JP2003244198A - Packet forwarding apparatus, packet transmitting apparatus, packet forwarding system, and network failure recovery method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet forwarding apparatus, a packet transmitting apparatus, a packet forwarding system, and a network failure recovery method, which are reliable and reduce a time required for switchover by decreasing a time up to switchover start when failure switchover is conducted at a network layer during failure occurrence, in a packet forwarding system configured with a transmitting apparatus and a packet forwarding apparatus. <P>SOLUTION: When transmitting apparatus 41-45 detect that physical layer switchover cannot be done, this information is notified to packet forwarding apparatus 31-36 as a switchover state information. Upon receipt of the information, the packet forwarding apparatus 31-36 conduct network layer switchover immediately. According to this arrangement, a time required for switchover can be reduced. By exchanging the switchover state information between the transmitting apparatus 41-45 and the packet forwarding apparatus 31-36, physical layer switchover and network layer switchover can be controlled in an interlocked fashion. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet transfer system including a plurality of transmission devices and a packet transfer device, which realizes high speed recovery in the event of a failure and improves system reliability. apparatus,
The present invention relates to a transmission device, a packet transfer system, and a network failure recovery method.

[0002]

2. Description of the Related Art Conventionally, packet communication using a network typified by the Internet has rapidly spread. The packet transfer system that constitutes this network is composed of, for example, a transmission device that constitutes a transmission network that performs data transfer in the physical layer, and a packet transfer device that is connected to the transmission device via a transmission path.

The packet transfer device in the above packet transfer system includes a physical layer terminating interface (hereinafter,
The interface is called an IF) unit, a storage unit that stores a packet transfer table, and a packet transfer processing unit.

The physical layer termination IF unit accommodates a transmission line connected to a transmission device to terminate the physical layer, transmits / receives a packet to / from the transmission device, and receives a packet from the transmission device into a packet transfer processing unit. And the packet received from the packet transfer processing unit to the transmission device.

The packet transfer table is composed of entries in which the header information of the packet and the information indicating the physical layer terminating IF section which should output the packet having the header information are associated with each other.

[0006] The packet transfer processing unit uses the physical layer termination I
For the packet received from the F section, the physical layer termination IF section to be output is determined and transmitted according to the header information by referring to the packet transfer table.

The transmission device is composed of a physical layer relay IF unit and a switch.

The physical layer relay IF unit accommodates a transmission line connected to the packet transfer device, transmits / receives the packet to / from the packet transfer device, and receives the packet received from the packet transfer device to the switch as a physical layer frame. The packet is transmitted and the packet received from the switch is transmitted to the packet transfer device.

The switch transmits the physical layer frame received from the physical layer relay IF section to a predetermined physical layer relay IF.
Send to department.

The transmission device has a physical path switching function as a function of failure switching in the physical layer, and when a failure occurs in the physical path, the traffic is transferred to another normal physical path.

The packet transfer apparatus has a network path switching function as a function of failure switching in the network layer, and sets a plurality of network paths. Forwards the traffic that was being forwarded to the rest of the normal network path.

In the packet transfer system composed of the above-mentioned transmission device and packet transfer device, when a failure occurs, physical layer failure switching and network layer failure switching are combined to perform failure recovery. That is, when a failure occurs, switching is first performed in the physical layer. Next, when the switching at the physical layer cannot be performed due to lack of spare resources, switching at the network layer is performed.

Further, the transmission network has a function of transmitting a failure notification alarm from the transmission device to a packet transfer device which is a device that terminates the transmission line when a failure occurs in the transmission network. Thus, the packet transfer device can detect a failure by receiving the failure notification alarm from the transmission network.

[0014]

However, it is necessary to control the order of switching processes so that the network layer switching operates after the physical layer switching. For this reason, when performing network layer switching, it is necessary to allow sufficient time until switching is started after detecting a failure and confirm that switching at the physical layer is inoperable. If a sufficient time is not taken until the switching of the network layer is started, the failure switching of the physical layer may operate after the switching of the network layer. When the physical layer failure is switched after the network layer is switched in this way, the network route whose failure has been recovered by the network layer switching is changed again by the physical layer switching, and the state of the network route becomes unstable. turn into.

