JP2001024636A - Wide area network equipment - Google Patents

Abstract

(57) [Summary] An inter-LAN connecting device (20) and (21) connecting LANs (10) and (11), and WAN nodes (40) and (41) connecting the inter-LAN connecting devices (20) and (21) with a WAN (relay) line (60). In the wide area network device configured as described above, when a network failure or the like occurs, switching to the backup routes 71 and 72 is quickly, efficiently, and reliably performed. A line switching control unit (32, 52) of a LAN connection device (20) and a WAN node (40) jointly performs line switching to backup routes (71, 72). Preferably, both the line switching control units 32 and 52 execute the line switching based on a predetermined priority, or the bypass target path search table 36 and
Select a backup route based on 56. More preferably, based on a table specifying the priority of a path set up on the WAN line 60, the line is switched to a backup route of the path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wide area network device, and more particularly, to an inter-LAN connecting device for connecting LANs,
The present invention relates to a wide area network device including a WAN node connecting LAN-to-LAN connecting devices with a WAN line.

[0002] In recent network systems,
With the progress of client-server development, the need for wide-area (inter-remote) network devices connecting LAN-to-LAN connecting devices via wide-area WAN lines is rapidly increasing. Conventionally,
LAN systems developed mainly for transmission of information systems tend to be integrated with core business, and wide-area network devices connected to such LAN systems are required to have high reliability.

[0003]

2. Description of the Related Art FIG. 6 shows an example of a general wide area network device connecting a plurality of LANs. In a station A, a LAN 10 is connected to a WAN node 40 via a LAN connection device 20, In the office, the LAN 11 is connected to the WAN node 41 via the LAN connection device 21. And WAN node 40
WAN line (relay line) 60 between ATM and 41 (ATM megalink, etc.)
Connected by

[0004] The WAN nodes 40 and 41 are connected via a backup INS line 61.
The AN connecting devices 20 and 21 are connected via an INS line 62 for backup. Under normal conditions, LANs 10 and 11 are connected between LANs 20, WAN nodes 40, WAN lines 60, W
Communication is performed on the normal route 70 via the AN node 41 and the LAN connection device 21.

[0005] For example, when a failure occurs in the WAN node 41 (shown by ★), communication between the LANs 10 and 11 is performed by the LAN connection device 2.
0, the INS line 61, and the backup route 72 via the LAN connection device 21. When a failure occurs in the WAN line 60 (shown by ★), communication between the LANs 10 and 11
In addition to the backup route 72, the process is performed via the backup route 71 using the INS line 61 instead of the WAN line 60.

FIG. 7 shows a configuration example of the LAN connection device 20 and the WAN node 40 shown in FIG. LAN connection device 20
Is the LAN line section 31 connected to the LAN 10, the line switching control section 3
2. It comprises a WAN line unit 33 connected to the WAN node 40, an INS line unit 34 connected to the INS line 61, and a failure detection unit 35.

The WAN node 40 includes a terminal line unit 51 connected to the WAN line unit 33, a line switching control unit 52, a WAN line unit 53 connected to the trunk line 60, and an INS line unit 5 connected to the INS line 62.
4 and a failure detection unit 55. Normal, LAN10
The communication of LAN line section 31, line switching control section 32, WAN line section
33, terminal line section 51, line switching control section 52, WAN line section 53,
And via the normal route 70 via the trunk line 60.

[0008] The failure detection unit 55 detects the opposite station failure signal 73 and the network failure signal 74 via the WAN line unit 53, and directly detects the device failure signal 75 of the own station. Notify. The line switching control unit 52 performs a PNNI (Private N) operation to switch the failed normal route 70 to the backup route 71 via the INS line unit 54 and the INS line 62.
etwork-Network Interface).

[0009] Further, the failure detection unit 55 sends failure signals 73 to 75 to the failure detection unit 35 via the terminal line unit 51 and the WAN line unit 33.
give. The failure detection unit 35 notifies the line switching control unit 32 of these. The line switching control unit 32 performs an operation of switching the failed normal route 70 to the backup route 72 via the INS line unit 34 and the INS line 61 by using a RIP (Routing Informat
ion Protocol) and OSPF (Open Shortest Path First).

