JP2005159983A - Label switching network, root server, and label edge router - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a label switching network or the like capable of reducing a table capacity required for a label edge router without reducing the transfer capability of an entire network. <P>SOLUTION: A root server 10 particularizes a cut-through path label denoting a cut-through path for transferring a user packet not via the root server 10 from a sender side label edge router 11 to a receiver side label edge router 13 on the basis of the received label-attached user packet and informs the sender label edge router 11 about cut-through data including the cut-through path label and a destination address of the user packet. The sender label edge router 11 sets the cut-through path from the sender label edge router 11 up to the receiver side label edge router 13 on the basis of the cut-through path label and the destination address included in the received cut-through data. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a connection type network technology, and more particularly to a label switching network technology used when constructing a large-scale packet communication network.

  In a large-scale packet communication network such as the Internet, a label switching network technique which is one of connection type network techniques is used in order to speed up packet transfer between routers.

  For example, MPLS (Multi Protocol Label Switching) technology, which is one of the label switching network technologies, transmits a packet by adding data link layer connection information called a label to a packet with an MPLS-compatible router and refers to only the label. This is a technology for transferring to an output port. A general router used in an IP network examines a destination IP address stored in header information of a received packet and determines an appropriate output port. A label corresponding to a connection set in advance in the data link layer By using this, such processing can be omitted, and high-speed packet transfer is realized.

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.
Junichi MURAYAMA et, al. “Traffic-Driven Optical IP Networking Architecture”, IEICE TRANS. COMMUN., VOL.E86-B, NO.8 AUGUST 2003 Takahiro Tsujimoto, Jun Yagi, Junichi Murayama, Kazuhiro Matsuda, Hiroyuki Ishii, “Evaluation of optical cut-through method in TSN”, The Institute of Electronics, Information and Communication Engineers, 2003 IEICE General Conference, B-7-82 (2003) March)

  However, in such a conventional technique, a packet transfer route is set between all the label edge routers that accommodate the user network, and thus a large-capacity storage means is required for managing these packet transfer routes. As a result, there is a problem that a small label edge router with a small storage capacity cannot be connected to a large packet network, and that the label edge router becomes large and costs increase.

For example, in a conventional label switching network using MPLS technology, that is, an MPLS network, a packet transfer path called LSP (Label Switched Path) is set in a mesh form between label edge routers. Also, based on this, it is necessary to set the transfer route so that the label edge router as the exit can be specified for every destination subnet.
For this reason, even if the label edge router is small, when the entire scale of the IP network is large, it is necessary to set many transfer routes, and the transfer capacity is very small. However, a large-capacity table is required as a table for managing the transfer path.

In addition, in order to solve this problem, a network configuration in which a specific label edge router is positioned as a dedicated relay, the label edge router is used as a hub, and the label edge routers accommodating user terminals are connected in a hub-and-spoke manner. Can be considered. According to this network configuration, it is only necessary to set one default transfer path toward the label edge router dedicated to relay in each label edge router that accommodates user terminals. There is a problem that the transfer performance of the entire network is lowered due to the concentration on the edge router.
The present invention has been made to solve such problems, and provides a label switching network, a route server, and a label edge router that can reduce the table capacity required for the label edge router without reducing the transfer capability of the entire network. It is intended to provide.

  In order to achieve such an object, the label switching network according to the present invention adds a label for specifying a transfer route to a user packet addressed to a desired terminal transmitted from a terminal of a user network to be accommodated. A plurality of label edge routers that forward and delete the labels from the received labeled user packets and forward them to the terminal of the user network, and the receiving side when receiving labeled user packets transferred from these label edge routers A route server that transfers the label specifying the transfer route to the label edge router to the user packet, and the label edge router and the route server are connected in a network, and the received user packet with label corresponds to the label. It consists of a label switch router that forwards along the forwarding path In the bell switching network, the route server does not pass through the route server from the source label edge router to the destination label edge router of the user packet included in the labeled user packet based on the received labeled user packet. The cut-through route label specifying means for specifying the cut-through route label indicating the cut-through route for transferring the user packet to the user, and the cut-through data including the cut-through route label and the destination address of the user packet as the originating side Cut-through data notification means for notifying the label edge router, the label edge router from the label edge router to the destination label edge router based on the cut-through path label and the destination address included in the received cut-through data Cut When a user packet is transmitted to a desired terminal, a cut-through path label indicating a cut-through path corresponding to the destination address of the terminal is added to the user packet and transferred. And a packet transfer means.

  At this time, the route server is provided with a passing packet counting means for counting the number of user packets transferred by changing the label for each pair of the destination address of the user packet and the label, and a cut-through data notifying means. Thus, when the number of received user packets with labels reaches a predetermined criterion value, the cut-through data may be notified to the originating label edge router.

  Also, purge data for notifying the label edge router of the purge data including the cut-through path label added to the received labeled user packet and the destination address of the user packet to the originating label edge router of the user packet A notification means is provided, and the cut-through path update means deletes the cut-through path setting from the label edge router to the destination label edge router based on the cut-through path label and the destination address included in the received purge data. You may do it.

  Further, the purge data is notified by the purge data notification means when the desired terminal as the destination of the user packet included in the received labeled user packet is not connected to the user network accommodated in the label edge router. You may make it notify to an edge router.

  In addition, the route server according to the present invention forwards a user packet transmitted from a terminal of a user network accommodated to a desired terminal and adds a label for specifying the transfer route, and receives the received labeled user. Multiple label edge routers that delete labels from packets and transfer them to the terminals of the user network, and these label edge routers and route servers are connected in a network, and the received user packets with labels are transferred along the transfer route corresponding to the labels. When a user packet with a label transferred from a label edge router is received, a label that identifies a transfer route to the label edge router on the receiving side is used as the user packet. A route server that forwards By referring to a label management table that manages information on a set of a label indicating the originating and destination label edge routers and a label indicating a cut-through path connecting them based on the labeled user packet. Cut-through route label specifying means for specifying a cut-through route label indicating a cut-through route for transferring a user packet from the originating label edge router to the called label edge router without passing through the route server, and the originating label As information for setting the cut-through route from the edge router to the destination label edge router, the cut-through data including the cut-through route label and the destination address of the user packet included in the labeled user packet is used as the calling label. Cut-through data notification to the edge router It is intended and means.

  At this time, there is provided a passing packet counting means for counting the number of user packets transferred by changing the label for each set of the destination address of the user packet and the cut-through label, and the cut-through data notifying means The cut-through data may be notified to the originating label edge router only when the number of received user packets with labels reaches a predetermined determination reference value.

  A label edge router according to the present invention includes a label switch router that connects a plurality of label edge routers and a route server in a network, and transfers received user packets with labels through a transfer path corresponding to the labels, and a label edge router. When a user packet with a label transferred from is received, it is used in a label switching network consisting of a route server that transfers a label specifying the transfer route to the label edge router on the receiving side by transferring it to the user packet, A user packet sent from the terminal of the user network to be accommodated is forwarded by adding a label for specifying the transfer route to the user packet addressed to the desired terminal, and the label is deleted from the received user packet with the label and the user network Label edge router that forwards to the terminal Based on the cut-through data including the cut-through route label and destination address sent from the destination server, the user packet to the terminal having the destination address is routed from the label edge router to the predetermined destination label edge router via the route server. When a user packet is transmitted to a desired terminal, the cut-through path label indicating the cut-through path corresponding to the destination address of the terminal is And a packet transfer means for transferring in addition to the user packet.

