JPH0370330A - Routing control system in atm communication - Google Patents

Abstract

PURPOSE:To improve the throughput of a network without degrading service quality by calculating a load and a load fluctuation added newly as to all output paths, comparing the load with the load fluctuation calculated to each route with an optimum route selection means and selecting a route where both values are small. CONSTITUTION:When an application parameter storage means 11 receives an attribute parameter applied by a connection request call, a load and load fluctuation calculation means 12 uses the information of a route load and load fluctuation storage section 14 to calculate the load and load fluctuation added newly as to all output paths. Then the load and load fluctuation values calculated by each route are compared with an optimum route selection means 13 to select a route where both values are small. Thus, the throughput of the network is improved without degrading the service quality required for an asynchronous transfer mode ATM communication.

Description

[Detailed Description of the Invention] [Required 111] Regarding a routing control method in asynchronous transfer mode (ATM), routing control for ATM communication that can improve network throughput without degrading the service quality required for ATM communication. For the purpose of providing a system, the communication control unit of the ATM is equipped with a load/variation value storage unit for each route that holds load and load variation information applied to each of all outgoing routes, and the communication control unit of the ATM is equipped with a load/variation value storage unit for each route that holds load and load variation information for each of all outgoing routes. When the declared attribute parameter is received by the declared parameter holding means, the load and
The fluctuation value calculation means calculates the newly added loads and load fluctuations for all output routes using the information in the route-by-route load and fluctuation value storage section, and the load and fluctuation values calculated for each route are used as the optimal route selection means. The configuration is configured so that the route with the smaller values of both values is selected.

[Industrial Application Field] The present invention relates to a routing control method in asynchronous transfer mode (ATM) communication.

In recent years, broadband (SDN) (Integrated
5services Digital Network
) ATM (Asynchronous
(US Transfer Mode) is being actively researched. Routing control is one of the traffic control methods for ATM communication.

There are two types of routing control: one is used to determine the route when setting up a call, and the other is used as a prostitute control to change the route at the time of prostitution, but routes that have already been set for both purposes. Rerouting that changes the cell order causes an inversion of the cell order, which is undesirable. Therefore, routing at the time of call setup, which does not require cell order preservation processing, is important.

On the other hand, in ATM communication, various types of traffic such as voice, data, video, etc. with different information bearer speeds and burstiness are handled uniformly, so if traffic with strong burstiness is mixed, fluctuations in the traffic added to the communication path may occur. There is a problem that the quality of the requested service deteriorates as the size of the device increases, and a solution to this problem is desired.

[Prior Art] In ATM communication, transfer is performed by inserting fixed-length (for example, 64-bit) packets called cells into vacant time slots, and the effective transfer speed can be increased by increasing or decreasing the number of cells. It can be changed. A cell consists of a cell and data, and the header contains information such as the destination.

The network looks only at the contents of the header, exchanges each cell, and delivers it to the other party. In this case, continuous signals such as audio and moving images are also converted into cells and transmitted, and then converted back into continuous signals at the receiving end.

In ATM communication, as mentioned above, information with various characteristics is transmitted, and information with extremely high communication speeds (several tens of MHz, such as videos) and information with low speeds, such as voice, are transmitted on the transmission path. are transmitted in a mixed manner. In this case, in addition to continuously occurring information (data communication information), there is also intermittent bursty information (audio, video information, etc.), which causes problems in the transmission path that multiplexes and transfers cells. Routing control is required.

In conventional ATM communication, ATM communication itself is a new technology, so it cannot be cited as a routing control method, but it uses the traffic control and prostitute control technologies used in conventional circuit switching and synchronous packet switching. It is possible to use it. In other words, in the case of circuit switching,
This method determines whether the line is occupied or not and selects the outgoing route. In the case of packet switching, the method calculates the number of packets currently assigned to the outgoing route transmission path. We were able to choose a transfer route that had free space.

[Problem N to be solved by the invention] As mentioned above, ATM communication (ATM communication network and ATM
Switches (exchanges) transfer information of different speeds and characteristics (continuous vs. bursty, etc.), so there are problems with routing control to select which route to assign a call (cell) that has generated a connection request. was there.

