JPH03230643A - Routing system in packet exchange network - Google Patents

Abstract

PURPOSE:To bypass a call simply without interrupting the communication even when a fault takes place in a relay line by providing a bypass table to each packet exchange and revising path information in a packet according to the bypass table when a fault takes place in a call during communication passing through a relay line. CONSTITUTION:Each of packet exchanges 1a-1d is provided with a bypass table (6a-6d) representing the correspondence between a current path number and a bypass number to be replaced therewith. When a fault takes place in relay lines 2a-2e designated by path information of packets 5a, 5b to be relayed, the current path number of a packet is replaced with a bypass number obtained by referencing the bypass table (6a-6d) and routing is implemented based on the path number. Thus, communication is not interrupted even in the occurrence of a relay line fault during communication and the call is simply bypassed.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a packet switching network in which a packet transmission route is fixed for each call, each packet has its route information, and routing is performed based on the route information. This relates to a routing method.

[Conventional technology]

FIG. 4 is a block diagram showing a routing system in a conventional packet switching network, as disclosed in, for example, Japanese Patent Laid-Open No. 62-59443. In the figure, 1a to 1d are packet switches, and 28 to 2e are packet switches 13.
This is a relay line that connects 1d to 1d. 3a-3
d is a terminal device accommodated in any of the packet switches, for example, packet switches 1a and 1d, and 48
-4d are subscriber lines for accommodating each of the terminal devices 3a-3d in the packet switch 1a or 1d. Here, each of the packet exchanges 1a to 1d independently sets "0" and "1" to the trunk lines 2a to 2e and subscriber lines 4a to 4d connected thereto.

A route number of ... is assigned.

5a is a packet sent from the terminal device 3a to 3d, 5b
is a packet sent from the terminal device 3d to 3a, and FIG. 3 shows the format of the packets 5a and 5b. In the figure, 10 is the flag +m indicating the start and end of the packet, 11 is the link address (4), and 12 is the control field command (C) for link control.
13 is a frame check sequence (Fe2) for error checking. Further, 14 is data to be transmitted, and 15 is route information for the packet 5a.
.

5b is a transmission header in which the route numbers of the relayed packet switches 1a to 1d are arranged in the order of the relayed packet switches 1a to 1d. In FIG. 4, only this data 14 and transmission header 15 are shown as buckets 5a and 5b.

Next, the operation will be explained. When a call is made from the terminal device 3a to 3dK, when the call is set up, buckets) 5a, 5
The transmission path of b is determined. Now, as the transmission route,
For example, assume that a route is determined: terminal device 3a→subscriber line 4a→packet switch 1a→relay line 2b→packet switch 1d→subscriber line 4d→terminal device 3d.

Therefore, the terminal device 3a adds the transmission header 15 of the packet 5a to the relay line 2b in the packet switch 1a.
and the route number "0" of the subscriber line 4d in the packet exchange 1d are written as route information, and the bucket) 5a is sent to the subscriber line 4a.

The packet switch 1a that receives this bucket) 5a from the subscriber line 4a performs routing based on the route number "3" written at the beginning of the transmission header 15, and transmits the bucket to the corresponding trunk line 2b. )5a is sent. In this case, the leading route number "3" in the route information used for the routing is removed from the transmission header 15. The packet switch 1d that received this packet 5a from the relay line 2b performed routing based on the route number "O" written at the beginning of the transmission header 15, and removed the route number "0". The packet 5a is sent to the corresponding subscriber line 4d. According to this bucket) 5a,
Data from the terminal device 3a is transmitted to the terminal device 3d.

Similarly, the packet 5b returned from the terminal device 3d to the terminal device 3a has route numbers "2" and "1" written in its transmission header 15, and is sent to the subscriber line 4d. Packet switches 1d and 1a each have
Routing is performed based on the route number ``2'' or ``1'' in the transmission header 15, and the route number used for routing is removed from the transmission header.By this packet 5b, the terminal device 3a is sent to the terminal device 3d. Data from is transmitted.

[Problem to be solved by the invention]

The routing system in conventional packet switching networks is configured as described above, so that even if a failure occurs in the trunk lines 28 to 2e, the packets 5a and 5b can be bypassed by simply determining the packet transmission route at the time of call setup. No routing is performed, and after the call is set up, the relay lines 2a to 2e containing the call are
If a failure occurs, it is necessary to restart the call setup in order to continue the communication, and during that time the communication is interrupted.
The problem was that the interruption time was also long.

This invention was made to solve the above-mentioned problems. Even if a relay line failure occurs during communication, communication will not be interrupted, the procedure is simple, and the processing load on the packet switch does not increase. The purpose of this invention is to obtain a routing method in a packet switching network that allows calls to be detoured.

[Means to solve the problem]

The routing method in the packet switching network according to the present invention is such that each packet switch has a detour table showing the correspondence between the current route number and the detour route number to be replaced,
If there is a failure in the relay line specified by the route information of the packet to be relayed, the current route number of the packet is replaced with the detour route number obtained by referring to the detour table, and the current route number of the packet is changed based on the route number. It performs routing.

[For production]

The packet switch in this invention performs routing based on the route information of the packet to be relayed, and when a failure occurs in the relay line, it refers to the detour table based on the strategy number of the failed relay line and provides the corresponding detour route number. At the same time, if the route information of the packet to be relayed specifies the route number of the failed relay line, the current route number is replaced with the selected detour route number and routing is performed. To realize a routing method in a packet switching network that allows calls to be detoured without interrupting communications even if a relay line failure occurs during the network (without increasing the processing load on the packet switching equipment). .

