JPH06315046A - Dynamic routing control method - Google Patents

Abstract

PURPOSE:To provide the dynamic routing method which can efficiently and safely operate dynamic routing and can be applied to a path routing operation as well. CONSTITUTION:Each exchange on a connection route adds transmission delay time concerning a line inside a selected route to a first field provided inside the user signal of a common line signal system. At an exchange 3 to execute the dynamic routing, when the sum of cumulative transmission delay time shown in the first field and the transmission delay time of a line 14, for example, inside the selected route is less than previously decided allowable transmission delay time, this line of this route is used. On the other hand, a second field to show the presence/absence of the echo canceler of the selected line is provided inside the user signal of the common line signal system and when the echo canceler is used, it is displayed in the second field. At an exchange to execute the dynamic routing, the use of the echo canceler is judged from the contents of the second field, and the previously decided allowable transmission delay time is used respectively corresponding to each case.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dynamic routing control method that enables efficient and safe operation of dynamic routing in consideration of communication quality, and an efficient method in consideration of communication quality.
And a dynamic routing control method applicable to a safe path routing control method.

[0002]

2. Description of the Related Art In a communication network such as a telephone, a detour relay system is usually adopted in order to operate the communication network efficiently.

In the conventional detour relay system, a fixed detour system in which routes are selected in a predetermined order has been used.

However, the fixed detour system cannot flexibly deal with traffic fluctuations, and there is a limit to the efficient operation of the communication network.

On the other hand, with the advent of electronic switching systems and common line signaling systems in recent years, advanced detour relay systems called dynamic routing systems have become possible, various dynamic routing systems have been proposed, and some of them have been proposed. It has already been commercialized in an actual communication network.

Regarding dynamic routing, for example, Matsumoto and Watanabe “Dynamic Routing-Recent Network Operation Technology Trends”, IEICE, Vol.69, No.2, pp.164.
-167, 1986 etc.

Generally, the route selection of dynamic routing is
If the direct route between the two originating and terminating exchanges is selected first and all the lines of the direct route are blocked, the optimal route will be selected from the routes in the predetermined detour candidate group according to the time zone and the state of the communication network. It will be selected and routed to that route.

Therefore, when the route is routed in the detour candidate group, the total line length between the originating and terminating exchanges is increased, and the transmission delay time is extended.

When the transmission delay time is extended, the call quality is deteriorated due to the echo caused by the 2-wire to 4-wire conversion and the delay itself. Therefore, an echo canceller is inserted or routing is performed so that the transmission delay time is allowed. Measures such as restrictions are necessary.

In the conventional dynamic routing, a detour candidate group is defined in advance so that the communication quality is within an allowable range, and routing is restricted within the candidate group.

On the other hand, in recent years, research has been actively conducted A
TM (Asynchronous Transfer Mode)
When digital signal processing is introduced into a communication network, the transmission delay time in the communication network increases. Therefore, it is necessary to control and operate the communication network considering the transmission delay time more than ever before.

In consideration of such a situation, in the conventional dynamic routing control method, since various transmission delay times are evaluated on the safe side to determine the detour candidate group, the detour candidate group is extremely limited, and the dynamic routing is performed. There is a fear that it will not be fully utilized.

For example, the transmission delay time to reach a switch which executes dynamic routing varies greatly depending on the route to the switch and the device inserted between them, but assuming the conventional dynamic routing method, the worst transmission delay time is assumed. It is necessary to evaluate and decide the detour candidate group.

Further, although the allowable transmission delay time is significantly different between the case where the echo canceller is inserted and the case where the echo canceller is not inserted on the connection route, in the conventional dynamic routing control method, the safe side where the echo canceller is not inserted is used. In this case, the detour candidate group is selected, so that the detour candidate group is extremely limited.