In other words, when a high-speed, bursty connection request call is assigned to a route, many cells will occur at the same time, although this will depend on the characteristics (bursty nature and transfer speed) of the multiple calls that have been transferred up to that point. (peak) and the transmission capacity (transmission capacity) is exceeded, in which case cell discard (cells are discarded without being transferred) occurs. Such cell discard can be avoided by increasing the capacity of the buffer provided within the network, but this is not preferable for information that requires real-time performance, such as voice, because the delay time becomes large.

On the other hand, if routing is controlled so that the maximum peak at which cells occur is always less than the transfer capacity of the transmission path, network throughput can be maximized from the perspective of efficiently using common resources within the network. I can't.

The present invention is capable of improving network throughput without degrading the service quality required for ATM communication.
The purpose is to provide a routing control method for TM communications.

[Means for Solving the Problems] FIG. 1 is a basic configuration diagram of the present invention, and FIG. 2 is a diagram illustrating the principle of the present invention.

In FIG. 1, IO is a communication control unit, 11 is a declared parameter holding means, 12 is a load/variation value calculation means, 13 is an optimal route selection means, 14 is a load/variation value storage unit for each route, 15 is a temporary memory, 16 represents a route switching section.

In the present invention, information on a connection request call is configured to include attribute parameters included in the call as declaration information, and when the ATM communication control device obtains the load and fluctuation rate in the attribute parameters of the declaration information, each output Calculate each value when the call is newly added to the current load and fluctuation rate data of the route, select the route with the lowest value, and control the transfer of the call. It is something.

[Function] Before explaining the function of FIG. 1, the present invention will be explained in detail with reference to FIG. 2.

A burst traffic model is shown in FIG. 2A. This is shown to consider the maximization of network throughput in terms of the multiplexing characteristics of burst trough ink. In the figure, α (-1/α) is the average burst duration, β-' (=1/α)
β) is the average burst occurrence interval time, T is the cell formation time, N
c (=α-1/T) represents the average number of cells generated during the burst duration.

FIG. 2B shows how the traffic load on the transmission path changes over time when such bursty cells and continuous cells are multiplexed and transmitted. As described above, load fluctuations occur due to burst data, and if the amplitude of the fluctuations is large, a situation occurs in which the transmission capacity is exceeded (cell discard occurs).

Therefore, as an index indicating the degree of bursting of such burst trough ink, the square coefficient of variation (expressed as SVC) of the cell generation interval is used to determine the multiplexing characteristic. This squared coefficient of variation is defined as variance/(mean squared),
It shows the ratio of fluctuation to the average, and is expressed, for example, by the following equation.

2-Nc-' (1+γ-1)! 1tJc This square fluctuation coefficient SvC and the burst characteristics are shown in Figure 2C.
There is a relationship shown in 0, and the burst parameter γ=β−1/
It can be seen that the larger the ratio of α-1 and the larger Nc, the larger the coefficient of square variation becomes.

The larger the coefficient of variation and the larger the average number of cells generated, the higher the cell discard rate.

In order to maximize network throughput,
It can be seen that it is necessary to balance at least the cell load (number of cells generated) on each route. However, ATM
In communication, various calls with different bandwidths and burst characteristics are handled, so maximization cannot be achieved only by balancing the cell load (number of cells generated). Therefore, in the present invention, calls are allocated so that the variation coefficients of each route are also balanced.

Combining these, the present invention uses the principle of routing control as balancing the cell load and the coefficient of variation of cell generation on each route.

Next, the operation of FIG. 1 will be explained. The basic configuration shown in FIG. This configuration is also applied to a link routing control method (including a case where the link is configured in multiple stages).

A connection request call from a terminal or a transmission path first declares the attribute parameters of its own call (when the request is generated). This attribute parameter includes peak bandwidth (highest transfer rate V,
), average burst duration (α-1), average burst occurrence interval time (β-1), average number of cells generated during burst duration (Nc), or average load (a)
and the coefficient of variation (same as the squared coefficient of variation SvC above).