[0010]

As described above, in the conventional wide area network apparatus, the line switching control unit 52 and the line switching control unit 32 separately use the failure signals 73 to 75 as triggers to back up the backup routes 71 and 72. Since the operation is performed, the switching timing of the backup routes 71 and 72 is difficult.

For example, when the trunk line returns to normal after the backup of the line switching control unit 32 operates first, flapping occurs on the backup route 72 and the normal route 70. For this reason, the switching takes a long time of several tens of seconds to several minutes, and cannot meet the system requirement of several seconds. Also,
Problems such as inadvertent calls to the backup route may occur, resulting in reduced system performance and unnecessary INS.
Was incurring charges.

Accordingly, the present invention provides an inter-LAN connecting device for connecting LANs, and a WA for connecting the inter-LAN connecting devices via a WAN line.
It is an object of the present invention to quickly, efficiently, and reliably switch to a backup route when a network failure or the like occurs in a wide area network device including N nodes.

[0013]

According to a first aspect of the present invention, there is provided a wide area network apparatus comprising:
It is characterized in that the LAN connection device and the WAN node each have a line switching control unit connected so as to jointly switch lines to the backup route.

That is, the inter-LAN connecting device and the line switching control unit of the WAN node are connected by the communication line. By the notification via the communication line, the two-line switching control unit can perform the joint switching to the backup route. This allows quick switching to the backup route,
It can be implemented efficiently and reliably,
For example, flapping or the like during line switching does not occur.

Further, in the present invention according to claim 2,
The LAN connection device has a failure detection unit that detects a failure,
The line switching control unit of the LAN-to-LAN connecting apparatus determines which of the two line switching control units should execute line switching with priority when the failure detection unit detects a failure, in a predetermined priority order. Can be determined based on

That is, the fault detecting unit of the LAN-to-LAN connecting apparatus detects a network fault, a counter station fault, or a fault of the own station, and notifies the line switching control unit of the self station. The line switching control unit determines which of the two line switching control units performs the switching process based on a preset priority, and immediately executes the line switching in the case of the own station, and executes the other line switching. An instruction to suppress the switching operation is given to the switching control unit. Also, when the priority of the switching operation of the other line switching control unit is high, a notification is given to perform the switching process.

As a result, the switching to the backup route can be performed without fluttering based on the priority. Further, in the present invention according to claim 3, the WAN node has a failure detection unit that detects a failure,
The failure detection unit of the WAN node may notify the detected failure to the failure detection unit of the LAN connection device.

That is, the failure detection unit of the WAN node detects the failure and notifies the failure detection unit of the LAN connection device. The fault detecting unit notifies the fault to the line switching control unit of the LAN connection device. Subsequent operations are the same as in claim 2. This allows the line switching control unit of the LAN-to-LAN connecting device to execute switching to the backup route based on the priority, triggered by the failure detected by the failure detection unit of the WAN node.

In the present invention according to claim 4,
The WAN node has a failure detection unit for detecting a failure, and the WAN
When the failure detection unit detects a failure, the line switching control unit of the node determines which of the two line switching control units performs the line switching with priority based on a predetermined priority. It is possible to

That is, the failure detection section of the WAN node detects the failure and notifies the line switching control section of its own station of the failure. The line switching control unit performs the same operation between the two line switching control units as the line switching control unit of the LAN-to-LAN connecting apparatus according to claim 2 based on a preset priority.

Further, in the present invention according to claim 5,
The line switching control unit of the LAN connection device or the WAN node,
When the line switching performed by the own station cannot be performed, the line switching is notified to the other line switching controller, and the other line switching controller receiving the notification can execute the line switching.

That is, each of the line switching control units, when the line switching started by the instruction to switch to the backup route or the like cannot be performed, notifies the other line switching control unit to leave the line switching to another backup route. Do. Thus, when the line switching of the backup route with the higher priority cannot be performed, the line can be switched to the line switching of the backup route with the lower priority. If line switching of both backup routes cannot be performed, a line switching instruction can be given alternately until either one of the two backup routes can be switched.

In the present invention according to claim 6,
The line switching control unit of the LAN connection device or the WAN node,
It has a table that specifies the priority of the path that is set up on the WAN line, and it is possible to switch the line to the backup route of the path based on the priority.