In addition, if the connection form does not include the 2-wire to 4-wire conversion, the allowable transmission delay time is longer than that of the connection form that includes the 2-wire to 4-wire conversion. In routing, it is unavoidable to decide the detour candidate group by evaluating the allowable transmission delay time in the case where the 2-wire to 4-wire conversion on the safe side is included.

On the contrary, in the conventional dynamic routing, if the transmission delay time of each factor is erroneously evaluated, there is a possibility that the dynamic routing which does not satisfy the specified communication quality may be performed.

As for the path which is a bundle of lines, the routing of the path is performed to switch the path in response to the failure of the transmission line or the short-term fluctuation of traffic. Also, the transmission delay time is important, and there was a problem similar to that of dynamic routing.

[0018]

As described above, in the conventional dynamic routing, since the detour candidate group has to be decided in advance by assuming the worst case transmission delay time, the application range of the detour candidate group is narrowed. There was a problem that the advantages of dynamic routing could not be fully utilized.

The present invention has been made in view of the above circumstances, and an object of the present invention is based on a more practical allowable transmission delay time and on the basis of a device inserted on a connection route. It enables the routing to be operated efficiently and safely.

There is a similar problem regarding the path routing, and it is possible to operate the path routing efficiently and safely with respect to the communication quality.

[0021]

In order to achieve the above-mentioned object, the present invention provides a dynamic routing control method in a communication network using dynamic routing, in which each exchange on the connection route transmits on a line in the selected route. In a switch that adds the delay time to the first field provided in the common line signaling user signal and executes dynamic routing, the accumulated transmission delay time shown in the first field and the line in the selected route are displayed. The line of the route is used when the sum of the transmission delay times is less than or equal to a predetermined allowable transmission delay time.

Also, a second field indicating whether or not the echo canceller is inserted in the line selected by the exchange on the connection route is provided in the user signal of the common line signaling system, and the exchange on the connection route operates the echo canceller. When it is used, it is displayed in the second field, and in the exchange which executes the dynamic routing, the use of the echo canceller on the connection route is judged from the contents of the second field, and the use of the echo canceller is dealt with respectively. The mode using the predetermined allowable transmission delay time is effective.

Further, it is effective to use a predetermined allowable transmission delay time according to the transmission capability.

Furthermore, it is effective to automatically update the transmission delay time for the line stored in the exchange when the transmission delay time for the line is changed.

Furthermore, a third field indicating the accumulated transmission delay time is provided in the control link between the transmission terminal stations,
The transmission terminal station forming the path adds the transmission delay time related to the transmission link to be used to the third field and relays it to the next transmission terminal station, and the transmission terminal station switching the path indicates in the third field. It is effective when applied to path routing control for routing to the transmission link when the sum of the accumulated transmission delay time and the transmission delay time for the switching transmission link is equal to or less than a predetermined allowable transmission delay time.

[0026]

According to the present invention, a field for displaying the cumulative transmission delay time on the connection route is provided in the common line signal system, etc., and the transmission delay time concerning the line selected by each exchange is cumulatively added to the field and transferred. The switch which performs the dynamic routing is configured to select a route to be detoured from the detour candidate group based on the accumulated transmission delay time and the allowable transmission delay time.

Further, the route of the detour candidate group is selected based on the display information indicating the use of the echo canceller indicating that the echo canceller has been inserted on the connection route and the call transfer capability.

Similar means are also applied to the path routing.

In the present invention, the dynamic routing is applied because the alternative route is selected from the alternative route group based on the transmission delay time, the inserted device, and the attribute of the call that actually reach the exchange that performs the dynamic routing. The range can be expanded as compared with the conventional method, and the dynamic routing can be effectively operated.

Further, since the transmission delay time or the like that is actually used is used, it is possible to operate the dynamic routing which is safe for the communication quality.

With respect to the path routing, it is possible to operate the path routing efficiently and safely with respect to the communication quality for the same reason.