  At this time, purge data including the cut-through path label added to the received labeled user packet and the destination address of the user packet included in the labeled user packet is used as the source label edge of the labeled user packet. A purge data notification means for notifying the router is provided, and the cut-through path update means deletes the cut-through path setting to the destination label edge router based on the cut-through path label and destination address included in the received purge data. You may make it do.

  Further, the purge data is notified by the purge data notification means when the desired terminal as the destination of the user packet included in the received labeled user packet is not connected to the user network accommodated in the label edge router. You may make it notify to an edge router.

According to the present invention, a cut-through path can be set between arbitrary label edge routers as necessary. Therefore, compared to the case where packet transfer routes are set in advance between all label edge routers, the minimum necessary number of transfer routes that each label edge router should have can be reduced. The required storage capacity can be reduced. Thereby, even when a large-scale packet communication network is configured, a small label edge node can be easily connected, and an increase in the size and cost of the label edge router can be suppressed.
Compared to a network configuration in which a specific label edge router is positioned exclusively for relay, the label edge router is used as a hub, and each label edge router that accommodates user terminals is connected in a hub-and-spoke manner, the network is connected to a specific node. Traffic concentration can be avoided, and deterioration of transfer performance of the entire network can be avoided.

Next, embodiments of the present invention will be described with reference to the drawings.
[Configuration of label switching network]
First, the configuration of a label switching network according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a configuration of a large-scale packet communication network to which a label switching network according to an embodiment of the present invention is applied.
Hereinafter, a case where an MPLS (Multi Protocol Label Switching) network is used as the label switching network will be described as an example.

This large-scale packet communication network is composed of an MPLS network 1 and user networks 2-9. The MPLS network 1 includes a route server 10 and label edge routers 11 to 14, and the terminals 15 to 22 are accommodated in the label edge routers 11 to 14 via user networks 2 to 9 and links 101 to 108, respectively. ing.
The label edge routers 11 to 14 are connected to each other by LSP (Label Switched Path) 23 to 26 provided with the route server 10.

  In the present embodiment, the route server 10 forwards the label edge routers exchanged between the label edge routers 11 to 14, and the user server issues the user packet in response to the traffic demand of the user packet. By notifying the label edge router of the cut-through data, the LSP 28 to the MPLS network 1 can be used as a cut-through path that connects the calling label edge router and the called label edge router without passing through the route server. 31 is set automatically.

[Physical model of label switching network]
Next, a physical model of the label switching network according to the present invention will be described with reference to FIG. FIG. 2 is a block diagram showing a configuration example of the MPLS network 1 as a label switching network according to the present invention.
The MPLS network 1 includes a route server 10, label edge routers 11 to 14, and label switch routers 201 to 204.

The label switch routers 201 to 204 are communication devices that identify an output link of a received frame from the header label of the received frame and transfer the frame to the output link.
The label edge router 11 is connected to the label switch router 201 via a link 109, connected to the label switch router 202 via a link 110, connected to the user network 2 via a link 101, and connected to the user network 3 via a link 102.
The label edge router 12 is connected to the label switch router 201 via a link 111, connected to the label switch router 202 via a link 112, connected to the user network 4 via a link 103, and connected to the user network 5 via a link 104. .

The label edge router 13 is connected to the label switch router 203 via a link 113, connected to the label switch router 204 via a link 114, connected to the user network 6 via a link 105, and connected to the user network 7 via a link 106.
The label edge router 14 is connected to the label switch router 203 via a link 115, connected to the label switch router 204 via a link 116, connected to the user network 8 via a link 107, and connected to the user network 9 via a link 108.

The route server 10 is connected to the label switch router 201 via a link 117, and is connected to the label switch router 203 via a link 118.
The label switch router 201 is connected to the label switch router 202 via a link 119, and is connected to the label switch router 203 via a link 120.
The label switch router 204 is connected to the label switch router 202 via a link 121 and is connected to the label switch router 203 via a link 122.

In FIG. 1 described above, the LSP 23 is realized by, for example, the link 109, the label switch router 201, and the link 117, and the LSP 25 is realized by, for example, the link 113, the label switch router 203, and the link 118.
The LSP 28 is realized by, for example, the link 109, the label switch router 201, the link 120, the label switch router 203, and the link 113.

[Root server configuration]
Next, the configuration of the route server 10 according to the embodiment of the present invention will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration example of the route server 10 according to the embodiment of the present invention.
The route server 10 includes a received packet processing unit 33, a packet processing unit 34, a forwarding table processing unit 35, a transmission packet processing unit 37, a label information management unit 38, and a labeled user packet transmission destination change notification unit 42. Yes.
Among these, the received packet processing unit 33, the packet processing unit 34, the forwarding table processing unit 35, and the label information management unit 38 have a function equivalent to a label specifying means for cut-through route, and change the user packet transmission destination with a label. The notification unit 42 has a function corresponding to cut-through data notification means. A later-described passing packet number counting unit 43 has a function corresponding to passing packet counting means.

The received packet processing unit 33 extracts the user packet by removing the label from the received user packet with label, the link when the user packet is received, and the removed label, label information management described later A function of notifying the transmission source information extraction unit 40 of the unit 38.
The packet processing unit 34 has a function of extracting the destination address from the user packet extracted by the received packet processing unit 33.

The transfer table processing unit 35 has a transfer table 36. The forwarding table 36 has a function of deriving a destination address of a user packet, a label having identification information of a destination label edge router accommodating a terminal having the destination address, and an output link thereof.
The forwarding table processing unit 35 is a function for deriving a label having identification information of a destination label edge router accommodating a terminal having the destination address and its output link from the destination address of the user packet extracted by the packet processing unit 34 have.

The label information management unit 38 includes a label management table 39, a transmission source information extraction unit 40, and an address resolution information extraction unit 41.
The label management table 39 has a function of mutually guiding information on a label and a pair of label edge routers at both ends of the transfer path of the labeled user packet.

In this configuration example, by allowing reverse lookup of the table, a function for deriving a set of label edge routers at both ends of the transfer route of the labeled user packet from the label, and a transfer route from the set of label edge routers at both ends It has a function of deriving the label of the user packet to be used.
If reverse table lookup is not allowed, two types of label management tables comprising a table for deriving a set of label edge routers at both ends from a label and a table for deriving a label from the set of label edge routers at both ends are provided. It is necessary to possess.

The transmission source information extraction unit 40 receives the label and link information removed by the reception packet processing unit 33, and uses the label and label management table 39 to obtain information on the set of the calling label edge router and the route server itself for the label. The function of identifying the originating label edge router of the user packet to which the label has been attached, and the label management table 39, the originating label edge router is made the called label edge router, and the route server itself is It has a function of deriving a label to be added when the calling side is selected.
The address resolution information extraction unit 41 has a function of extracting a label having identification information of the called label edge router searched by the forwarding table processing unit 35.

  The label information management unit 38 uses the transmission source information extraction unit 40 to specify the originating label edge router of the received labeled user packet, and the address resolution information extraction unit 41 receives the received labeled user packet. The function of identifying the label edge router and the label management table 39 indicate a cut-through path from the above-mentioned combination of the source side label edge router and the destination side label edge router to the destination side label edge router. And a function for specifying a label.

