparatuses 5 and 6 perform a relay process for packets transferred between the packet transfer apparatuses 1 to 4.
Packets between terminals are transferred from the sending terminal to the originating packet transfer device, then forwarded to the destination packet forwarding device via the frame forwarding device, and forwarded to the destination terminal. After being transferred from the terminal to the originating packet transfer device, the packet may be transferred to the destination packet transfer device without passing through the frame transfer device, and may be transferred to the destination terminal.

A backbone network composed of packet transfer apparatuses 1 to 4, frame transfer apparatuses 5 and 6, and optical path switches 7 and 8 is a core network 25, and a network composed of terminals is the Internet 26.
The transfer that does not go through the frame transfer devices 5 and 6 is called cut-through optical path transfer, and is installed between packet transfer devices with a high traffic demand. In addition, it is possible to control the connection relationship between devices of the optical path switch as the traffic demand changes, and to change the packet transfer devices that perform cut-through optical path transfer together with the traffic demand.

FIG. 2 is an example of a physical model and a logical model of a communication network in which the packet transfer apparatus of the present invention is installed.
The packet transfer apparatuses 1 to 4 are connected by a plurality of transfer paths. These transfer paths include physical transfer paths established by optical paths (optical wavelengths, optical fibers), IP paths in IP networks, and LSP (Label Switch Path) in MPLS (Multi Protocol Label Switching) networks. There is a logical transfer path.
In the present embodiment, the optical path indicates a physical transfer path, and the LSP indicates a logical transfer path.

  For example, from the packet transfer apparatus 1 to the packet transfer apparatus 3, a logical transfer path LSP 110 established using a physical transfer path including the optical path 101, the frame transfer apparatus 5, and the wavelength path 103, and the optical path 105 , Frame transfer device 6, logical transfer path LSP 113 established using a physical transfer path consisting of wavelength path 107, and logical transfer established using a physical transfer path consisting of optical path 107 They are connected by a route LSP116. Each logical transfer path is given a path identifier for identifying the path.

A logical transfer path is set up between all packet transfer apparatuses. In this embodiment, since the LSP of the MPLS network is adopted, the logical transfer paths LSP110 to 135 are installed in a full mesh between the packet transfer apparatuses.
In this embodiment, one optical path occupies one physical link. However, for example, when a technique such as WDM (Wavelength Division Multiplexing) is adopted, a plurality of optical paths are converted into one physical link. Can be accommodated.

FIG. 3 is an example of a transfer path between the packet transfer apparatus and the packet transfer apparatus in the network of FIG. 2 in which the packet transfer apparatus of the present invention is installed.
In the present embodiment, the LSP 110 established on the optical path 101, the frame transfer apparatus 5, and the optical path 103, the LSP 113 established on the optical path 105, the frame transfer apparatus 6, and the optical path 107, and established on the optical path 109. LSP 116 is present.
In the core network, a packet is encapsulated by a shim header describing an LSP number, and is transferred according to the LSP number.

  The packet transfer apparatus 1 and the terminal 9 are connected via a link 127, the packet transfer apparatus 1 and the terminal 10 are connected via a link 128, and the packet transfer apparatus 1 and the terminal 11 are linked 129. The packet transfer apparatus 1 and the terminal 12 are connected via a link 130, the packet transfer apparatus 1 and the terminal 17 are connected via a link 131, and the packet transfer apparatus 1 and the terminal 18 are connected via a link 132, the packet transfer apparatus 1 and the terminal 19 are connected via a link 133, and the packet transfer apparatus 1 and the terminal 20 are connected via a link 134. Has been.

[Packet transfer equipment]
Next, with reference to FIG. 4, a packet transfer apparatus according to an embodiment of the present invention will be described. FIG. 4 is a block diagram showing the configuration of the packet transfer apparatus according to the embodiment of the present invention. Here, the packet transfer apparatus 1 will be described as an example, but the other packet transfer apparatuses 2 to 4 have the same configuration.