[0032]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 shows a communication network for explaining an embodiment relating to the dynamic routing of the present invention.
4, 5, 6, 7, 8, 9 are exchanges, 11, 12, 13,
14, 15, 16, 17, 18, 19, 20, and 21 are routes of the trunk line.

Exchanges 3 and 7 are exchanges for executing dynamic routing, route 13 is a direct route between exchanges 3 and 7, routes 14 to 16 are detour routes seen from exchange 3, and exchanges 4, 5 and 6 are exchanges. It is a detour destination exchange seen from points 3 and 7.

FIG. 2 shows the signal format of the common line signaling system. 41 is a transmission control unit, 42 is a network address, 43 is a user signal, 44 is a transmission control unit, and 45 is a field for displaying the accumulated transmission delay time. , 46 is a field showing a flag used by the echo canceller, and 47 is a field showing a call transfer capability.

A call originating from the exchange 1 and received by the exchange 9 will be described as an example.

When a call originates in the exchange 1 and the exchange 1 selects a line in the route 11, the transmission delay time relating to the line is stored in the field 45 indicating the accumulated transmission delay time.
And relay to the exchange 2.

If the exchange 1 is a subscriber exchange, the field 45 shows the transmission delay time from the subscriber exchange to the subscriber terminal in the subscriber transmission system (eg, analog subscriber line, ping-pong transmission subscriber line, remote). Accommodation subscriber line,
It is set in the process of call processing according to the wireless line, etc.,
Further, when the exchange 1 is a transit exchange, the transmission delay time accumulated in each exchange up to the exchange 1 is set in the preceding exchange.

The transmission delay time relating to the set line in the route 11 includes the transmission delay time of the transmission cable and the transmission delay time of the terminal equipment such as the multiplexer and the cross connector.

The exchange 1 and the like store these values as route information.

The call arrives at exchange 2 and exchange 2 routes 1
When 2 is selected, the transmission delay time relating to the selected line in the route 12 is added to the field 45 and relayed to the exchange 3 as in the exchange 1.

When the call arrives at the exchange 3, the exchange 3 first selects a line in the route 13 which is a direct route, and when all the lines in the route 13 are blocked, the route 16 to the route 16 which are the detour candidates. Select one of the best routes.

The condition for selection is that the route has a high probability of being bypassed and connected to the exchange 7 and that the quality condition regarding the transmission delay time is satisfied.

The route selection algorithm relating to the former condition is not the object of the present invention, and some methods have already been reported, so the description thereof will be omitted.

The exchange 3 is a route with a high probability of being connected,
For example, assuming that the route 14 is selected, then the accumulated transmission delay time shown in the field 45 and the transmission delay time and the allowable transmission delay time regarding the selected line in the route 14 meet the transmission delay time condition of the transmission quality. It is determined whether or not.

The transmission delay time relating to the line in the route 14 is the total transmission delay time to reach the exchange 7 via the route 14, the exchange 6 and the detour route 17, which is the exchange 3
It is stored in the route information of.

.. If the sum of the accumulated transmission delay time and the transmission delay time for the selected line in route 14 is within the allowable transmission delay time, add the transmission delay time for the selected line in route 14 to the accumulated transmission delay time field. Divert the call to route 14.

If the sum of the accumulated transmission delay time and the transmission delay time for the selected line in the route 14 exceeds the allowable transmission delay time, the exchange 3 determines that the route having the next highest connection probability,
For example, the route 16 is selected, and the same transmission delay time condition is checked.

As another embodiment, it is assumed that an echo canceller is inserted in the line selected by the exchange 2.

In this case, the exchange 2 adds the transmission delay time generated in the echo canceller and the transmission delay time relating to the line in the route 12 to the accumulated transmission delay time, and uses the echo canceller in the field 46 of the common line signaling system. Is set to logic 1 and relayed to the exchange 3.

The exchange 3 knows from the flag of the field 46 that the echo canceller is used on the connection route, and uses the value when the echo canceller is inserted as the allowable transmission delay time.