Therefore, the above-mentioned conventional packet transfer system has a problem that it takes a long time to start the switching when the network layer is switched, and the switching time required from the occurrence of a failure to the completion of the switching is long.

In view of the above problems, an object of the present invention is to shorten the time required for switching by reducing the time until switching is started when switching the network layer, and to provide a highly reliable packet transfer apparatus and transmission apparatus. , To provide a packet transfer system.

[0017]

In order to achieve the above object, a packet transfer apparatus according to the present invention comprises a plurality of transmission apparatuses which form a transmission network for transferring data in a physical layer, and the transmission apparatus by a transmission line. A packet transfer device in a packet transfer system comprising a plurality of packet transfer devices connected to each other, wherein the physical layer is terminated by accommodating a transmission path connected to the transmission device, and a packet is transmitted between the transmission device and the packet. And the switching state information is transmitted and received, the packet received from the transmission device is transmitted to the packet transfer processing unit, the switching state information is transmitted to the switching state information processing unit, and the packet received from the packet transfer processing unit is transmitted. The physical layer termination interface unit to be transmitted to the device, the header information of the packet, and the physical information to output the packet having the header information. A storage unit that stores a packet transfer table in which information indicating an ear termination interface unit is associated, and a packet is received from the physical layer termination interface unit and the packet transfer table is referred to thereby to receive the packet. From the physical layer termination interface unit, which determines the physical layer termination interface unit to be output according to the header information of the packet, and which transmits the received packet to the determined physical layer termination interface unit. And a switching state information processing unit that receives the switching state information and rewrites the packet transfer table based on the received switching state information.

The packet transfer apparatus of the present invention is that the physical layer terminating IF section transmits / receives switching state information to / from the transmission apparatus, and that the switching state information processing section is provided. Different from the transfer device.

According to such a packet transfer device of the present invention, switching state information can be transmitted and received to and from the transmission device, and switching at the network layer can be controlled using the switching state information. . Therefore, by exchanging appropriate switching state information with the transmission device, it is possible to shorten the time from the occurrence of a failure to the start of network layer switching.

In order to achieve the above-mentioned object, the transmission apparatus of the present invention comprises a plurality of transmission apparatuses which form a transmission network for transferring data in a physical layer, and a plurality of transmission apparatuses which are connected to the transmission apparatuses by transmission lines. A packet transfer device in a packet transfer system, the transmission device being connected to the packet transfer device, transmitting and receiving packets and switching state information to and from the packet transfer device, The packet received from the transfer device is transmitted to the switch as it is in the physical layer frame, the packet received from the switch is transmitted to the packet transfer device, and the switching state information received from the switching state information processing unit is transmitted to the packet transfer device. The physical layer relay interface unit to be transmitted and the physical layer received from the physical layer relay interface unit. The switch for transmitting a frame to a predetermined physical layer relay interface unit, and whether or not the failure switching in the transmission network is performed when a failure occurs and whether the failure switching is possible or not are confirmed, and the failure switching is not performed. Alternatively, when the failure switching is impossible, the switching status information processing unit for transmitting switching status information to that effect to the physical layer relay interface unit is provided.

The transmission apparatus of the present invention is that the physical layer relay IF section transmits / receives the switching state information to / from the packet transfer apparatus and that the transmission state information processing section is provided. Different from

According to such a transmission device of the present invention, it is possible to confirm the implementation state of the physical layer switching and to transmit / receive it as the switching state information to / from the packet transfer device. Therefore, the packet transfer device can appropriately control the network layer switching according to the switching state information, and can shorten the time from the occurrence of a failure to the start of the network layer switching.