  The packet transfer apparatus 1 includes an input interface unit 27, a transfer processing unit 28, a transfer control unit 29, and an output interface unit 30. Each of these units executes various kinds of information such as an arithmetic processing unit (not shown) that realizes a functional unit by causing the CPU and hardware to cooperate with each other by executing a program, and the above-described program and a packet transfer table 31 described later. Is composed of a storage device (not shown) such as a hard disk or a memory for storing data, and a communication interface unit (not shown) for transmitting and receiving various packets via a network.

  When the header area of the received frame is an MPLS shim header, the input interface unit 27 determines that the frame is a core frame, removes the shim header, decapsulates the user packet, and extracts the user packet. It has a function of transferring to the transfer processing unit 28 and a function of determining that the frame is a user packet when the header area of the received frame is a user address and transferring it to the transfer processing unit 28.

The transfer processing unit 28 has a packet transfer table 31.
The packet transfer table 31 includes, from the destination user address of the received user packet, an LSP number indicating the output destination LSP, a flag 1 (changeability information) indicating whether the transfer path for transferring the destination user address can be switched, and the destination It has a function of deriving a flag 2 (change necessity information) indicating whether or not the transfer path for transferring the user address is necessary.
The transfer processing unit 28 searches the packet transfer table 31 using the destination user address of the user packet received from the input interface unit 27 as a key, derives the output destination LSP number of the user packet, and transfers the user packet each time. In addition, the flag 1 of the entry that has been hit in the packet transfer table 31 is set and cannot be changed.

FIG. 5 is a configuration example of a packet transfer table used in the packet transfer apparatus according to the present embodiment.
In the packet transfer table 31, each entry is not subject to route change in normal times, and all the flags 2 are all in a reset state (not subject to change), and the flag 2 is set only during route change control and is subject to change. Exists. In the present embodiment, entry update requests are generated at the destination user addresses # 9 and # 10.

The transfer control unit 29 has a changed path management table 32 and a timer 33.
FIG. 6 shows an example of the configuration of the changed route management table used in the packet transfer apparatus according to this embodiment. The changed route management table 32 has a function of holding, as instruction information, the destination user address and the changed LSP number described in the route change notification of the output destination LSP related to a certain destination user address received from the outside, for example. ing.
The timer 33 has a function of increasing the timer value every predetermined period. In the present embodiment, for example, the timer value is incremented by 1 every 1 millisecond.

  For the route change notification of the output destination LSP related to a certain destination user address, the transfer control unit 29 adds the destination user address and LSP number pair of the route change notification to the changed route management table 32 and the destination user address. A function that searches the packet transfer table 31 of the transfer processing unit 28 as a search key, resets the flag 1 of the hit entry and sets the flag 2 (initialization means), and the timer value of the timer 33 is predetermined. When the value reaches the value, it has a function of searching for a target entry in which the flag 2 is set in the packet transfer table 31 of the transfer processing unit 28 (change target search means).

  Furthermore, the transfer control unit 29 checks whether the flag 1 of the hit target entry is in a reset state and confirms whether or not the route of the entry can be changed (change change checking means). A function (route changing means) that rewrites the described LSP number to an LSP number stored in the changed route management table 32 and deletes information related to the destination user address and LSP number from the changed route management table 32; And a function to initialize a timer value.

The initialization of the timer value is executed once after the processing is started in response to the route change notification, the flag 1 is first reset and the flag 2 is set.
Thereafter, the route change process is performed after a predetermined period according to the specified value of the timer 33 has elapsed, and the timer value is initialized each time the process for each target entry is completed. As this specified value, a value that specifies a sufficient time during which the packet arrival order is guaranteed even if the route is changed between routes having different packet transfer delay times may be used.

The output interface unit 30 has an output link identification table 34.
FIG. 7 is a configuration example of an output link identification table used in the packet transfer apparatus according to this embodiment. The output link specification table 34 has a function of specifying an output link from the header information.
The output interface unit 30 searches the output link specification table 34 using the destination address of the packet received from the transfer processing unit 28 as a key, transmits the corresponding frame to the output link, and is described in the shim header of the received frame. The output link specifying table 34 is searched using the LSP number as a key, and the corresponding frame is transmitted to the output link.