The exchange 3 compares the sum of the accumulated transmission delay time and the transmission delay time concerning the line in the route 14 with the allowable transmission delay time when the echo canceller is inserted. If the former is less than the latter, Route 14 is selected, and if the former exceeds the latter, another detour route is selected.

Normally, when the echo canceller is used, the allowable transmission delay time is longer than when it is not used, so that the selection range of the detour route is expanded.

As another embodiment, the exchange 1 is a conventional STM (Synchronous Transfer Mode) digital exchange, and when the route 11 is converted to ATM, an STM signal is sent to the route 11 line.
A device for converting / reverse converting to M cell information is inserted.

When converted to cells, for example, a voice signal causes a delay of about 6 ms. Therefore, the value added to the cumulative transmission delay time is the cell conversion / transmission delay time related to the selected line in the route 11. The delay of the inverse transformer is added.

The following are examples of cases based on call attributes.

For example, in an ISDN 64 kbps circuit-switched call, there are voice, 3.1 KHz audio, and 64 kbps non-restricted transmission capacity, which are shown in the field 47.

The allowable transmission delay time is generally longer in the case of unrestricted 64 kbps than that of voice and 3.1 KHz audio. Therefore, the above-mentioned alternative route is selected by using the allowable transmission delay time corresponding to these transmission capabilities. By doing
The selection range of the detour route is expanded.

In the above embodiment, the transmission delay time for the selected line is set in the originating exchange, but the present invention is not limited to this.

For example, the line selected by the exchange 1 can be identified by the exchange 2 as a matter of course. Therefore, when the exchange 2 receives the line, the exchange 2 calculates the transmission delay time relating to the selected line in the route 11 as the accumulated transmission delay time. May be added to.

Further, when the inserted device can be grasped only by the originating exchange, the originating exchange can add the transmission delay time of the device to the accumulated transmission delay time to obtain the transmission delay time which the terminating exchange can grasp. The destination exchange may be configured to add to the cumulative transmission delay time.

In the embodiment shown in FIG. 1, the dynamic routing is performed only once between the exchange 1 and the exchange 9, but the transmission delay time is cumulatively transmitted even in the exchange where the dynamic routing is performed as described above. Since it is added to the delay time, appropriate dynamic routing is performed even if there are a plurality of exchanges that execute dynamic routing on the connection route.

FIG. 3 shows an example of a flowchart of processing related to the present invention of the exchange 1, for example, and FIG. 4 shows an example of a flowchart of processing related to the present invention of the exchange 3 which performs dynamic routing.

In the example of FIG. 3, when a call occurs in the exchange and a line in the route is selected (S101, S102), the transmission delay time relating to the selected line in the route is read and added to the cumulative transmission delay time ( S103).

When the echo canceller is inserted (S104), the flag of the field 46 indicating the use of the echo canceller is set to logic 1 (S105) and relayed to the next exchange (S106).

In the example of FIG. 4, for example, in the exchange 3 which executes the dynamic routing, the direct route is first selected (S20
1, S202), when an empty line of the direct route is captured, the transmission delay time for the selected line in the direct route is added to the accumulated transmission delay time, and the result is relayed to the next station (S2).
03 to S205).

When all the lines of the direct route are blocked, the optimum detour route is selected (S207), and when the detour route exists and the line is available (S208, S2).
09) Next, it is checked whether or not the echo canceller use flag is logical 1 (S210). If the echo canceller use flag is not logical 1, the allowable transmission delay time when the echo canceller is used is read. The permissible transmission delay time not using the canceller is read (S211,
S212).

If the sum of the transmission delay time for the selected line in the detour route and the cumulative transmission delay time is less than or equal to the allowable transmission delay time, the transmission delay time for the selected line in the detour route is added to the cumulative transmission delay time. Then, the data is relayed to the next station (S213, S214, S204, S205), and in the other cases, the next desired alternative route is selected and the same processing is performed.