Further, in order to achieve the above-mentioned object, the packet transfer system of the present invention comprises a plurality of transmission devices forming a transmission network for performing data transfer in the physical layer, and a transmission line connected to the transmission devices. In a packet transfer system including a plurality of packet transfer devices, a transmission device that detects a failure switching state in a physical layer and sends switching state information indicating the detected failure switching state to the packet transfer device, and the transmission device. A packet transfer device that receives the switching state information and controls failure switching in the network layer based on the received switching state information.

According to the packet transfer system of the present invention as described above, the failure transfer state information in the physical layer is shared as the switching state information between the packet transfer device and the transmission device, and the switching in the physical layer and the network layer are performed. The switching in can be coordinated. Therefore, it is possible to shorten the time from the occurrence of a failure to the start of network layer switching.

Further, in order to achieve the above object, the network failure recovery method of the present invention is such that a plurality of transmission devices constituting a transmission network for transferring data in a physical layer are connected to the transmission device by a transmission path. A network failure recovery method in a packet transfer system comprising a plurality of packet transfer apparatuses, wherein the transmission apparatus does not perform failure switching in a physical layer in the transmission network when a failure occurs in the transmission network. At this time, switching state information indicating that failure switching is not performed in the physical layer is transmitted to the packet transfer apparatus, and the packet transfer apparatus that has received the switching state information performs failure switching in the network layer. It is characterized by

According to the network failure recovery method of the present invention as described above, the packet transfer apparatus can detect that the failure switching in the transmission network is not performed, so that the switching is performed in the network layer immediately after the detection. be able to. Therefore, it is possible to shorten the time from the occurrence of a failure to the start of network layer switching.

Further, the network failure recovery method of the present invention allows the physical layer to detect when a failure occurs in the transmission network and the transmission device detects that the failure switching cannot be performed within a predetermined time. The switching state information indicating that the failure switching of (1) cannot be performed within a predetermined time is transmitted from the transmission device to the packet transfer device.

As a result, after the occurrence of a failure in the transmission network, a packet indicating that the failure switching in the physical layer cannot be performed within a predetermined time is made in a short time equal to or less than the time required for the failure switching in the physical layer. It can be detected by the transfer device. Therefore, it is possible to shorten the time from the occurrence of a failure to the start of network layer switching.

Further, the network failure recovery method of the present invention is carried out if failure switching in the physical layer can be performed within a predetermined time when a failure occurs in the transmission network, and failure switching in the physical layer is performed at a predetermined time. When it is possible to carry out over the above range, information on whether to carry out or not is transmitted from the transmission device to the packet transfer device as switching state information.

As a result, it is possible to flexibly carry out the failure switching according to the time required for the physical layer switching which is possible when the failure occurs.

[0031]

DETAILED DESCRIPTION OF THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration example of a packet transfer system according to an embodiment of the present invention. In the figure,
Reference numeral 1 denotes a packet transfer system, which is a packet transfer device 31 connected to transmission devices 41 to 45 forming a transmission network 2 for performing data transfer in a physical layer and predetermined transmission devices 41 to 45 via a transmission path. ~ 36 are included.

In the transmission network 2, the transmission device 43 is connected to the transmission devices 41, 42, 44, 45 and the packet transfer device 34.

In addition, the packet transfer device 31 uses the transmission line 6
It is connected to the user networks 11 and 12 via 1, 62 and to the transmission device 41 via the transmission path 51.

The packet transfer device 32 includes transmission lines 63, 6
4 and the user networks 13 and 14 and the transmission device 42 via the transmission path 52.

The packet transfer device 33 is connected to the transmission device 41 via the transmission line 53, and the packet transfer device 34 is connected to the transmission device 43 via the transmission line 54.

The packet transfer device 35 includes transmission lines 65, 6
It is connected to the user networks 15 and 16 via 6 and to the transmission device 44 via the transmission path 55.

The packet transfer device 36 includes transmission lines 67, 6
8 is connected to the user networks 17 and 18 via 8 and is connected to the transmission device 45 via the transmission path 56.