  As described above, in the present embodiment, when the packet transfer apparatus 1 to 4 changes the packet transfer path whose path changeability changes according to the packet transfer status, the packet transfer table 31 is searched to search for the target entry. The flag 2 (change necessary / unnecessary information) is initialized to change necessary, and at least every time a predetermined period or more elapses, a target entry indicating that the flag 2 needs to be changed is searched from each entry of the packet forwarding table 31. Since whether or not the transfer route can be changed is confirmed and the packet transfer route is changed for the target entry for which the change is confirmed, a change is required in the search processing of the packet transfer table 31 necessary for changing the transfer route. The target entry can be searched simply by checking the flag 2 indicating NO.

Therefore, when searching for a target entry subject to route change from the packet forwarding table, all of the information registered in the packet forwarding table using relatively large amount of information such as the destination user address specified as the route changing condition is used. It is not necessary to check the match for each entry for a predetermined period, and the packet forwarding table search process can be simplified and speeded up.
As a result, when route change control is performed by the packet transfer apparatus based on traffic engineering or the like, it is possible to reduce the load required for the route management processing, and to realize speeding up of the route change control.

[Packet transfer operation]
Next, with reference to FIG. 3 and FIG. 8, a packet transfer operation will be described as an operation of the packet transfer apparatus according to the present embodiment. FIG. 8 is an explanatory diagram showing a packet transfer operation of the packet transfer apparatus according to this embodiment.

First, assuming that communication is started between the terminal 9 of the user # 1 and the terminal 17 of the user # 9, a packet transmitted from the terminal 9 to the terminal 17 is defined as a user packet 201.
The packet transfer apparatus 1 receives the user packet 201 from the link 127 by the input interface unit 27. The input interface unit 27 determines that the received packet is a user packet and transfers the packet to the transfer processing unit 28.

When the transfer processing unit 28 receives the user packet 201 from the input interface unit 27, the transfer processing unit 28 refers to the packet transfer table 31 using the user # 9 that is the destination user address as a search key, and identifies the output destination transfer path The entry 35 in which the LSP 110 is described is detected, the flag 1 (changeability information) of the entry 35 is checked, and since the reset state “0” indicating change is set, this is set state “1” indicating that change is not possible. To "".
Also, from the information described in the entry 35, a shim header in which transfer information of the LSP 110 is described is added to the user packet 201 to generate the core frame 202. Then, the transfer processing unit 28 transmits the core frame 202 to the output interface unit 30.

  The output interface unit 30 specifies the optical path 101 by referring to the output link specifying table 34 using the LSP 110 that is shim header information of the core frame 202 as a search key, and outputs the core frame 202 to the optical path 101.

Subsequently, it is assumed that communication is started between the terminal 9 of the user # 1 and the terminal 10 of the user # 2, and a packet transmitted from the terminal 9 to the terminal 10 is defined as a user packet 203.
The packet transfer apparatus 1 receives the user packet 203 from the link 127 by the input interface unit 27. The input interface unit 27 determines that the received packet is a user packet and transfers the packet to the transfer processing unit 28.

When the transfer processing unit 28 receives the user packet 203 from the input interface unit 27, the transfer processing unit 28 refers to the packet transfer table 31 by using the user # 2 that is the destination user address as a search key. At this time, since there is no description of the LSP number in the detected entry, it is determined that the packet is addressed to the user accommodated by the packet transfer apparatus 1 itself, and the user packet 203 is transmitted to the output interface unit 30 as it is.
The output interface unit 30 refers to the output link specifying table 34 using the user # 2 that is the destination address of the user packet 203 as a search key, specifies the output link 128, and outputs the user packet 203 to the link 128.

Finally, assuming that communication has started between the terminal 17 and the terminal 9, a packet transmitted from the terminal 17 to the terminal 9 is referred to as a user packet 204.
The user packet 204 is given a shim header in the packet transfer apparatus 3 and is transmitted to the packet transfer apparatus 1 as a core frame 205.
The packet transfer apparatus 1 receives the core frame 205 from the optical path 101 by the input interface unit 27. The input interface unit 27 determines that the received packet is a core frame, extracts the user packet 204 by removing the shim header of the core frame 205, and transfers the user packet 204 to the transfer processing unit 28.