If there is no detour route to be selected, the call is processed as a call loss (S215).

FIG. 5 shows an embodiment based on call attributes, and shows only the modified portion of the flowchart of FIG.

Call attributes, voice, 3.1KHz audio,
4 is the same as that of FIG. 4 except that the permissible transmission delay times corresponding to 64 kbps non-limitation are read out (S301, S302, S303).

FIG. 6 is a diagram showing an embodiment of automatic updating of the transmission delay time relating to the line according to the present invention.
53 is a transmission terminal station, 61, 62, 63, 64, 65 are transmission links, 71 is an operation system, 81, 82,
83, 84 and 85 are control links.

The route 12 is the transmission links 61, 62, 63.
It consists of

In the description of the above embodiment, the route 12
The transmission delay time for the internal line is the sum of the transmission delay time of the transmission terminal stations 51, 52 and the transmission delay time of the transmission links 61, 62, 63, and this value is preset in the exchanges 2, 3.

However, if the transmission link 62 fails, for example, failure information is reported to the operation system 71 via the control link 82, and the operation system 7 is notified.
Reference numeral 1 indicates switching of transmission links by transmitting terminal stations 51, 52, 53.
Instruct.

Therefore, the transmission terminal station 51-transmission link 62
-The path of the transmission terminal 52 is the transmission terminal 51-the transmission link 64.
-Transmission end station 53-Transmission link 65-Transmission end station 52 switches to the path, so that the transmission delay time for the lines in route 12 differs from the previous value.

On the other hand, for example, the operation system 71 uses the route 1 when the route 12 is switched.
2, a new transmission delay time is calculated, this value is transferred to the exchanges 2 and 3 via the control links 81 and 85, and the transmission delay time stored in the exchanges 2 and 3 is updated.

When ATM is used between the exchanges 2 and 3, the OAM (Operation,
It is possible to measure the delay time of a VC (Virtual Circuit, corresponding to an STM line) or a VP (Virtual Path, corresponding to a path that is a bundle of STM lines) in the route 12 by using an Administration and Maintenance cell. Therefore, it is possible to automatically update the transmission delay time periodically or by using the switching of the transmission link or the path as a trigger.

Although the embodiment of automatic updating of the transmission delay time regarding the line has been described, it is clear that the updating of the transmission delay time can be performed manually by an operator without any problem.

Although the above embodiment is an example of the dynamic routing relating to the line and the VC, the present invention is a path that is a bundle of lines and a VP that is a bundle of VCs (hereinafter, unless otherwise specified, a path is an STM path). And VP).

For example, although it has been described in FIG. 1 that the route 12 is set between the exchanges 2 and 3, the network architecture (for example, special feature network architecture, NTT R & D, vol. 42, No. 2, (1993)
Strictly speaking, a path is set between the exchange 2 and the exchange 3.

Although the transmission link 62 is switched to the transmission link 64 in FIG. 6 when there is a failure, in the actual network, there are a plurality of switching candidate transmission links, and the optimum transmission link is switched from among them.

One of the selection criteria in this case is that the transmission delay time of the path satisfies the specified value.

For example, when the terminal station 51 detects a failure in the transmission link 62 and switches the transmission link, the transmission terminal station 51
Based on the accumulated transmission delay time up to and the transmission delay time related to the switching transmission link and the allowable transmission delay time, efficient switching of paths (path routing) can be performed by selecting the switching transmission link as in the case of dynamic routing. Becomes

That is, within the control link (A
In the case of TM, a field for displaying the accumulated transmission delay time is provided in the OAM cell, and the transmission terminal station (switch 2 in FIG. 6) which is the end point of the path is provided.
Includes a path terminating function), for example, cumulatively adds the transmission delay time relating to a transmission link that is used regularly to the cumulative transmission delay time, and relays to the next transmission terminal station. Similarly, the transmission delay time relating to the transmission link to be used is cumulatively added to the cumulative transmission delay time and relayed to the next transmission terminal station to switch the transmission link (path) (transmission terminal station 51 in FIG. 6). In (1), for example, the cumulative transmission delay time may be stored, and the sum of the cumulative transmission delay time and the transmission delay time regarding the switching transmission link may be selected to be equal to or less than the allowable transmission delay time.