Note that the average load is given, for example, by the following equation, and VT is the maximum bandwidth (speed) of the transmission path.

1+γ ■7 The above declaration parameters are the communication control unit 10 of the ATM.
It is held in the declared parameter holding means 11 of. This declared parameter is then supplied to the load/variation value calculation means 12, which retrieves the current load and variation value for each route from the route-by-route load/variation value storage section 14, and makes the connection request call for each route. Calculate the load (average load) and fluctuation value (corresponding to the squared coefficient of variation in FIG. 2 above) that will occur on each route when the route is connected. That is, the load (average load) due to connection request calls is calculated using the above equation (1), and the fluctuation value is calculated using the above equation (2). This calculation is performed for all possible routes and the results are stored in temporary memory 15.

When the calculation of the load and variation value for each route is completed, the optimal route selection means 13 then looks at the calculation results stored in the -time memory 15 and selects the route with the least load and variation value. In this case, the selection method can be selected arbitrarily, but it may be a method of checking either the load or the fluctuation value and selecting the route with the smallest value.

When the optimal route is selected, the information is sent to the route switching unit 1.
6 to switch and connect the cell of the connection request call to the selected outgoing route.

As described above, in the present invention, calculations are performed for each candidate route using the load and fluctuation values that are the parameter information declared from the connection request call, with respect to the current load and fluctuation values of each route. By selecting the route with the smallest load and variation value from among them, it is possible to equalize the load and variation among the routes and improve the throughput in ATM communication.

[Example] Fig. 3 is a control flow diagram of a call connection request of the embodiment, Fig. 4 is a control flow diagram of a call termination request of the embodiment, and Fig. 5 is a control flow diagram of a call termination request of the embodiment.
A configuration diagram of the TM communication network, FIG. 6 is a configuration diagram of the ATM switch of the embodiment, FIG. 7 is a configuration diagram of the ATM switch of the embodiment, and FIG. 8 is a configuration of the database used in the ATM communication network/switch of the embodiment. FIG. 9 is a configuration diagram of a database used in an embodiment of the ATM switch.

The control flow for a call connection request in FIG. 3 and the control flow for a call termination request in FIG. 4 are based on the structure of each embodiment shown in FIGS. is executed in each control unit. In addition, the load used for calculation in each control flow above,
Information such as load fluctuations is shown in Figure 8 (ATM communications network routing control and ATM switch routing control).
Alternatively, it is stored as a database with the contents shown in FIG. 9 (ATM switch routing system m), and is stored in the database shown in the configuration of each embodiment in FIGS. 5 to 8.

To explain the call connection request control flow of the embodiment shown in FIG. 3, when performing ATM communication from the terminal side, a call connection request and call attribute parameter declaration information are transmitted to the ATM communication network (step 30). When this is accepted by the communication network (step 31), the control device uses the declared parameters and the load and load change information for each data route in the database to apply newly added loads and load changes to all outgoing routes. Calculate (step 32).

A concrete example of this calculation will be explained in ◆-4.When Yuko i declares VP (peak bandwidth), α subtraction (average burst duration time), and β-′ (average burst occurrence interval time) when making a call, As mentioned above with respect to FIGS. 1 and 2 (see section ``Effect''), 2(1).

Calculate the average load ai and fluctuation SCV of call i by (2). Next, the sum of the average loads of already accepted calls on each route, Al-1, and the sum of fluctuations, C,-1, are determined by the following equations. However, it is assumed that i-1 calls are accepted on route j.

A i −1+ j ”Σ ak+jCI−,,1
=Σ5VCk.

The sum of the average load and the sum of fluctuations are the above a and SC, respectively.
By adding V, it is possible to obtain the load and fluctuation when the call for which the connection request has been made is connected to that route. Note that when information on average load and fluctuation is included as the declared information from the terminal, the above calculation is performed using that information. The calculation results for each exit route obtained in this manner are stored in a memory (not shown) included in the control device.