When the transfer processing unit 28 receives the user packet 204 from the input interface unit 27, the transfer processing unit 28 refers to the packet transfer table 31 using the user # 1 that is the destination user address as a search key.
At this time, since the LSP number is not described in the detected entry, it is determined that the packet is addressed to the user accommodated by the packet transfer apparatus 1 itself, and the user packet 204 is transmitted to the output interface unit 30 as it is.
The output interface unit 30 refers to the output link specifying table 34 using the user # 1 that is the destination address of the user packet 204 as a search key, specifies the output link 127, and outputs the user packet 204 to the link 127.

[Route change operation]
Next, with reference to FIG. 9 and FIG. 10, a route change operation will be described as the operation of the packet transfer apparatus according to the present embodiment. FIG. 9 is an explanatory diagram showing the path changing operation of the packet transfer apparatus according to this embodiment. FIG. 10 is a flowchart showing route change processing of the packet transfer apparatus according to the present embodiment.
In the packet transfer operation of the packet transfer apparatus described above, the transfer path indicated by LSP 110 is used for communication between the terminal 9 and the terminal 17 in FIG. Here, as shown in FIG. 9, an example will be described in which the communication transfer path is changed to the transfer path indicated by the LSP 116 based on a predetermined path change notification.

  The transfer control unit 29 of the packet transfer apparatus 1 starts the route change process of FIG. 10 in response to the route change notification. First, instruction information for changing the LSP number of the forwarding table entry whose destination user address is detected by the user # 9 included in the route change notification and the forwarding table entry whose destination user address is detected by the user # 10. The instruction information for changing the LSP number to the LSP 116 is an entry that leads the LSP 116 using the destination user address “user # 9” as a search key and an entry that leads the LSP 116 using the destination user address “user # 10” as a search key. Save in table 32.

  At the same time, the packet transfer table 31 is searched using the destination user address “user # 9” as a search key (step 300), and the flag 1 (changeable information) of the hit entry 38 is reset to “0” (changeable). ) And flag 2 (change necessary / unnecessary information) is set to “1” (change required) (step 301: initialization means), and packet transfer is performed using the destination user address “user # 10” as a search key. The table 31 is searched (step 300), the flag 1 (changeability information) of the hit entry 39 is set to the reset state “0” (changeable), and the flag 2 (change necessity information) is set to the set state “1”. "(Requires change)" (step 301: initialization means).

  Subsequently, the transfer control unit 29 initializes the timer 33 and starts measuring time (step 310). In the present embodiment, the timer 33 measures 100 milliseconds as a predetermined period based on the specified value, and is reset every 100 milliseconds (step 311).

  As this predetermined period, the packet of the destination address of the target entry subject to route change reaches at least the opposite device such as the packet forwarding device serving as the forwarding destination via the old route serving as the switching source from the packet forwarding device. If a time length equal to or longer than the required propagation delay time is used, the route change operation is performed at the timing when all the packets transferred in the past have reached the opposite device, and a safer route change operation can be realized.

  Alternatively, as a predetermined period, from the propagation delay time required for the packet of the destination address of the target entry to be route-changed to reach the opposite device via the old route that is the switching source, the packet is sent via the new route that is the switching destination. If a time length greater than the difference obtained by subtracting the propagation delay time required to reach the opposite device is used, packets transferred in the past through the old route and packets started to transfer through the new route The route change operation is performed at a timing at which the arrival order at the opposite device does not change (does not pass), and a safer route change operation can be realized.

  In this way, the transfer control unit 29 performs the path change control at least after a predetermined period has elapsed since the initialization of the flag in step 301. The interval for performing the route change control may be at least a predetermined period or more, that is, a period in which the packet arrival order is guaranteed, and does not need to be performed at a constant cycle. For example, an RTT (Round Trip Time) between the opposite packet transfer devices by periodically transmitting / receiving ICMP (Internet Control Message Protocol) ping (Packet InterNet Groper) packets to / from the opposite packet transfer device for a predetermined period. : Round-trip transfer delay time) may be calculated and dynamically changed according to the variation of the RTT.