  Further, the label information management unit 38 adds the received labeled user packet to the user packet when the source label edge router of the received labeled user packet is set as the destination side and the route server itself is set as the source side. The function of identifying the label to be transmitted, the label identified by the transmission source information extraction unit 40, the destination address of the user packet, and the calling label edge router cut through the destination label edge router that accommodates the destination address. It has a function of notifying cut-through data composed of label information for transfer together with link information received from the received packet processing unit 33 by the transmission source information extraction unit 40 to the user packet transmission destination change notification unit 42 with label. doing.

The labeled packet transmission destination change notification unit 42 includes a passing packet count unit 43.
The passing packet count unit 43 has a function of counting how many times the cut-through data having the same information is notified when the cut-through data is received from the label information management unit 38.

In this configuration example, the label specified by the label information management unit 38 using the transmission source information extraction unit 40, the destination address of the user packet specified by the label information management unit 38 using the label management table 39, and the destination that stores the destination address. It is implemented by a table that derives a reception counter for a pair with a label for cut-through transfer to the side label edge router.
At this time, it is possible to count how many times the cut-through data is notified by incrementing the reception counter of the corresponding entry by 1 every time the cut-through data is received. Each entry is provided with a timer, and the count value is reset every predetermined period, for example, 60 seconds.

The user packet transmission destination change notifying unit with label 42 is the destination address of the user packet described in the cut-through data regarding the cut-through data counted by the passing packet number counting unit 43 at a predetermined determination reference value or more. And the label for cut-through transfer to the destination label edge router that accommodates the destination address are generated as cut-through data, and the label information management unit 38 extracts the source information from the cut-through data. The label introduced by the unit 40 is added, the link information notified together with the cut-through data from the label information management unit 38 is set as output link information, and the cut-through data frame with label and the output link information are notified to the transmission packet processing unit 37 By doing so, the transmission packet processing unit 3 And it has a function of outputting the MPLS network 1 from.
In this configuration example, 1000 times is used as the determination reference value.

  The transmission packet processing unit 37 adds a label having the identification information of the destination label edge router, the destination address of which is derived by the forwarding table processing unit 35, to the user packet extracted by the reception packet processing unit 33, and the label again. A function of outputting the added labeled user packet to the link corresponding to the called label edge router guided by the forwarding table processing unit 35, and the labeled cut-through data received from the labeled user packet transmission destination change notification unit 42 A function of outputting the frame to a link indicated by the output link information received at the same time.

  Thus, when the route server 10 receives the packet between the label edge routers, the route server 10 identifies the source label edge router and the destination label edge router, and from the label management table 39, the source label edge router to the destination label. Identify the label for cut-through transfer to the edge router, and notify the destination label edge router of the destination address of the user packet and the label set information for cut-through transfer to the destination label edge router Thus, a cut-through path can be generated between the originating label edge router and the receiving label edge router.

  Next, the label management table 39 used in the route server 10 will be described with reference to FIGS. FIG. 4 is a configuration example of the label management table 39 used in the route server 10. FIG. 5 is a configuration example of the label management table 39 (for reverse lookup) used in the route server 10.

The label management table 39 of the route server 10 has a function of mutually guiding information on a label and a pair of label edge routers at both ends of a transfer path corresponding to the label. This configuration example has a function of deriving a set of label edge routers at both ends of a label and a function of deriving a label with respect to a set of label edge routers at both ends by allowing reverse table lookup.
If reverse table lookup is not allowed, it is necessary to have another label management table for guiding labels to the label edge routers at both ends as shown in FIG. 5 together with the label management table shown in FIG. is there.

Next, the forwarding table 36 used in the route server 10 will be described with reference to FIG. FIG. 6 is a configuration example of the transfer table 36 used in the route server 10.
The forwarding table 36 has a function of deriving a label indicating the destination label edge router and its output link for the destination address.

Next, the passing packet number counting unit 43 of the route server 10 will be described with reference to FIG. FIG. 7 is a configuration example of the passing packet count unit 43 of the route server 10.
The passing packet count unit 43 counts how many times the cut-through data having the same information is notified when the cut-through data is received from the label information management unit 38, that is, performs a label change. The number of user packets transferred in this way is counted for each set of the destination address of the user packet and its label. For example, it can be implemented by a table as shown in FIG.

[Label Edge Router Configuration]
Next, the label edge routers 11 to 14 installed in the label switching network together with the route server 10 of the present invention will be described with reference to FIG. FIG. 8 is a block diagram showing the configuration of the label edge routers 11-14.
The label edge routers 11 to 14 include a packet classification unit 44, a core packet control unit 45, an access packet control unit 46, a route deletion notification generation unit 55, and a packet transmission processing unit 57.
Among these, the core packet control unit 45 and the access packet control unit 46 have a function corresponding to a cut-through path updating unit, and the access packet control unit 46 has a function corresponding to a packet transfer unit. The core packet control unit 45, the access packet control unit 46, and the route deletion notification generation unit 55 have a function corresponding to the purge data notification unit.

  The packet classification unit 44 identifies whether the received packet and frame are a labeled user packet received from the MPLS network 1 or a user packet received from the user network, and a core packet control unit together with link information received from the labeled user packet And a function of transferring the user packet to the access packet control unit 46.

The access packet control unit 46 includes an access packet processing unit 47, a core transfer table processing unit 48, and a label addition unit 49.
The access packet processing unit 47 has a function of receiving a user packet from the packet classification unit 44 and extracting a destination address of the user packet.
The core transfer table processing unit 48 has a core transfer table 50.
The core forwarding table 50 has a function of deriving a label having identification information of a forwarding destination label edge router corresponding to each destination address of the user packet and its output link.

  In the present configuration example, when the destination address of the user packet is accommodated, the entry corresponding to the destination address is not described in the table. As another method, when the destination address of the user packet is accommodated by itself, a method that does not describe the additional label and output link of the entry corresponding to the destination address, or the flag corresponding to the entry corresponding to the destination address is set. It is possible to write.

  In addition, the core forwarding table 50 includes a fixed route information entry part that holds a route addressed to the route server, and a cut-through route that is transferred without passing through the route server to the destination label edge router that accommodates the terminal having the destination address. And a cache route information entry part that holds

  The core forwarding table processing unit 48 searches the core forwarding table 50 to derive a label to be added to the user packet and its output link from the destination address of the user packet extracted by the access packet processing unit 47, and the core When searching the forwarding table 50, the cache path information entry part is searched and then the fixed path information entry part is searched, and when the core forwarding table 50 is searched, the destination address as a search key is stored by itself. A function of transferring the user packet to a core packet processing unit 52 to be described later.

  Furthermore, when the core forwarding table processing unit 48 receives an inquiry from the route deletion notification generating unit 55 described later about whether or not the label edge router in which the terminal of the destination address of a user packet is accommodated is itself, The core forwarding table 50 is searched, and if the label edge router 13 itself is identified as being accommodated, nothing is performed. Otherwise, a function for notifying the route deletion notification generating unit 55, and a core packet to be described later When cut-through data is transferred from the processing unit 52, a function for adding entry information described in the cut-through data to the cache path information entry unit of the core transfer table 50 and transfer of purge data from the core packet processing unit 52 Cache of the core transfer table 50 corresponding to the entry information described in the purge data when And it has a function of deleting an entry of the route information entry unit.

  In this configuration example, when the core transfer table 50 is searched, if an entry corresponding to the destination address as the search key cannot be detected, it is identified that the destination address is accommodated.

  The label adding unit 49 adds the label to be added to the user packet, which is calculated by the core transfer table processing unit 48, to the corresponding user packet, and the user packet with label generated by itself to the core transfer table processing unit. Along with the output link information corresponding to the user packet calculated in 48, it has a function of transferring to the packet transmission processing unit 57 described later.