Next, the load and fluctuation values of each route obtained as a result of calculation are compared to select an exit route with uniform load and minimum load fluctuation (step 33), that is, the average load of each route. Find a route j that minimizes the sum A i -1+j+al and the sum of fluctuations c, -, , +scv.

When an outgoing route is selected, the database (subscriber information and outgoing route information) is updated with the declared parameters of the connection request call.

Subsequently, communication path control is performed to connect the call requested for connection to the selected outgoing route (step 35).

Next, a control flow of a call termination request in the embodiment shown in FIG. 4 will be explained.

When a call termination request is transmitted from the terminal (step 40), the network side accepts the call termination request (step 41). Next, the call requesting termination is searched for from the subscriber information in the database (Stennob 42), and when detected, the call is terminated based on the declared parameters of the subscriber whose call is to be terminated, thereby calculating the load and load fluctuation ( Step 43). In this case, the value of the subscriber is removed from the data on which the load and load fluctuation are calculated, and calculations are performed using only the data of other currently connected calls.

Once the calculation results are obtained, the output route information (
(stored in the database) is updated (step 44). Subsequently, the subscriber whose call is to be terminated is deleted from the subscriber information (stored in the database) (step 45).

Next, to explain the configuration of the ATM communication network shown in Figure 5, 50 to 52 in Figure 5 represent telephone terminals, data terminals, 200 image terminals, etc. installed on the terminal side, and each terminal is connected to the W4 terminal device. It is connected to the ATM communication network from the network termination device 53. The ATM communication network is connected to a plurality of ATM exchanges 54 via transmission lines, and cells are transferred. Each ATM switch is provided with a database 55, which stores subscriber information (parameter information declared from a terminal, etc.) and outgoing route information according to the present invention.

FIG. 6 shows a configuration diagram of an ATM switch according to an embodiment, in which lines from an M4 termination device 60 in which each subscriber's terminal is accommodated are connected to a multiplexing device (indicated by MUX) 61 of the switch and are multiplexed. The ATM switch 63 is then connected and output to the destination terminal or exchange. 62 in the figure is a signal processing device (displayed by SIG), 64 is A
65 is a call processing device (indicated by CPR) that performs routing control according to the present invention; and 66 is subscriber information and outgoing route information used for routing control according to the present invention. This is a database that stores .

FIG. 8 shows the configuration of a database used in the routing control of the ATMiill network and A7M exchange shown in FIGS. 5 and 6 above.

A in FIG. 8 is subscriber information, which stores various information regarding accepted calls (connected calls) in response to call connection requests from each subscriber.

That is, as shown in the figure, it is composed of a subscriber line number (indicated by No.), a call number, an outgoing route number, and values representing peak band, average band, and burst characteristics as declared parameter values. Information on all subscribers who made accepted calls is stored here, and is deleted when the call is terminated.

B in Figure 8 shows outgoing route information, and for each outgoing route, information on outgoing route number (indicated by No.), outgoing route load, and outgoing route 1- load fluctuation information is shown for all white routes. Stored.

FIG. 7 shows a configuration diagram of the ATM switch of the embodiment. This ATM switch is a specific configuration example of an ATM switch in the exchange shown in FIG.

The ATM switch in FIG. 7 has a multi-stage switch configuration,
In the figure, 70 is a multiplexer MUX, 71 is a first stage switch, 7
2 represents a primary link, 73 represents an intermediate switch, 74 represents a secondary link, 75 represents a final stage switch, 79 represents a link information database, 80 represents a subscriber information database,
76 to 78 are 62 (SIG) and 64 (L
PR), 65 (CPR).

In the case of the ATM switch shown in FIG. 7, an input connection request call is sent from the first-stage switch 71 to the intermediate switch 73 via the second-stage link 72. The signal is output from the final stage switch 75 to the output route via the secondary link 74.

The switch control is executed under the control from the communication path control device (LPR) 77, and is executed under the control from the communication path control device (LPR) 77. A call processing device (CPR) 78 performs routing control to determine which of the secondary links 74 the outgoing route is connected to.

The call processing device 78 is provided with a link information database 79 and a subscriber information database 80, and performs processing according to the control flow shown in FIGS. 3 and 4.