That is, the line switching control unit of the LAN connection device or the WAN node refers to the table specifying the priority of the path to be set up on the WAN line, and switches the line of the higher priority path to the backup route. I do. As a result, it is possible to back up an important path with priority.

Further, in the present invention according to claim 7,
The line switching control unit of the LAN connection device or the WAN node,
If the line switching is not completed before a predetermined time elapses after the start of the line switching, a timer may be provided for use in determining that the line switching has not been performed.

That is, each line switching control unit starts a timer when line switching is started. If the timer times out before the line switching is completed, the line switching control unit determines that the line switching cannot be performed, and leaves the other line switching control unit to switch the line.

In this way, when the time required to complete the line switching is longer than a predetermined time due to a failure or a routing process, the line switching can be transferred to the other line switching control unit. Further, in the present invention according to claim 8, the line switching control unit of the LAN-to-LAN connecting device can have a bypass target path search table.

Further, in the present invention according to claim 9, the line switching control unit of the WAN node can have a bypass target path search table. That is, the LA
When a plurality of backup routes exist, the line switching control unit of the N-to-N connection device or the WAN node can select and switch the optimal backup route with reference to the bypass target path search table.

In the present invention according to claim 10,
The WAN node may be one of an ATM switch and a frame relay switch, and the two line switching control units may perform the joint operation by using PVC. Further, in the present invention according to claim 11, the failure detection unit of the WAN node transmits a notification of the failure to a CLLM.
It can be performed on either the message or the OAM cell.

[0030]

FIG. 1 shows an embodiment of a wide area network apparatus according to the present invention. This embodiment is different from the conventional example shown in FIG.
In some cases, the (shaded portion) jointly controls the switching to the backup route 71 or 72 with the signals 76 and 77 passing through the WAN line portion 33 and the terminal line portion 51.

The operation of the wide area network device shown in FIG. 1 will be described below with reference to the flowchart of FIG. In step S10 in the figure, the failure detection unit 55 detects the occurrence of a failure in the network (relay line), the opposite station, or its own station, and notifies the failure detection unit 35 of this. When the WAN node 40 is a frame relay switch and an ATM switch, this notification is sent to a CLLM (Consolidated Link Lay
er Management) message and the OAM cell.

The failure detecting section 35 gives a switching instruction to the line switching control section 32 (step S11 in the figure). The control unit 32 transfers the switching instruction as a line switching processing command (signal) 76 via the PVC extended to the line switching control unit 52 (S12). Control unit 5
2 transfers the line switching processing command to the INS line unit 54 (S
13). The INS line section 54 receives the line switching processing command and
A call is made to the S line 62 to execute a line switching process (S14), and if the switching process is successful, a processing result (OK) is transmitted to the control unit 52 (S15 and S16).

The control unit 52 transfers the received processing result (OK) to the control unit 32 (S17). The control unit 32 receives the processing result and ends the backup route change processing (S1
8). In step S15, if the line switching process has not been successful, the INS line unit 54 transmits a processing result (NG) to the control unit 52 (S19), and the control unit 52 transmits the processing result via PVC. The included signal 77 is transferred to the control unit 32 (S20).

The control unit 32 receives the processing result (NG), and
The calling / switching instruction is notified to the line unit 34 (S21). The INS line unit 34 executes the switching process to the INS line 61 (S22), and when the switching process is successful, notifies the control unit 32 of the processing result (OK) (S23 and S24). The control unit 32 ends the backup route change process (S25).

In step S23, if the line switching processing has not been successful, the INS line section 34 sends a processing result (NG) to the control section 32 (step S26). Thereafter, the process returns to step S12, and the same operation is repeated until the backup route (detour route) 71 or 72 is established. FIG. 3 shows the format of the CLLM message. The octet number indicates the number of each octet constituting the CLLM message, and the decimal number indicates a specified value in each octet in a decimal number.

The CLLM message has the octet number “1”.
And the address field of "2", the control field of octet number "3", the octet numbers "4" to "20"
+2 (n-1) "and a frame check sequence (FCS) field of octet numbers" 19 + 2n-1 "and" 20 + 2n-1 ". The XID information field includes a format identifier field and a group field, and the group field further includes a group identifier field, a group length field, and a group value field.