[0086]

As described above, according to the present invention, the transmission delay time that actually reaches the exchange that performs dynamic routing, the use condition of the echo canceller, and the allowable transmission delay time according to the call transmission capability are used. Since the dynamic routing is performed by using the dynamic routing, the application range of the dynamic routing is expanded as compared with the conventional method.

As a result, the dynamic routing can be effectively operated.

Further, since the transmission delay time and the like that are actually used are used, it is possible to operate the dynamic routing which is safe for the communication quality.

With regard to the path routing, it is possible to operate the path routing efficiently and safely with respect to the communication quality for the same reason.

[Brief description of drawings]

FIG. 1 is a communication network configuration diagram for explaining an embodiment of the present invention.

FIG. 2 is an explanatory diagram of a signal format of a common line signaling system.

FIG. 3 is a flowchart example 1 of processing of the exchange according to the present invention.

FIG. 4 is a flowchart example 2 of processing of the exchange according to the present invention.

FIG. 5 is a flowchart example 3 of processing of the exchange according to the present invention.

FIG. 6 is an example of automatic updating of transmission delay time.

[Explanation of symbols]

1,2,3,4,5,6,7,8,9 switch 11,12,13,14,15,16,17,18,1
9, 20, 21 Route 41 Transmission control unit 42 Network address 43 User signal 44 Transmission control unit 45, 46, 47 Field 51, 52, 53 Transmission terminal station 61, 62, 63, 64, 65 Transmission link 71 Operation system 81, 82,83,84,85 control links

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI Technical display location H04L 12/56 12/50 H04Q 3/545 8843-5K 8732-5K H04L 11/20 103 A

Claims (6)

[Claims] 1. A dynamic routing control method in a communication network using dynamic routing, wherein each exchange on a connection route sets a transmission delay time for a line in a selected route in a user signal of a common line signaling system. In a switch that adds to the first field and executes dynamic routing, the sum of the cumulative transmission delay time shown in the first field and the transmission delay time of the line in the selected route is a predetermined allowable transmission delay time. A dynamic routing control method characterized in that the line of the route is used in the following cases. 2. A second field indicating whether or not the echo canceller is inserted in the line selected by the exchange on the connection route is provided in the user signal of the common line signaling system, and the exchange on the connection route selects the echo canceller. When it is used, it is displayed in the second field, and in the switch which executes dynamic routing, the use of the echo canceller on the connection route is judged from the contents of the second field, and the echo canceller is used or not used. 2. The dynamic routing control method according to claim 1, wherein a predetermined allowable transmission delay time is used. 3. The dynamic routing control method according to claim 1, wherein an allowable transmission delay time predetermined according to the transmission capability is used. 4. The dynamic routing control method according to claim 1, wherein when the transmission delay time relating to the line is changed, the transmission delay time relating to the line stored in the exchange is automatically updated. 5. The dynamic routing control method according to claim 2, wherein a predetermined allowable transmission delay time is used according to the transmission capability. 6. A dynamic routing control method in a communication network using dynamic routing, wherein a third field for displaying a cumulative transmission delay time is provided in a control link between transmission terminal stations, and a transmission terminal configuring a path is provided. The station adds the transmission delay time related to the transmission link to be used to the third field and relays it to the next transmission terminal station, and at the transmission terminal station which switches the path, the accumulated transmission delay time shown in the third field and the switching A dynamic routing control method comprising path routing control for routing to a transmission link when the sum of the transmission delay time for the transmission link is equal to or less than a predetermined allowable transmission delay time.