A wavelength division multiplexing optical cross connect can be used as the transmission devices 41 to 45, and an IP router can be used as the packet transfer devices 31 to 36. In this case, WDM can be used as the physical layer and IP can be used as the network layer.

The packet transfer devices 31 to 36 accommodate the user networks 11 to 18 and the transmission device 41.
~ 45 to receive switching status information, and control failure switching at the network layer based on this switching status information.

The transmission devices 41 to 45 detect the failure switching state in the physical layer and transmit the switching state information to the packet transfer devices 31 to 36.

According to the packet transfer system 1 as described above, the packet transfer devices 31 to 36 and the transmission devices 41 to 45.
It is possible to share the information on the failure switching state in the physical layer as the switching state information, and link the switching in the physical layer and the switching in the network layer. For this reason,
It is possible to shorten the time from the occurrence of a failure to the start of network layer switching.

FIG. 2 is a diagram showing a configuration example of the packet transfer devices 31 to 36. In FIG. 2, the configuration of the packet transfer device 31 and its connection state are illustrated as an example, but the configuration of the packet transfer device itself is not limited to the contents of the packet transfer table 111, but all the packet transfer devices 31 to 31.
Same at 36.

The packet transfer device 31 includes a storage unit 117 that stores a packet transfer table 111, a switching state information processing unit 112, a packet transfer processing unit 113, and a physical layer termination IF.
It is composed of parts 114 to 116.

The packet transfer table 111 is composed of entries in which the header information of the packet and the information designating the physical layer termination IF sections 114 to 116 to which the packet having the header information should be output are associated with each other.

The switching state information processing unit 112 receives the switching state information from the physical layer terminating IF unit 114, and rewrites the packet transfer table 111 based on the received switching state information.

The packet transfer processing unit 113 receives a packet from the physical layer terminating IF units 114 to 116, refers to the packet transfer table 111, and outputs the physical layer to be output according to the header information of the received packet. The terminal IF units 114 to 116 are determined and the received packet is transmitted.

The physical layer termination IF section 114 is used by the transmission device 4
1, the physical layer is terminated by accommodating the transmission path 51 connected to 1, the packet and the switching state information are transmitted / received to / from the transmission device 41, and the packet received from the transmission device 41 is transmitted to the packet transfer processing unit 113. At the same time, the switching state information is transmitted to the switching state information processing unit 112, and the packet received from the packet transfer processing unit 113 is transmitted to the transmission device 41.

The physical layer terminating IF units 115 and 116 are transmission lines 61 and 62 connected to the user networks 11 and 12, respectively.
User network 1
Packets are transmitted to and received from the user networks 11 and 12, and packets received from the user networks 11 and 12 are transmitted to the packet transfer processing unit 113, and packets received from the packet transfer processing unit 113 are transmitted to the user networks 11 and 12. .

FIG. 3 is a diagram showing a configuration example of the transmission devices 41 to 45. Although the configuration of the transmission device 41 and its connection state are illustrated as an example in FIG. 3, the configuration of the transmission device itself is the same for all the transmission devices 41 to 46.

The transmission device 41 includes a switching state information processing unit 211.
And a switch 212 and physical layer relay IF units 213 to 215.

The switching state information processing unit 211 confirms whether or not the failure switching is performed within the transmission network 2 when a failure occurs, and also confirms whether or not the failure switching is possible, and when the failure switching is not performed. Alternatively, when failure switching is impossible, switching status information indicating that fact is transmitted to the physical layer relay IF unit 213.

The switch 212 is a physical layer relay IF unit 213.
The physical layer frames received from ˜215 to 215 are transmitted to predetermined physical layer relay IF sections 213 to 215.

The physical layer relay IF units 213 and 214 are the transmission lines 5 connected to the packet transfer devices 31 and 33, respectively.
1, 53 are accommodated, packets and switching state information are transmitted / received to / from the packet transfer devices 31, 33 via the transmission paths 51, 53, and the packets received from the packet transfer devices 31, 33 remain as physical layer frames. At the same time as transmitting to the switch 212, the packet received from the switch 212 is transmitted to the packet transfer devices 31 and 33, and the switching state information processing unit
The packet transfer device 3 receives the switching state information received from the 211.
Send to 1, 33.