The core packet control unit 45 includes a label processing unit 51, a core packet processing unit 52, and an access transfer table processing unit 53.
The label processing unit 51 has a function of removing the labeled user packet and frame label received from the packet classification unit 44.
The core packet processing unit 52 has a function of extracting a destination address of the user packet from the user packet, a function of transferring the corresponding data to the core transfer table processing unit 48 when the received data is cut-through data, When the received packet is purge data described later, it has a function of transferring the corresponding data to the core transfer table processing unit 48.

The access transfer table processing unit 53 has an access transfer table 54.
The access transfer table 54 has a function of deriving an output link to the user network corresponding to each destination address included in the user packet.
The access transfer table processing unit 53 searches the access transfer table 54, thereby deriving an output link for the user packet from the destination address of the user packet extracted by the core packet processing unit 52, and the access transfer of the user packet. If the entry is not detected when searching the access transfer table 54 and the function for transferring to the packet transmission processing unit 57 described later together with the output link information corresponding to the user packet calculated from the table 54 It has a function of transferring the user packet, the label added to the user packet and removed by the label processing unit 51, and the link information received from the user packet to the route deletion notification generating unit 55 described later. Yes.

The route deletion notification generation unit 55 has a cut-through label management table 56.
The cut-through label management table 56 has a function of deriving information on a set of labels and label edge routers at both ends of the transfer path.
This configuration example has a function of deriving a set of label edge routers at both ends of a label and a function of deriving labels to label edge routers at both ends by allowing reverse table lookup. When reverse table lookup is not permitted, the table has two types of cut-through label management tables 56: a table for deriving a label edge router pair at both ends of a label and a table for deriving a label for label edge routers at both ends. There is a need to.

  When the route deletion notification generation unit 55 receives the user packet, the label added to the user packet, and the link information that received the user packet from the access transfer table processing unit 53, the core transfer table processing unit 48, inquires whether or not the label edge router accommodating the terminal of the destination address of the user packet is itself, and if the notification is not received from the core forwarding table processing unit 48, nothing is done. Purge data describing the destination address and label of the user packet received from the access transfer table processing unit 53 is created, and the calling side label edge router and the called side label edge router corresponding to the label are determined from the cut-through label management table 56. From the cut-through label management table 56, Specify the label for purging when the originating label edge router is the receiving label edge router, and the originating label edge router is the originating label edge router, generate the purge data frame by adding the purge label to the purge data, The purge data frame and the link information received from the access transfer table processing unit 53 are transferred to the packet transmission processing unit 57.

  The packet transmission processing unit 57 outputs the labeled user packet received from the label adding unit 49 to the link destination received from the label adding unit 49 and the user packet received from the access transfer table processing unit 53. At that time, the function of outputting to the link destination received from the access transfer table processing unit 53 and the labeled packet having the purge data received from the route deletion notification generating unit 55 are received from the route deletion notification generating unit 55 at that time. It has a function to output to the front.

As a result, when the label edge routers 11 to 14 are notified of cut-through data consisting of a combination of the destination address of the user packet and the label for cut-through transfer to the destination label edge router from the route server 10, By adding the content of the cut-through data to the cache part of the core transfer table, it becomes possible to set a cut-through path between itself and the destination label edge router.
Also, when the destination terminal of the received user packet is not accommodated, a purge data frame requesting deletion of route information is transmitted to the calling label edge router, and the transfer used by the calling label edge router By deleting the cache entry in the table, it becomes possible to delete a cut-through path that has become inappropriate due to path fluctuations.

Next, the core forwarding table 50 used in the label edge routers 11 to 14 will be described with reference to FIG. FIG. 9 is a configuration example of the core forwarding table 50 used in the label edge routers 11 to 14.
The core forwarding table 50 has a function of deriving a label having identification information of a forwarding destination label edge router corresponding to each destination address of the user packet and its output link.
In addition, the core forwarding table 50 is a cut-through in which a fixed route information entry part holding a route addressed to the route server 10 and a destination label edge router accommodating a terminal having a destination address are transferred without going through the route server. It consists of a cache route information entry part that holds the route.

  In the present configuration example, when the destination address of the user packet is accommodated, the entry corresponding to the destination address is not described in the table. As another method, when the destination address of the user packet is accommodated by itself, a method that does not describe the additional label and output link of the entry corresponding to the destination address, or the flag corresponding to the entry corresponding to the destination address is set. It is possible to write.

Next, the access transfer table 54 used in the label edge routers 11 to 14 will be described with reference to FIGS. 10 and 11. FIG. 10 is a configuration example of the access transfer table 54 used in the label edge router 11. FIG. 11 is a configuration example of the access transfer table 54 used in the label edge router 13.
The access transfer table 54 has a function of leading an output link to the user network corresponding to each destination address included in the user packet.

Next, the cut-through label management table 56 used in the label edge routers 11 to 14 will be described with reference to FIGS. FIG. 12 is a configuration example of the cut-through label management table 56 used in the label edge router 11. FIG. 13 is a configuration example of the cut-through label management table 56 (for reverse lookup) used in the label edge router 11.
The cut-through label management table 56 has a function of deriving information on a label and a set of label edge routers at both ends of the transfer path.

  This configuration example has a function of deriving a set of label edge routers at both ends of a label and a function of deriving a label to label edge routers at both ends by allowing reverse table lookup. When reverse table lookup is not allowed, the cut-through label management table shown in FIG. 12 and another type of cut-through label management table for guiding labels to the label edge routers at both ends as shown in FIG. There is a need to.

[Basic operation of label switching network]
Next, a basic operation of the label switching network (MPLS network) according to the present embodiment will be described with reference to FIGS. FIG. 14 is a sequence diagram showing a packet transfer operation of the MPLS network 1 according to the present embodiment. FIG. 15 is an explanatory diagram showing the forwarding process for the MPLS network addressed by the originating label edge router 11. FIG. 16 is an explanatory diagram showing packet transfer processing of the route server 10. FIG. 17 is an explanatory diagram showing transfer processing addressed to the user network of the destination label edge router 13.

In the MPLS network 1, when a user packet exchanged between terminals is transferred, the user packet is once converted into a labeled user packet and transferred by a packet transfer operation shown in FIG.
In the following, from the terminal 16 connected to the label edge router 11 via the user network 3 in FIG. 1 to the terminal 20 connected to the label edge router 13 via the user network 7 via the route server 10. A case where a desired user packet is transferred will be described as an example.

[Transfer processing of the label edge router to the MPLS network]
First, with reference to FIG. 14 and FIG. 15, a description will be given of the forwarding processing for the MPLS network in the label edge router 11 on the originating side.
Note that the label edge router 11 has the core transfer table 50 of FIG. 9 described above.

The label edge router 11 receives the user packet 302 transmitted from the terminal 16 via the user network 3 by the packet classification unit 44 (step 500). In this user packet 302, the IP address “user # 6” of the terminal 20 is set as the destination IP address of the user packet, and the IP address “user # 2” of the terminal 16 is set as the source IP address. Yes.
The packet classification unit 44 transfers the received user packet 302 to the access packet processing unit 47.