When the timer 33 reaches the specified value (step 311: YES), the transfer control unit 29 searches the packet transfer table 31 of the transfer processing unit 28 for an entry in which the flag 2 is set (need to be changed) (step 312). : Change target search means).
When the entry 38 is hit as a target entry in this search (step 313: YES), the flag 1 of the searched entry 38 is checked (step 314: change permission confirmation means).

Here, in a predetermined period from the initialization of the timer 33 in step 310 to the timer 33 reaching the specified value in step 311, the entry 38 is not referred to and there is no packet transfer on the route, and the route change is safe. If it is possible to do so, the flag 1 of the entry 38 remains in the reset state (changeable).
Thus, when the flag 1 of the entry 38 is in the reset state (step 314: YES), the entry 38 is updated based on the information described in the changed route management table 32 (step 315: route changing means). . Here, the LSP number is updated from LSP110 to LSP116. At this time, the entry 36 in the change path management table 32 corresponding to the updated instruction information is deleted, and the flag 2 is set to the reset state “0” (not to be changed).

Then, the transfer control unit 29 resumes searching for an entry in which the flag 2 is set (change required) from the entry described after the entry 38 in the packet transfer table 31 of the transfer processing unit 28 (step 317).
If the entry 39 is hit as a target entry in this search (step 318: YES), the process returns to step 314 to check the flag 1 of the searched entry 39 (step 314).

Here, during the period from the initialization of the timer 33 in step 310 to the time when the timer 33 reaches the specified value in step 311, the entry 39 is referred to and the packet is transferred along the route, so that the route can be changed safely. If not, flag 1 of entry 39 is set (cannot be changed).
As described above, when the flag 1 of the entry 39 is in the set state (step 314: NO), in order to reconfirm whether or not the route change can be safely performed in the period until the timer 33 reaches the specified value, The flag 1 is set to a reset state “0” (changeable) (step 316: change target search means).
As a result, in contrast to the packet transfer table 37 immediately before the route change, the packet transfer table immediately after the change becomes the packet transfer table 40, and the entries 38 and 39 are updated to the entries 41 and 42, respectively.

Thereafter, the transfer control unit 29 resumes the search for the entry in which the flag 2 is set (change required) from the entry described after the entry 39 in the packet transfer table 31 of the transfer processing unit 28 (step 317). . If the target entry is not hit in this search (step 318: NO), the process returns to step 310 to initialize the timer 33, and the above-described steps 312 to 318 are periodically repeated every time the timer reaches a specified value. Execute.
In step 313, when there is no entry in which the flag 2 is set (change required) (step 313: NO), the series of route change processing is terminated. At this time, there should be no entry in the change path management table 32.

  As described above, in the present embodiment, when the packet transfer apparatus 1 to 4 changes the packet transfer path whose path changeability changes according to the packet transfer status, the packet transfer table 31 is searched to search for the target entry. The flag 2 (change necessary / unnecessary information) is initialized to change necessary, and at least every time a predetermined period or more elapses, a target entry indicating that the flag 2 needs to be changed is searched from each entry of the packet forwarding table 31. Since whether or not the transfer route can be changed is confirmed and the packet transfer route is changed for the target entry for which the change is confirmed, a change is required in the search processing of the packet transfer table 31 necessary for changing the transfer route. The target entry can be searched simply by checking the flag 2 indicating NO.

Therefore, when searching for a target entry subject to route change from the packet forwarding table, all of the information registered in the packet forwarding table using relatively large amount of information such as the destination user address specified as the route changing condition is used. It is not necessary to check the match for each entry for a predetermined period, and the packet forwarding table search process can be simplified and speeded up.
As a result, when route change control is performed by the packet transfer apparatus based on traffic engineering or the like, it is possible to reduce the load required for the route management processing, and to realize speeding up of the route change control.

Also, when determining whether or not a route can be changed, the packet arrival order is guaranteed even if the route is changed between a flag 1 (change enable / disable information) set for each packet transfer and a route having a different packet transfer delay time. By using the timer 33 that measures time, it is possible to reliably determine whether or not the route can be changed with extremely simple processing and configuration.
In the above description, the case where it is determined using the flag 1 and the timer 33 whether or not the route change can be executed safely has been described as an example. However, the present invention is not limited to this, and other route update availability determination is possible. Means may be used, and the same effects as described above can be obtained.