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 1a to 1d are packet switches, 28 to 2e
3a to 3d are relay lines, 3a to 3d are terminal devices, 43 to 4d are subscriber lines, and 5a and 5b are packets having the format shown in FIG. Since the parts are the same or equivalent, detailed explanations will be omitted.

Further, 63 to 6d are detour tables provided in each of the packet switches 13 to 1d. This detour table 6
a to 6d, the route number assigned to each relay line 23 to 2e in each packet switch 13 to 1d is the current route number, and each of the current route numbers is assigned the relay line number. Each route number on a detour route to be detoured when a failure occurs in the lines 2a to 2e is associated as a detour route number.

FIG. 2 shows this detour table 6a provided in the packet switch 1a. Fig. 2 shows an example where the strategy number "3" of the trunk line 2b is used as the current route number, and the column for the detour route number shows the number 2 when a failure occurs in the trunk line 2b. The route numbers for each of the two detour routes are written. That is, on one side, the route number "2" of the relay line 2a in the Nokkerat exchange 1a and the route number "2" of the relay line 2d in the packet exchange 1b, which is a detour route of the relay line 2a → packet switch 1b → relay line 2d, are shown. Number “1”
” is written on the other side, and the relay line 2C is written on the other side.
→ Packet switch 1C → Detour route of trunk line 2e,
"Route number of trunk line 2C in packet switch 1a"
4'' and the route number "1" of the trunk line 2e in the packet switch 1C are written.

Next, the operation will be explained. When a call is set up between the terminal devices 3a and 3d, during normal operation, a predetermined strategy number "3,0" is written in the transmission header 15 between the terminal devices 3a and 3d, as in the conventional case. Or “2,1
Packets 5a and 5b with "" are sent and received. If a failure occurs in the trunk line 2b, the packet switch 1a detects the failure and sends and receives the packets 5a and 5b based on the route number "3" of the trunk line 2b. Refer to the detour table 6a.

Then, one of the two detour route numbers associated with the current route number "3" is selected in consideration of priority order, traffic, etc., and a detour route is determined.

Here, if the detour route number "2,1" is selected, then when the packet switch 1a receives a packet whose first route number in the route information of the transmission header 15 is "3",
After replacing the route number '3' with '2.1' extracted from the detour table 6a, the routing is performed.

Therefore, the bucket) 5a from the terminal device 3a is sent to the trunk line 2a according to the leading route number "2".At this time, as in the conventional case, the strategy number used for the routing in the route information is "2'" is removed, and the route number of the transmission header 15 becomes "1.0" as shown in the figure.

The packet switch 1b performs routing of the bucket 5a based on the leading route number "1" in the transmission header 15, and sends the packet 5a with the strategy number "1" removed to the packet switch 1d.

Therefore, the packet switch 1dVc becomes K when the bucket 5a, which has the same route information as before the detour, arrives.
The packet switch 1d executes routing according to the route information and sends the packet 5a to the terminal device 3dK. With this packet 5a, data from the terminal device 3a is
The data is transmitted to the terminal device 3d without being interrupted due to a failure in the relay line 2b.

Similarly, when the packet switch 1d detects a failure in the trunk line 2b, it refers to the detour table 6d based on the route number "2" of the trunk line 2b and determines, for example, the detour route number "'1.0". Select the detour route '''. After that, when this packet switch 1d receives a packet whose initial route number is 2'',
, 0'' and performs routing, and sends the bucket) 5b from the terminal device 3d to the relay line 2d. Routing is then performed using the corresponding route number in the packet exchangers 1b and 1a, and the packet of this relay line 2b is Data from the terminal device 3d is transmitted to the terminal device 3a without being interrupted by a failure.

〔Effect of the invention〕

As described above, according to the present invention, a detour table is provided in each packet switch, and when a failure occurs in a relay line that includes a call in progress, the route information in the packet is replaced according to the detour table. With this configuration, even if a failure occurs in the relay line, the call can be detoured without interrupting the communication or increasing the processing load on the packet switching equipment. Since the same algorithm can be used to process failures in relay lines, it is possible to obtain a routing system in a packet-switched network that can easily deal with failures that occur at multiple locations within the packet-switched network.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a routing method in a packet switching network according to an embodiment of the present invention, FIG. 2 is an explanatory diagram showing its detour table, and FIG. FIG. 4 is a block diagram showing a routing method in a conventional packet switching network. 1a to 1d are packet switches, 23 to 2e are relay lines,
3a to 3d are terminal devices, 4a to 4d are subscriber lines, and 5a
, 5b is a packet, and 63 to 6d are detour tables. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] A plurality of packet switches are connected to each other via relay lines, and a terminal device is housed in each of the packet switches to form a packet switching network, and a transmission route for packets transmitted within the packet switching network is fixed for each call. In a routing method in a packet switching network in which the packets to be transmitted have their route information, and each of the packet switches that relays the packets performs routing based on the route information that the packets have, Each packet switch is provided with a detour table showing the correspondence between the current route number and the detour route number to be replaced with the current route number, and the packet switch detects that a failure has occurred in the trunk line. Then, the corresponding detour route number is selected by referring to the detour table based on the route number of the failed relay line, and the route information of the packet to be relayed specifies the route number of the failed relay line. A routing method in a packet switching network characterized in that, if the route information included in the packet has a current route number specifying the failed relay line, the current route number specifying the failed relay line is replaced with the selected detour route number.