The physical layer relay IF unit 215 is used by the transmission device 4
3 accommodates the transmission path connected to 3 and transmits / receives a packet to / from the transmission device 43, transmits the packet received from the transmission device 43 to the switch 212 as a physical layer frame, and transmits the packet received from the switch 212. The switching state information transmitted to the transmission device 43 and received from the switching state information processing unit 211 is transmitted to the transmission device 43.

Next, an example of the network failure recovery method in the packet transfer system 1 described above will be described with reference to the flow charts shown in FIGS. Incidentally, FIG.
Is a flowchart for explaining a failure recovery process of the transmission devices 41 to 45 when a failure occurs, and FIG. 5 is a flowchart for explaining a failure recovery process of the packet transfer devices 31 to 36 when a failure occurs. The network failure recovery method described here is one specific example of a method for performing failure recovery using the packet transfer system 1 including the packet transfer devices 31 to 36 and the transmission devices 41 to 45 described above.

Upon detecting the occurrence of a failure, the transmission devices 41 to 45 determine whether or not the failure switching in the physical layer can be performed within a predetermined time (SA1), and the failure switching in the physical layer is performed for a predetermined time. If it can be implemented within the time, the failure switching in the physical layer is executed (SA2).

Further, as a result of the determination in S1, if the failure switching in the physical layer cannot be performed within the predetermined time, is it possible to perform the failure switching in the physical layer beyond the predetermined time. It is determined whether or not (SA3).

If the result of this determination is that the failure switching can be implemented in the physical layer beyond the predetermined time, information on whether or not to implement the failure switching is transmitted to the packet transfer devices 31 to 36 as switching state information ( SA4).

If the failure switching in the physical layer cannot be performed within a predetermined time, or if the failure switching in the physical layer is not performed after the predetermined time, the switching status information to that effect is displayed. The packet is transmitted to the packet transfer devices 31 to 36 (SA5).

On the other hand, the packet transfer devices 31 to 36 receive switching state information regarding a failure that has occurred in the transmission network 2 from the transmission devices 41 to 45 (SB1), and the physical layer switching cannot be performed within a predetermined time. Is detected (S
B2).

Next, the packet transfer devices 31 to 36 are
Packet forwarding table based on received switching status information
111 is rewritten (SB3), and failure switching is performed in the network layer according to this packet transfer table 111 (SB4).

The embodiment described above is a specific example of the present invention, and the present invention is not limited to the above embodiment.

[0064]

As described above, according to the packet transfer device, the transmission device, the packet transfer system and the network failure recovery method of the present invention, when failure switching in the physical layer cannot be performed within a predetermined time, The transmission device detects it and sends that information as switching state information from the transmission device to the packet transfer device, and the packet transfer device that receives the switching state information immediately performs failure switching in the network layer without waiting time. It can be carried out.
As a result, in the conventional technique, it is necessary to allow a sufficient time until the switching is started after detecting the failure when the network layer is switched, but this time can be omitted, so that the switching required time can be shortened. it can. Therefore, a highly reliable packet transfer system can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a packet transfer system of the present invention.

FIG. 2 is a diagram showing a configuration example of a packet transfer device of the present invention.

FIG. 3 is a diagram showing a configuration example of a transmission device of the present invention.

FIG. 4 is a flowchart illustrating a network failure recovery process in the transmission device of the present invention.

FIG. 5 is a flowchart illustrating a network failure recovery process in the packet transfer device of the present invention.