It is a block diagram which shows the network model example of the communication network which installed the packet transmission apparatus concerning one embodiment of this invention. It is an example of the physical model and logical model of the communication network which installed the packet transfer apparatus of this invention. It is an example of the transfer path | route between a packet transfer apparatus and a packet transfer apparatus in the network of FIG. 2 which installed the packet transfer apparatus of this invention. It is a block diagram which shows the structure of the packet transfer apparatus concerning one embodiment of this invention. It is a structural example of the packet transfer table used with the packet transfer apparatus concerning this Embodiment. It is an example of a structure of the change path | route management table used with the packet transfer apparatus concerning this Embodiment. It is an example of a structure of the output link specific table used with the packet transfer apparatus concerning this Embodiment. It is explanatory drawing which shows the packet transfer operation | movement of the packet transfer apparatus concerning this Embodiment. It is explanatory drawing which shows the path | route change operation | movement of the packet transfer apparatus concerning this Embodiment. It is a flowchart which shows the route change process of the packet transfer apparatus concerning this Embodiment.

Explanation of symbols

1, 2, 3, 4 ... Packet transfer device, 1A-4A ... User network, 5, 6 ... Frame transfer device, 7, 8 ... Optical path switch, 9-24 ... Terminal, 25 ... Core network, 26 ... Internet, 27 ... Input interface unit, 28 ... Transfer processing unit, 29 ... Transfer control unit, 30 ... Output interface unit, 31 ... Packet transfer table, 32 ... Change path management table, 33 ... Timer, 34 ... Output link specification table, 35, 36, 38, 39, 41, 42 ... entry, 37 ... packet transfer table (immediately before route change), 40 ... packet transfer table (immediately after route change), 101-109 ... optical path, 110-135 ... LSP, 201, 203 204, user packets, 202, 205, core frames.

Claims (15)