FIG. 9 shows the structure of the database used in the embodiment of the ATM switch.

A in FIG. 9 shows a database of subscriber information,
Various information regarding accepted calls (connected calls) in response to call connection requests from each subscriber is stored, and the contents are the same as those shown in FIG. 8A, so a description thereof will be omitted.

In B of FIG. 9, link numbers,
Load and load fluctuation information is stored. In the ATM switch routing control shown in Fig. 7,
In step 33 of the control flow in FIG. 3, the exit route with uniform load and minimum load fluctuation is selected.
- It is necessary to make a judgment to match the next link and the secondary link (connection of both links is possible).

Once the primary and secondary links with the least load and variation have been matched, the call processing device 78
A control signal is output to 71, 73, and the communication path control device 77 controls each switch 71, 73 to connect the initial switch to which the requested call was connected, the selected primary link, the secondary link, and the outgoing route. and 75.

[Effects of the Invention] According to the present invention, it is possible to reduce the cell discard rate in the entire ATM communication network, thereby improving network throughput. Furthermore, the cell discard rate in ATM exchanges and ATM switches can be reduced, and delays can be reduced.

That is, the smaller the load, the lower the cell discard rate, and the smaller the fluctuation, the lower the cell discard rate.

lO: Communication control unit 11: Declaration parameter holding means 12: Load/fluctuation value calculation means 13: Optimal route selection means 14: Load/variation value storage section for each route 15 temporary memory 16: Route switching section

[Brief explanation of drawings]

Fig. 1 is a basic configuration diagram of the present invention, Fig. 2 is a diagram explaining the principle of the present invention, Fig. 3 is a control flow diagram of a connection request call in the embodiment, and Fig. 4 is a control flow diagram of a call termination request in the embodiment. 5 is a block diagram of the ATM communication network of the embodiment, FIG. 6 is a block diagram of the ATM exchange of the embodiment, FIG. 7 is a block diagram of the ATM switch of the embodiment, and FIG. 8 is a block diagram of the ATM switch of the embodiment. FIG. 9 is a diagram showing the configuration of a database used in a communication network/exchange. FIG. 9 is a diagram showing the configuration of a database used in an embodiment of an ATM switch. In Figure 1,

Claims (3)

[Claims] (1) In a routing control method in asynchronous communication mode (ATM) communication, call connection request information includes attribute parameters related to the load and load fluctuation of the call as declaration information, and the ATM communication control unit (10) includes a route-by-route load/variation value storage unit (14) that holds load applied to each outgoing route and load variation information; Upon reception, load/fluctuation value calculation means (12)
The newly applied loads and load fluctuations are calculated for all output routes using the information in the route-by-route load/variation value storage section (14), and the load and fluctuation values calculated for each route are used by the optimal route selection means ( 13) A routing control method in ATM communication, characterized in that a route having smaller values is selected by comparison. (2) A where multiple ATM exchanges are connected by transmission lines
In the routing control system in the TM communication network, call attribute parameters are transferred from the transmission path to the ATM when a call connection is requested.
The communication network is notified, and the ATM communication network control device controls each ATM that makes up the communication network.
The control device includes a database that stores load and load fluctuation information applied to each of all outgoing routes of the exchange, and when the above-mentioned connection request call is received, the control device uses the attribute parameters and the information in the database to update each data route. An ATM communication network characterized by calculating newly added load and load change information for each outgoing route, equalizing the load on each outgoing route, selecting the route with the minimum load change, and notifying the corresponding ATM switch. Routing control method. (3) In a routing control method in an asynchronous transfer mode (ATM) switch, when a call connection is requested, the subscriber terminal transmits the call attribute parameters to the AT
The control device of the ATM switch is equipped with a database that stores the load applied to each of all the links of each ATM switch and load change information, and the control device notifies the M switch that there is the connection request call. Using the attribute parameters and the information in the database, calculate the newly added load and load fluctuation information for each link, and select the route that equalizes the load on each outgoing route and minimizes the load fluctuation, and performs exchange control. A characterized by performing
Routing control method in TM exchange.