[Explanation of symbols]

1 ... Packet transfer system, 2 ... Transmission network, 11-14,
21-24 ... User network 31-36 ... Packet transfer device, 41-45 ... Transmission device, 111 ... Packet transfer table, 112 ... Switching state information processing unit, 113 ... Packet transfer processing unit, 114-116 ... Physical layer termination IF section, 117 ...
Storage unit, 211 ... Switching state information processing unit, 212 ... Switch, 21
3 to 215 ... Physical layer relay IF unit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Junichi Murayama             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F-term (reference) 5K030 GA12 HA08 HD03 MA04                 5K033 AA06 CA17 CC02 EB06

Claims (6)

[Claims] 1. A packet transfer device in a packet transfer system, comprising: a plurality of transmission devices that form a transmission network that transfers data at a physical layer; and a plurality of packet transfer devices that are connected to the transmission devices by transmission lines. A transmission line connected to the transmission device, terminating the physical layer, transmitting and receiving a packet and switching state information to and from the transmission device, and transmitting a packet received from the transmission device to a packet transfer processing unit. A physical layer termination interface unit for transmitting the switching state information to the switching state information processing unit and transmitting the packet received from the packet transfer processing unit to the transmission device, header information of the packet, and the header information. Packet associated with the information that indicates the physical layer termination interface unit that should output the packet A storage unit that stores a table, and a physical layer termination interface unit that receives a packet from the physical layer termination interface unit and outputs the packet according to the header information of the received packet by referring to the packet transfer table. And the packet transfer processing unit that transmits the received packet to the determined physical layer termination interface unit, and receives switching state information from the physical layer termination interface unit, and based on the received switching state information. And a switching state information processing unit for rewriting the packet transfer table. 2. A transmission device in a packet transfer system, comprising: a plurality of transmission devices that form a transmission network that performs data transfer in the physical layer; and a plurality of packet transfer devices that are connected to the transmission devices by transmission paths. The packet transfer device is accommodated in a transmission path connected to the packet transfer device, the packet and the switching state information are transmitted to and received from the packet transfer device, and the packet received from the packet transfer device is sent to the switch as a physical layer frame. A physical layer relay interface unit for transmitting the packet received from the switch to the packet transfer device and transmitting the switching state information received from the switching state information processing unit to the packet transfer device; and the physical layer relay interface unit. Physical layer frame received from the specified physical layer relay interface unit Check the switch to be communicated, whether or not the failure switching is performed in the transmission network when a failure occurs, and whether the failure switching is possible or not possible.If failure switching is not performed or failure switching is not possible, A transmission device, comprising: the switching state information processing unit that transmits switching state information to that effect to the physical layer relay interface unit. 3. A packet transfer system comprising a plurality of transmission devices forming a transmission network for performing data transfer at the physical layer, and a plurality of packet transfer devices connected to the transmission device by a transmission path, wherein: Of the failure switching state, and transmitting the switching state information indicating the detected failure switching state to the packet transfer apparatus; and receiving the switching state information from the transmission apparatus, based on the received switching state information. And a packet transfer device for controlling failure switching in the network layer. 4. A network failure recovery method in a packet transfer system, comprising: a plurality of transmission devices that form a transmission network that transfers data at a physical layer; and a plurality of packet transfer devices that are connected to the transmission devices by transmission lines. In the transmission device, when a failure occurs in the transmission network, when the failure switching is not performed in the physical layer in the transmission network, the switching device indicates that the failure switching is not performed in the physical layer. A network failure recovery method, wherein status information is transmitted to the packet transfer apparatus, and the packet transfer apparatus that has received the switching status information performs failure switching at the network layer. 5. When the transmission device detects that a failure switching in the physical layer cannot be performed within a predetermined time when a failure occurs in the transmission network, the failure switching in the physical layer takes a predetermined time. The network failure recovery method according to claim 4, wherein switching state information indicating that the packet cannot be implemented is transmitted to the packet transfer device. 6. When failure switching in the physical layer can be performed within a predetermined time when a failure occurs in the transmission network, and failure switching in the physical layer can be performed beyond a predetermined time. 6. The network failure recovery method according to claim 5, wherein the information indicating whether to execute is transmitted as switching state information from the transmission device to the packet transfer device.