The access packet processing unit 47 receives the user packet 302 from the packet classification unit 44, extracts the destination address # 6 from the received user packet 302, notifies the extracted destination address # 6 to the core forwarding table processing unit 48, The user packet 302 is transferred to the label adding unit 49.
The core transfer table processing unit 48 receives the notification of the destination address # 6 from the access packet processing unit 47, and searches the cache route information of the core transfer table 50 using the destination address # 6 as a search key. At this time, since there is no entry of the destination address # 6 in the example of the core transfer table 50 of FIG. 9, the fixed route information in the core transfer table 50 is searched next, and the additional label # 5 and the output link 109 are specified. The additional label # 5 and the output link 109 are notified to the label adding unit 49 (step 501).

The label adding unit 49 receives the user packet 302 from the access packet processing unit 47 and receives the notification of the additional label # 5 and the output link 109 from the core transfer table processing unit 48, and adds the label # 5 to the user packet 302. As a result, the labeled user packet 301 is generated, and the information of the labeled user packet 301 and the link 109 is transferred to the packet transmission processing unit 57 (step 502).
The packet transmission processing unit 57 receives the information on the labeled user packet 301 and the link 109 from the label adding unit 49, and outputs the labeled user packet 301 to the link 109 (step 503).

  Through the above processing, the calling-side label edge router 11 encapsulates the user packet 302 received from the user network 3 into the labeled user packet 301 and transfers it to the MPLS network 1.

[Route server packet forwarding operation]
Next, the packet transfer process of the route server 10 will be described with reference to FIGS. 14 and 16.
It is assumed that the route server 10 has the transfer table 36 shown in FIG.

The route server 10 receives the labeled user packet 301 from the link 117 by the received packet processing unit 33.
The received packet processing unit 33 extracts the user packet 302 by removing the label from the labeled user packet 301, and transfers the user packet 302 to the packet processing unit 34 (step 510).
The packet processing unit 34 receives the user packet 302 from the received packet processing unit 33, extracts the destination address # 6 from the received user packet 302, notifies the transfer table processing unit 35 of the extracted destination address # 6, and The packet 302 is transferred to the transmission packet processing unit 37.

The forwarding table processing unit 35 receives the notification of the destination address # 6 from the packet processing unit 34, specifies the additional label # 3 and the output link 118 by searching the forwarding table 36 using the destination address # 6 as a search key, The additional label # 3 and the output link 118 are notified to the transmission packet processing unit 37 (step 511).
The transmission packet processing unit 37 receives the user packet 302 from the packet processing unit 34, receives the notification of the additional label # 3 and the output link 118 from the transfer table processing unit 35, and adds the label # 3 to the user packet 302. Thus, a labeled user packet 303 is generated (step 512), and the labeled user packet 303 is output to the link 118 (step 513).

  Through the above processing, the route server 10 removes the label from the labeled user packet 301 from the MPLS network 1, refers to the destination address of the user packet 302, searches the forwarding table 36, and adds the obtained label. As a result, the labeled user packet 303 with the label changed is generated and transferred to the MPLS network 1.

[Label Edge Router Transfer to User Network]
Next, the user network transfer process of the label edge router 13 on the called side will be described with reference to FIGS.
It is assumed that the label edge router 13 has the access transfer table 54 shown in FIG.

The label edge router 13 receives the labeled user packet 303 by the packet classification unit 44.
The packet classification unit 44 transfers the information of the labeled user packet 303 and the reception link 113 to the label processing unit 51.
The label processing unit 51 receives the labeled user packet 303 from the packet classification unit 44, extracts the user packet 302 by removing the label # 3 from the received labeled user packet 303, and extracts the user packet 302 as a core packet. The data is transferred to the processing unit 52 (step 520).

The core packet processing unit 52 receives the user packet 302 from the label processing unit 51, extracts the destination address # 6 from the user packet 302, notifies the access transfer table processing unit 53 of the extracted destination address # 6, and receives the user packet 302 is transferred to the access transfer table processing unit 53.
The access transfer table processing unit 53 receives the notification of the destination address # 6 from the core packet processing unit 52, specifies the output link 106 by searching the access transfer table 54 using the destination address # 6 as a search key, and specifies the core packet. The user packet 302 is received from the processing unit 52, and the information of the user packet 302 and the output link 106 is transferred to the packet transmission processing unit 57 (step 521).

The packet transmission processing unit 57 receives the user packet 302 and the information of the output link 106 from the access transfer table processing unit 53, and outputs the user packet 302 to the link 106 (step 522).
Through the above processing, the label edge router 13 decapsulates the labeled user packet 303 received from the MPLS network 1 into the user packet 302 and transfers the packet to the user network 7.

  In this way, the user packet 302 transmitted from the terminal 16 is encapsulated in the labeled user packet 301 by the originating label edge router 11 and transferred to the route server 10 in the MPLS network 1 (steps 500 to 503). ). In response to this, the route server 10 changes the label of the labeled user packet 301 and transfers it to the called label edge router 13 as a labeled user packet 303 (steps 510 to 513). The called label edge router 13 transfers the original user packet 302 obtained by decapsulating the labeled user packet 301 to the terminal 20 (steps 520 to 522).

[Cut-through route setting operation of label switching network]
Next, the cut-through path setting operation of the label switching network (MPLS network) according to the present embodiment will be described with reference to FIGS. FIG. 18 is a sequence diagram showing the cut-through path setting operation of the MPLS network 1. FIG. 19 is an explanatory diagram showing cut-through data notification processing of the route server 10. FIG. 20 is an explanatory diagram showing a cut-through route setting process of the originating label edge router 11.

In the MPLS network 1, when a user packet exchanged between terminals is transferred by the route server 10, cut-through data is notified from the route server 10 to the calling-side label edge router 11 as necessary, via the route server 10. By setting a cut-through route that connects between the calling side and the destination label edge router without setting, the user packet is transferred via the cut-through route thereafter, and the processing load on the route server 10 is adjusted.
In the following, a desired user packet is transferred from the terminal 16 connected to the label edge router 11 via the user network 3 in FIG. 1 to the terminal 20 connected to the label edge router 13 via the user network 7. An example of the case will be described.

[Route server cut-through data notification processing]
First, the cut-through data notification process of the route server 10 will be described with reference to FIGS. 18 and 19.
It is assumed that the route server 10 has the above-described label management table in FIG. 4, the forwarding table in FIG. 6, and the passing packet count section (table) in FIG.
This cut-through data notification process is executed in parallel with the packet transfer process of the route server 10 in FIGS. 14 and 16 described above.

The route server 10 receives the labeled user packet 301 from the link 117 by the received packet processing unit 33 (step 530).
The received packet processing unit 33 extracts the user packet 302 by removing the label from the labeled user packet 301 and transfers the user packet 302 to the packet processing unit 34. At the same time, the received label # 5 and the received link 117 are The information is notified to the transmission source information extraction unit 40 of the label information management unit 38 (step 531).

The packet processing unit 34 receives the user packet 302 from the received packet processing unit 33, extracts the destination address # 6 from the received user packet 302, and notifies the transfer table processing unit 35 of the extracted destination address # 6.
The transfer table processing unit 35 receives the notification of the destination address # 6 from the packet processing unit 34 and searches the transfer table 36 using the destination address # 6 as a search key, thereby adding the destination address # 6 and the cut-through transfer addition. Label # 3 is notified to the address resolution information extraction unit 41 of the label information management unit 38 (step 532).

In the transmission source information extraction unit 40, the label information management unit 38 receives the label # 5 and the reception link 117 added to the labeled user packet 301 from the reception packet processing unit 33, and uses the label # 5 as a search key to label By searching the management table 39, the core # 2 indicating the originating label edge router is specified (step 533).
Further, the address resolution information extraction unit 41 receives the destination address and the additional label # 3 from the transfer table processing unit 35, and searches the label management table 39 using the label # 3 as a search key to indicate the destination label edge router. Core # 4 is identified (step 534).