The group value field further includes a parameter set identification field, a reason indication identification field, and a DLCI identification field. The reason display identification field includes “reason identifier (= 2)”, “parameter length (= 1)”, and “reason display value”.

FIG. 4 shows the TCC standard J of the above “reason display value”.
An example of the definition in T-Q922 is shown, and the "reason display value"
“00000010”, “00000011”, “00000110”, “000001
11 "," 00001010 "," 00001011 "," 00010000 ", and" 00010001 ", respectively," light congestion notification "," heavy congestion notification "," unused "," fixed failure notification "," all frame discard notification ""," Unused "," Unused ", and" Unused "
Is supported.

In the present embodiment, "00000110" and "00000111" of the "reason display values" are used for fault notification. In the embodiment of FIG. 2, the failure detection unit 55 detects a failure,
This is notified to the failure detection unit 35, and the notification is used as a trigger to start the line switching process.
The line switching process may be started based on a failure detected by the own station without receiving a notification from 55.

FIG. 5 is a flowchart showing a modified operation example in the wide area network device. In this operation example, the failure detection unit 55 notifies the failure detection unit 35 of the occurrence of the failure signal 73, 74, or 75 via the terminal line unit 51 and the WAN line unit 33, and executes the operation shown in FIG. Unlike the example,
It is also notified directly to the line switching controller 52 (step S3 in FIG.
0).

The failure detecting unit 35 does not give a switching instruction to the control unit 32 (S31 in FIG. 4), and the failure detecting unit 55 directly gives a switching instruction to the control unit 52 (S32 in FIG. 4). The subsequent operations in steps S32 to S46 are performed in the same manner as steps S13 to S26 in the embodiment of FIG. 2, except that the control unit 52 selects the backup route 71 as the priority bypass route instead of the control unit 32 (see FIG. S32) is that the processing result is transmitted to the control unit 52 and the route change processing ends.

In the above embodiment and the modified embodiment,
Although the switching to the backup route 71 has been given priority, the flow may be created such that the switching to the backup route 72 is given priority. Further, a table in which the priorities of the line switching control units 32 and 52 can be set may be prepared, and the switching process may be performed with reference to this table.

Further, the switching processing operation was repeated until switching to one of the backup routes 71 and 72.
If the switching processing operation has been performed a predetermined number of times or more, the processing may be terminated assuming that there is no backup route.
Further, when there are a plurality of backup routes in the line switching control unit 32 or 52, detour target path search tables 36 and 56 (see FIG. 1) in which priority is set for these backup routes are prepared in each line switching control unit. The backup route may be selected with reference to this table.

In steps S19 and S26 of the embodiment and steps S37 and S45 of the modified embodiment, the line switching control units 32 and 52 check the processing results (NG) of the line switching from the INS line units 34 and 54, respectively. After receiving, the process proceeds to the next step. However, if the processing result is not received after a predetermined time has elapsed, the process may proceed to the next step.

Further, the line switching control unit 32 or 52 prepares a table designating the priority of the path to be set up on the trunk line (WAN line) 60, and switches the important path having the higher priority to the backup route. It may be performed. That is, it is possible to designate a path by a prefix or port number of the transmitting side and / or the receiving side, prepare a table in which priority is assigned to this path, and switch from the path with the higher priority to the backup route. it can.

[0046]

As described above, according to the wide area network apparatus of the present invention, the inter-LAN connecting apparatus and the line switching control unit of the WAN node jointly perform the line switching to the backup route. Therefore, when a network failure or the like occurs, switching to the backup route can be performed quickly, efficiently, and reliably.

Further, the line switching control unit of the LAN connection device or the WAN node executes line switching based on a predetermined priority or selects a backup route based on a bypass target path search table. With such a configuration, it is possible to select an optimal backup route.

Further, the line switching control unit of the LAN connection device or the WAN node performs the line switching to the backup route of the path based on the table specifying the priority of the path to be established on the WAN line. With this configuration, important paths can be backed up with priority.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a wide area network device according to the present invention.