A packet transfer device that is provided in a communication network and transfers an input packet to a predetermined transfer path based on its destination address,
A storage unit for storing a packet forwarding table having a plurality of pairs of each destination address of a packet, forwarding route information indicating the forwarding route of the packet and change necessity information indicating whether or not the forwarding route is to be changed; ,
A transfer processing unit that acquires transfer path information corresponding to the destination address of the input packet from the packet transfer table and transfers the packet according to the transfer path information;
A transfer control unit that changes a transfer path of a packet having the destination address with respect to a target entry that is a target of a transfer path change among the entries of the packet transfer table, and
The transfer control unit searches from the packet transfer table and initializes the change necessity information of the target entry to change required, and from each entry of the packet transfer table at least every predetermined period or more About change target search means for searching for a target entry whose change necessity information indicates that it needs to be changed, change possibility check means for checking whether or not a transfer route can be changed for the searched target entry, and target entry for which change has been confirmed A packet transfer apparatus comprising: a route change unit that changes a transfer route of a packet having the destination address by updating the transfer route information or deleting the target entry. The packet transfer apparatus according to claim 1, wherein
The packet transfer apparatus according to claim 1, wherein the change enable / disable confirmation unit determines whether or not the transfer route can be changed based on whether or not the packet of the destination address is not transferred over the predetermined period. The packet transfer apparatus according to claim 2, wherein
The packet forwarding table further includes changeability information indicating whether or not the transfer route can be changed for each entry,
The transfer processing unit sets the changeability information for the entry referred to during packet transfer among the entries of the packet transfer table to be unchangeable,
The packet transfer apparatus according to claim 1, wherein the change target search unit sets the change permission information to changeable without changing the transfer path for the entry whose change permission information indicates that change is not possible among the searched target entries. The packet transfer apparatus according to claim 1, wherein
The change target search means uses, as the predetermined period, at least a time length of a propagation delay time required for a packet having a destination address of the target entry to reach the opposite device via an old route as a switching source. A characteristic packet transfer apparatus. The packet transfer apparatus according to claim 1, wherein
The change target search means, as the predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having a destination address of the target entry to reach the opposite device via an old route as a switching source A packet transfer device using a time length of a difference obtained by subtracting a propagation delay time required to reach the opposite device via A packet transfer method for transferring an input packet to a predetermined transfer path based on a destination address by a packet transfer device provided in a communication network,
A storage unit stores a packet transfer table having a plurality of combinations of each destination address of a packet, transfer route information indicating the transfer route of the packet, and change necessity information indicating whether or not the transfer route is to be changed as an entry. A memory step;
A transfer processing step of acquiring transfer path information corresponding to the destination address of the input packet from the packet transfer table and transferring the packet according to the transfer path information;
A transfer control step of changing a transfer path of a packet having the destination address for a target entry that is a target of a transfer path change among the entries of the packet transfer table, and
The transfer control step includes an initialization step of searching the packet transfer table and initializing the change necessity information of the target entry to be changed, and each entry of the packet transfer table at least every predetermined period of time. A change target search step for searching for a target entry whose change necessity information indicates that a change is required, a change permission check step for checking whether a transfer path can be changed for the searched target entry, and a target entry for which change is confirmed And a route change step for changing the transfer route of the packet having the destination address by updating the transfer route information or deleting the target entry. The packet transfer method according to claim 6, wherein
The packet transfer method characterized in that the change permission confirmation step judges whether or not the transfer route can be changed based on whether or not the packet of the destination address has not been transferred over the predetermined period. The packet transfer method according to claim 7,
The packet forwarding table further includes changeability information indicating whether or not the transfer route can be changed for each entry,
The transfer processing step sets the changeability information for the entry referenced at the time of packet transfer among the entries of the packet transfer table to be unchangeable,
In the packet transfer method, the change target search step sets the change enable / disable information to changeable without changing the transfer path for an entry whose change enable / disable information indicates that change is not possible among the searched target entries. The packet transfer method according to claim 6, wherein
The change target search step uses, as the predetermined period, at least a time length of a propagation delay time required for a packet having the destination address of the target entry to reach the opposite device via the old route as a switching source. A characteristic packet transfer method. The packet transfer method according to claim 6, wherein
The change target search step includes, as the predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having a destination address of the target entry to reach the opposite device via an old route as a switching source. A packet transfer method using a time length of a difference obtained by subtracting a propagation delay time required to reach the opposite device via To a computer of a packet transfer device that is provided in a communication network and transfers an input packet to a predetermined transfer path based on its destination address,
A storage unit stores a packet transfer table having a plurality of combinations of each destination address of a packet, transfer route information indicating the transfer route of the packet, and change necessity information indicating whether or not the transfer route is to be changed as an entry. A memory step;
A transfer processing step of acquiring transfer path information corresponding to the destination address of the input packet from the packet transfer table and transferring the packet according to the transfer path information;
A transfer control step of changing a transfer path of a packet having the destination address for a target entry that is a target of a transfer path change among the entries of the packet transfer table; and
The transfer control step includes an initialization step of searching the packet transfer table and initializing the change necessity information of the target entry to be changed, and each entry of the packet transfer table at least every predetermined period of time. A change target search step for searching for a target entry whose change necessity information indicates that a change is required, a change permission check step for checking whether a transfer path can be changed for the searched target entry, and a target entry for which change is confirmed And a route change step for changing a transfer route of a packet having the destination address by updating the transfer route information or deleting the target entry. The program according to claim 11.
The program for determining whether or not the transfer route can be changed based on whether or not the packet of the destination address has not been transferred for the predetermined period. The program according to claim 12,
The transfer processing step sets change enable / disable information indicating whether or not the transfer route can be changed to an unchangeable entry that is referred to during packet transfer among the entries of the packet transfer table.
The change target search step sets the change enable / disable information to changeable without changing the transfer path for the entry indicating that the change enable / disable information is not changeable among the searched target entries. The program according to claim 11.
The change target search step uses, as the predetermined period, at least a time length of a propagation delay time required for a packet having the destination address of the target entry to reach the opposite device via the old route as a switching source. A special program. The program according to claim 11.
The change target search step includes, as the predetermined period, at least a new route as a switching destination from a propagation delay time required for a packet having a destination address of the target entry to reach the opposite device via an old route as a switching source. A program characterized by using a time length of a difference obtained by subtracting a propagation delay time required to reach the opposite device through the network.

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