Then, the label management table 39 is reversely retrieved from the search key in which the calling label edge router is the core # 2 and the called label edge router is the core # 4, so that the calling label edge router is called the called label edge. A label # 7 for cut-through transfer that realizes cut-through transfer to the router is specified (step 535).
Further, by reversely retrieving the label management table 39 from the search key in which the core # 2 indicating the calling side label edge router is set as the called side label edge router and the core # 1 indicating the route server itself is set as the calling side label edge router. The label # 1 necessary for transferring the cut-through data to the originating label edge router 11 is specified (step 536).

  Here, the link 117 received from the received packet processing unit 33 in the transmission source information extraction unit 40, the destination address # 6 received from the transfer table processing unit 35 in the address resolution information extraction unit 41, and the cut-through specified by the label management table 39 The label # 7 for transfer and the label # 1 used to transmit the cut-through data composed of the destination address # 6 and the label # 7 are notified to the labeled user packet transmission destination change notification unit 42.

  The user packet transmission destination change notification unit with label 42 receives from the label information management unit 38 the cut 117 data including the link 117, the destination address # 6 and the label # 7, and the label # 1 for transmitting the cut through data. Then, using the destination address # 6, label # 7, and label # 1 as search keys, the passing packet count counter 43 is searched, and the counter value of the corresponding entry is incremented by one.

At this time, if the counter value exceeds a determination reference value, for example, 1000 times, the cut-through data including the destination address # 6 and the label # 7 is added with the label # 1 for transmitting the cut-through data, and the cut is performed. The through data frame 304 is generated and transferred to the transmission packet processing unit 37 together with the information on the link 117 received from the label information management unit 38.
The transmission packet processing unit 37 receives information on the cut-through data frame 304 and the link 117 from the labeled user packet transmission destination change notification unit 42, and outputs the cut-through data frame 304 to the link 117 (step 537).

Through the above operation, the route server 10 searches the label management table 39 that manages information on the combination of the label and the label edge routers at both ends of the transfer path, and identifies the originating label edge router 11 from the removed label. At the same time, the destination label edge router 13 is identified from the added label. Also, the label management table for managing the information of the pair of label edge routers and labels at both ends is searched, and the label from the calling label edge router to the called label is searched from the set of the calling label edge router and the called label edge router. Specify the label for cut-through transfer to the edge router.
The originating label edge router 11 is notified of cut-through data comprising a set of a destination address of the user packet and a label for cut-through transfer from the originating label edge router to the terminating label edge router.

[Label Edge Router Cut-Through Route Setting Operation]
Next, with reference to FIG. 18 and FIG. 20, the cut-through route generation processing of the label edge router 11 on the originating side will be described.
Note that the label edge router 11 has the core transfer table 50 of FIG. 9 described above.

The label edge router 11 receives the cut-through data frame 304 by the packet classification unit 44.
The packet classification unit 44 transfers the information of the cut-through data frame 304 and the reception link 109 to the label processing unit 51.
The label processing unit 51 receives the cut-through data frame 304 from the packet classification unit 44, extracts the cut-through data 305 by removing the label # 1 from the cut-through data frame 304, and performs the core packet processing on the cut-through data 305. The data is transferred to the unit 52 (step 540).

The core packet processing unit 52 receives the cut-through data 305 from the label processing unit 51 and transfers the cut-through data 305 to the core transfer table processing unit 48.
The core transfer table processing unit 48 receives the cut-through data 305 from the core packet processing unit 52, and uses the destination address # 6 described in the cut-through data as the destination address as an entry indicating the cache path information of the core transfer table 50. At the same time, an entry with the cut-through label # 7 described in the cut-through data as an additional label is added (step 541).

  FIG. 21 shows a configuration example of the updated core transfer table 50. As a result of this operation, the core forwarding table 50 has the entry contents shown in FIG. 21 from FIG. 9, and as a cut-through path that connects the calling label edge router 11 and the called label edge router 13 without going through the route server 10. Thus, the LSP 28 in FIG. 1 is set.

  Further, after the cut-through path setting process, when the label edge router 11 receives the user packet 302 from the terminal 16 (step 550), the core forwarding table processing unit 48 sends the destination address # 6 from the access packet processing unit 47. Upon receipt of the notification, the cache path information in the core transfer table 50 is searched using the destination address # 6 as a search key to identify the cut-through transfer additional label # 7 and the output link 109 (step 551), and the additional label The label adding unit 49 is notified of # 7 and the output link 109.

The label adding unit 49 receives the user packet 302 from the access packet processing unit 47, receives the notification of the additional label # 5 and the output link 109 from the core transfer table processing unit 48, and adds the label # 7 to the user packet 302. Thus, a labeled user packet is generated, and the labeled user packet and the information of the link 109 are transferred to the packet transmission processing unit 57 (step 552).
The packet transmission processing unit 57 receives the labeled user packet and the link 109 information from the label adding unit 49, and outputs the labeled user packet to the link 109 (step 553). As a result, the labeled user packet is transferred to the destination label edge router without going through the route server 10.

  As a result of the above operation, the calling label edge router 11 adds an entry to the core forwarding table 50 based on the cut-through data notified from the route server 10 and passes through the called label edge router 13 and the route server 10. Set the cut-through path to be connected without connecting. Then, the originating label edge router 11 encapsulates the user packet received from the user network 3 into a labeled user packet for a cut-through path and transfers the packet to the MPLS network 1.

  Thus, in the present embodiment, the route server 10 receives the user packet without the route server 10 from the source label edge router 11 to the destination label edge router 13 based on the received labeled user packet. A cut-through path label indicating a cut-through path to be transferred is specified, and cut-through data including the cut-through path label and the destination address of the user packet is notified to the originating label edge router 11 (step 530). 537), the originating label edge router 11 sets the cut-through path from the label edge router 11 to the destination label edge router 13 based on the cut-through path label and the destination address included in the received cut-through data. (Steps 540 and 541) As required between labels edge routers, it is possible to set a cut-through path.

Therefore, compared to the case where packet transfer routes are set in advance between all label edge routers, the minimum necessary number of transfer routes that each label edge router should have can be reduced. The required storage capacity can be reduced. Thereby, even when a large-scale packet communication network is configured, a small label edge node can be easily connected, and an increase in the size and cost of the label edge router can be suppressed.
Compared to a network configuration in which a specific label edge router is positioned exclusively for relay, the label edge router is used as a hub, and each label edge router that accommodates user terminals is connected in a hub-and-spoke manner, the network is connected to a specific node. Traffic concentration can be avoided, and deterioration of transfer performance of the entire network can be avoided.

[Cut-through route deletion operation of label switching network]
Next, with reference to FIGS. 22 to 24, the cut-through route deletion operation of the label switching network (MPLS network) according to the present embodiment will be described. FIG. 22 is a sequence diagram showing the cut-through path deletion operation of the MPLS network 1. FIG. 23 is an explanatory diagram showing the purge data notification process of the destination label edge router 13. FIG. 24 is an explanatory diagram showing the cut-through route deletion process of the originating label edge router 11.

  In the following, in response to the fact that the terminal 20 of FIG. 1 that is the destination of the user packet has moved from the label edge router 13 to the subordinate of the label edge router 14, the source label edge router 11 and the destination label edge router 13 are connected. A case where the cut-through path (LSP 28) to be connected is deleted will be described as an example.