FIG. 2 shows an operation example of the wide area network device according to the present invention.
FIG. 4 is a flowchart showing (1).

FIG. 3 is a diagram showing a format of a CLLM message transmitted and received between failure detection units in the wide area network device according to the present invention.

FIG. 4 is a diagram showing a reason display definition used in a CLLM message transmitted and received between the failure detection units in the wide area network device according to the present invention.

FIG. 5 is an operation example of a wide area network device according to the present invention;
FIG. 4 is a flowchart showing (2).

FIG. 6 is a block diagram showing a configuration example of a backup route using an INS line in a general wide area network device.

FIG. 7 is a block diagram showing a configuration example of a conventional wide area network device.

[Explanation of symbols]

 10, 11 LAN 20, 21 LAN connection unit 31 LAN line unit 32 Line switching control unit 33 WAN line unit 34 INS line unit 35 Failure detection unit 36 Detour target path search table 40, 41 WAN node 51 Terminal line unit 52 Line switching Control unit 53 WAN line unit 54 INS line unit 55 Failure detection unit 56 Detour target path search table 60 Relay line (WAN line, ATM megalink) 61,62 INS line 70 Normal route 71,72 Backup route 73 Opponent station failure signal 74 Network fault signal 75 Equipment fault signal 76, 77 signal In the figure, the same reference numerals indicate the same or corresponding parts.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme Court ゛ (Reference) H04L 29/14 (72) Inventor Kaoru Nagakura 4-1-1, Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Stock In-house F-term (reference) 5K014 AA01 AA04 CA06 EA00 FA01 HA00 5K030 GA12 HA01 HC01 HC14 JL07 KX23 MA01 MB01 MD02 5K033 AA06 BA15 CB08 DA01 DB19 EA04 EB06 5K035 AA03 BB01 CC03 DD01 FF02 HH07 JJ01 LL07 JJ01 LL01

Claims (11)

[Claims] 1. An inter-LAN connecting device for connecting LANs, and the LA
A wide area network device including a WAN node that connects N-to-N connection devices with a WAN line, wherein the LAN-to-LAN connection device and the WAN node are connected so as to jointly switch lines to a backup route. A wide area network device, comprising a line switching control unit. 2. The system according to claim 1, wherein the inter-LAN connecting device has a fault detecting unit for detecting a fault, wherein the line switching control unit of the inter-LAN connecting device detects when the fault detecting unit detects the fault. A wide area network device, which determines which of the two line switching control units performs line switching with priority based on a predetermined priority. 3. The failure detection unit according to claim 2, wherein the WAN node has a failure detection unit that detects a failure, and the failure detection unit of the WAN node notifies the failure detection unit of the LAN connection device of the detected failure. A wide area network device characterized by the following. 4. The system according to claim 1, wherein said WAN node has a failure detection unit for detecting a failure, and said line switching control unit of said WAN node performs both line switching control when said failure detection unit detects a failure. A wide area network device, which determines which of the units performs line switching with priority based on a predetermined priority. 5. The line switching control unit of the LAN connection device or the WAN node according to claim 2 or 4,
When the line switching performed by the own station cannot be performed, the line switching is notified to the other line switching controller, and the other line switching controller receiving the notification performs the line switching. Network device. 6. The system according to claim 1, wherein the inter-LAN connecting device or the line switching control unit of the WAN node comprises:
A wide area network device having a table designating a priority order of a path provided on the WAN line, and performing a line switch to a backup route of the path based on the priority order. 7. The line switching control unit of the LAN connection device or the WAN node according to claim 2 or 4,
A wide area network device comprising a timer for use in determining that the line switching has not been performed when the line switching has not been completed before a predetermined time has elapsed after the start of the line switching. 8. The wide area network device according to claim 2, wherein the line switching control unit of the inter-LAN connecting device has a bypass target path search table. 9. The wide area network device according to claim 4, wherein the line switching control unit of the WAN node has a bypass target path search table. 10. The wide area network device according to claim 1, wherein the WAN node is one of an ATM switch and a frame relay switch, and both line switching control units perform the joint operation by PVC. 11. The wide area network device according to claim 3, wherein the failure detection unit of the WAN node notifies the failure by using a CLLM message or an OAM cell.