In general, in packet communication networks and label switching networks, routing protocols such as OSPF (Open Shortest Path First), RIP (Routing Information Protocol), and BGP (Border Gateway Protocol) operate according to changes in the network configuration. Various forwarding tables in the router are updated.
For example, when a path change occurs in the network of FIG. 1 described above and the terminal 20 moves from the subordinate of the label edge router 13 to the subordinate of the label edge router 14, the label edge router 13 holds it by the operation of the routing protocol. The access transfer table 54 is changed to the entry contents as shown in FIG. 11 to FIG. 25, and fixed path information indicating the additional label # 3 for the destination address # 6 is added to the core transfer table 50 held by the label edge router 13. (Not shown).

[Label edge router cut-through route deletion notification operation]
In this situation, when the label edge router 13 receives the labeled user packet 306 addressed to the terminal 20, the label edge router 13 performs the following cut-through route deletion notification process.
Hereinafter, with reference to FIG. 22 and FIG. 23, the purge data notification process of the destination label edge router 13 will be described.

The label edge router 13 receives the labeled user packet 306 by the packet classification unit 44 (step 600). In this labeled user packet 306, the IP address “user # 6” of the terminal 20 is set as the destination IP address of the user packet, and the IP address “user # 2” of the terminal 16 is set as the source IP address. Has been. Further, “label # 7” corresponding to the cut-through path is added.
The packet classification unit 44 transfers the information of the labeled user packet 306 and the reception link 113 to the label processing unit 51.

The label processing unit 51 receives the information of the labeled user packet 306 and the reception link 113 from the packet classification unit 44, extracts the user packet 302 by removing the label # 7 from the received labeled user packet 306, The user packet 302 is transferred to the core packet processing unit 52 (step 601).
The core packet processing unit 52 receives the user packet 302 from the label processing unit 51, extracts the destination address # 6 from the user packet 302, notifies the access transfer table processing unit 53 of the extracted destination address # 6, and receives the user packet 302 is transferred to the access transfer table processing unit 53.

The access transfer table processing unit 53 receives the notification of the destination address # 6 from the core packet processing unit 52, receives the user packet 302 from the core packet processing unit 52, and stores the access transfer table 54 using the destination address # 6 as a search key. Search is performed (step 602). Here, since the corresponding entry does not exist in the changed access transfer table 54 shown in FIG. 25, the corresponding entry cannot be detected (step 603: YES).
Therefore, the access transfer table processing unit 53 receives the label # 7 and the information on the reception link 113 added to the user packet 302 from the label processing unit 51, and the label # 7, the information on the reception link 113, and the user packet 302. Is transferred to the route deletion notification generation unit 55.

The route deletion notification generation unit 55 receives the label # 7, the information of the reception link 113, and the user packet 302 from the access transfer table processing unit 53, and sets the destination address # 6 of the user packet 302 to the core transfer table processing unit 48. An inquiry is made as to whether the label edge router 13 itself is accommodated.
The core transfer table processing unit 48 receives the inquiry from the route deletion notification generating unit 55, and searches the core transfer table 50 using the destination address # 6 as a search key (step 610). When the corresponding entry is detected, the route deletion notification generating unit 55 is notified that the corresponding entry has been detected (step 611: YES).

The route deletion notification generation unit 55 receives the notification from the core transfer table processing unit 48 and generates purge data 308 from the destination address # 6 and the label # 7 of the user packet 302 received from the access transfer table processing unit 53 ( Step 612).
Subsequently, the core # 2 indicating the originating label edge router and the core # 4 indicating the destination label edge router corresponding to the label # 7 are identified from the cut through label management table 56 (step 613), and the cut through label is specified. From the management table 56, the purge label # 14 is specified when the calling label edge router is the called label edge router and the called label edge router itself is the calling label edge router (step 613).

Then, the route deletion notification generating unit 55 adds the purge label # 14 to the purge data 308, and transfers the information on the reception link 113 from the purge data frame 307 and the access transfer table processing unit 53 to the packet transmission processing unit 57. .
The packet transmission processing unit 57 receives the purge data frame 307 and the information of the reception link 113 from the route deletion notification generation unit 55, and outputs the purge data frame 307 to the link 113 (step 615).

  With the above operation, the destination label edge router 13 requests the originating label edge router 11 to delete the route information when it does not accommodate the destination terminal of the received labeled user packet 306. , And the cache entry in the forwarding table used by the originating label edge router 11 is deleted, so that it becomes possible to delete a cut-through path that has become inappropriate due to path fluctuation or the like.

[Label edge router cut-through route deletion]
Next, with reference to FIG. 22 and FIG. 24, the cut-through route deletion process in the label edge router 11 on the originating side will be described.
The label edge router 11 receives the purge data frame 307 by the packet classification unit 44.
The packet classification unit 44 transfers the purge data frame 307 and the information on the reception link 109 to the label processing unit 51.
The label processing unit 51 receives the purge data frame 307 from the packet classification unit 44, extracts the purge data 308 by removing the label # 14 from the purge data frame 307, and sends the purge data 308 to the core packet processing unit 52. Transfer (step 620).

The core packet processing unit 52 receives the purge data 308 from the label processing unit 51 and transfers the purge data 308 to the core transfer table processing unit 48.
The core transfer table processing unit 48 receives the purge data 308 from the core packet processing unit 52, and uses the destination address # 6 described in the purge data in the entry indicating the cache path information of the core transfer table 50 as the destination address. Then, the entry having the cut-through label # 7 described in the purge data as an additional label is deleted (step 621). As a result, the core transfer table 50 is updated from FIG. 21 to the original entry contents of FIG. 9, and the LSP 28 of FIG. 1 is deleted.

  With the above operation, the calling label edge router 11 deletes the forwarding table entry based on the route deletion information received from the called label edge router 13, that is, purge data, and thereafter, the route server transfers the corresponding user packet. Apply route via.

  In this way, the label edge router 13 sends the purge data including the cut-through path label added to the received labeled user packet and the destination address of the user packet to the originating label edge router 11 of the user packet. The label edge router 11 sets the cut-through path from the label edge router 11 to the destination label edge router 13 based on the cut-through path label and destination address of the purge data received (steps 600 to 615). (Steps 620 and 621), it is possible to delete the setting of an arbitrary cut-through route if necessary, and efficiently use the storage capacity for the forwarding route management necessary for the label edge router. it can.

In the above description, an MPLS network having four label edge routers has been described as an example of a label switching network. However, the present invention is not limited to this, and a packet is transferred using a label for specifying a transfer route. The present invention can be applied to any type of network or a network including an arbitrary number of label edge routers in the same manner as described above, and the same operational effects can be obtained.
In addition, each table described above is not limited to the configuration example in the above-described diagram, and the present invention can be applied in the same manner as described above as long as the table has the same function, and the same function and effect. Can be obtained.

It is a block diagram which shows the structure of the large-scale packet communication network to which the label switching network concerning one embodiment of this invention is applied. It is a block diagram which shows the structural example of an MPLS network as a label switching network concerning one embodiment of this invention. It is a block diagram which shows the structure of the route server concerning one embodiment of this invention. It is a structural example of the label management table used with a route server. It is a structural example of the label management table (for reverse lookup) used with a route server. It is a structural example of the transfer table used with a route server. It is an example of a structure of the passage packet number count part of a route server. It is a block diagram which shows the structure of a label edge router. It is a structural example of the core transfer table used with a label edge router. It is an example of a structure of the access transfer table used with an origination label edge router. It is an example of a structure of the access transfer table used with a callee side label edge router. It is an example of a structure of the cut-through label management table used with a label edge router. It is a structural example of the cut-through label management table (for reverse lookup) used in the label edge router. It is a sequence diagram which shows the packet transfer operation | movement of the MPLS network concerning this Embodiment. It is explanatory drawing which shows the forwarding process addressed to the MPLS network of an origination label edge router. It is explanatory drawing which shows the packet transfer process of a route server. It is explanatory drawing which shows the transfer process addressed to the user network of a receiving side label edge router. It is a sequence diagram which shows the cut-through path | route setting operation | movement of an MPLS network. It is explanatory drawing which shows the cut-through data notification process of a route server. It is explanatory drawing which shows the cut-through path | route setting process of an origination label edge router. It is an example of a structure of the core forwarding table (after update) used with a calling side label edge router. It is a sequence diagram which shows the cut-through path | route deletion operation | movement of an MPLS network. It is explanatory drawing which shows the purge data notification process of a callee side label edge router. It is explanatory drawing which shows the cut-through path | route deletion process of an origination label edge router. It is an example of a structure of the access transfer table (after an update) used with the destination label edge router.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... MPLS network, 2-9 ... User network, 10 ... Route server, 11-14 ... Label edge router, 15-22 ... Terminal, 23-32 ... LSP, 33 ... Received packet processing part, 34 ... Packet processing part, 35 ... Transfer table processing unit, 36 ... Transfer table, 37 ... Transmission packet processing unit, 38 ... Label information management unit, 39 ... Label management table, 40 ... Source information extraction unit, 41 ... Address resolution information extraction unit, 42 ... User packet transmission destination change notification section with label, 43... Passing packet count section, 44 ... packet classification section, 45 ... core packet control section, 46 ... access packet control section, 47 ... access packet processing section, 48 ... core transfer table Processing unit 49 ... Label adding unit 50 ... Core forwarding table 51 ... Label processing unit 52 ... Core packet processing unit 53 ... A Access transfer table processing unit, 54... Access transfer table, 55... Route deletion notification generation unit, 56... Cut-through label management table, 57... Packet transmission processing unit, 101-121 ... link, 201-204 ... label switch router, 301 303, 306... Labeled user packet, 302... User packet, 304... Cut-through data frame, 305... Cut-through data, 307.

Claims (9)

A user packet addressed to a desired terminal transmitted from a terminal of a user network to be accommodated is forwarded with a label for specifying a transfer route, and the user network is deleted by deleting a label from the received labeled user packet. When receiving a plurality of label edge routers to be transferred to the terminal of the terminal and a labeled user packet transferred from these label edge routers, a label for specifying a transfer route to the label edge router on the receiving side is assigned to the user packet. A label switching network comprising a route server for transferring and transferring, and a label switch router for connecting these label edge routers and route servers in a network, and transferring received user packets with labels through a transfer route corresponding to the label. ,
The root server is
Cut for transferring the user packet from the source label edge router to the destination label edge router of the user packet included in the labeled user packet without passing through the route server based on the received labeled user packet A cut-through path label specifying means for specifying a cut-through path label indicating a through path;
Cut-through data notification means for notifying the call-out label edge router of cut-through data including the cut-through path label and the destination address of the user packet;
The label edge router
Cut-through path updating means for setting a cut-through path from the label edge router to the destination label edge router based on the cut-through path label and the destination address included in the received cut-through data;
And a packet transfer means for adding a cut-through route label indicating a cut-through route corresponding to the destination address of the terminal to the user packet when transmitting the user packet to a desired terminal. Label switching network. The label switching network according to claim 1, wherein
The route server further includes a passing packet counting means for counting the number of user packets transferred by changing the label for each set of the destination address of the user packet and the label,
The cut-through data notification means notifies the cut-through data to the originating label edge router when the number of received user packets with labels reaches a predetermined determination reference value. Switching network. The label switching network according to claim 1, wherein
The label edge router
Purge data notification means for notifying purge data including a cut-through path label added to the received labeled user packet and the destination address of the user packet to the originating label edge router of the user packet;
The cut-through path updating means deletes the setting of the cut-through path from the label edge router to the destination label edge router based on the cut-through path label and the destination address included in the received purge data. Characteristic label switching network. The label switching network according to claim 3,
The purge data notifying means sends the purge data to the originating side when a desired terminal that is a destination of the user packet included in the received labeled user packet is not connected to a user network accommodated in the label edge router. A label switching network characterized by notifying a label edge router. A user packet addressed to a desired terminal transmitted from a terminal of a user network to be accommodated is forwarded with a label for specifying a transfer route, and the user network is deleted by deleting a label from the received labeled user packet. Switching that consists of a plurality of label edge routers that transfer to the terminal of the terminal, and a label switch router that connects these label edge routers and route servers in a network and forwards the received labeled user packets on the transfer path corresponding to the label. When a user packet with a label transferred from the label edge router is received and used in the network, a route server for transferring the label specifying the transfer route to the label edge router on the receiving side is transferred to the user packet. There,
Based on the received user packet with label, the label management table that manages information on a set of a label indicating the source and destination label edge routers and a label indicating a cut-through path connecting them is referred to. A cut-through route label specifying means for specifying a cut-through route label indicating a cut-through route for transferring the attached user packet from the originating label edge router to the called label edge router without passing through the route server;
As information for setting a cut-through path from the originating label edge router to the destination label edge router, a cut including the cut-through path label and a destination address of a user packet included in the labeled user packet A route server comprising cut-through data notifying means for notifying through data to the originating label edge router. In the route server according to claim 5,
Further comprising a passing packet counting means for counting the number of user packets transferred by changing the label for each set of the destination address of the user packet and the cut-through label;
The cut-through data notifying means notifies the cut-through data to the calling label edge router only when the number of received user packets with labels reaches a predetermined determination reference value. Root server. A plurality of label edge routers and route servers are connected in a network, and a label switch router that forwards the received labeled user packet through a forwarding path corresponding to the label, and a labeled user packet transferred from the label edge router. In this case, it is used in a label switching network consisting of a route server that forwards a label specifying the transfer route to the label edge router on the destination side by transferring the user packet, and transmitted from the terminal of the accommodating user network. A label edge router for transferring a user packet addressed to a desired terminal with a label for specifying the transfer route, deleting the label from the received user packet with a label, and transferring the packet to the user network terminal. And
Based on cut-through data including a cut-through route label and a destination address transmitted from the route server, a user packet to a terminal having the destination address is transmitted from the label edge router to a predetermined destination label edge router. A cut-through route updating means for setting a cut-through route for transferring without passing through a route server;
And a packet transfer means for adding a cut-through route label indicating a cut-through route corresponding to the destination address of the terminal to the user packet when transmitting the user packet to a desired terminal. Label edge router to be. The label edge router according to claim 7,
Purge data including the cut-through path label added to the received labeled user packet and the destination address of the user packet included in the labeled user packet is notified to the originating label edge router of the labeled user packet. Purge data notification means for
The cut-through path update means deletes the setting of the cut-through path to the destination label edge router based on the cut-through path label and the destination address included in the received purge data. Router. The label edge router according to claim 8,
The purge data notifying means sends the purge data to the originating side when a desired terminal that is a destination of the user packet included in the received labeled user packet is not connected to a user network accommodated in the label edge router. A label edge router characterized by notifying a label edge router.

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