JPH09130386A - Atm communication network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the cell rejection rate to obtain an asynchronous transfer mode communication network (ATM communication network) having a high throughput by selecting a route for a user based on route information recorded when there is connection request. SOLUTION: An ATM exchange 20(40) is provided with a protocol controller 21 as a means which supports the protocol by which a user terminal equipment 3 adaptively performs the flow control to an ATM communication network. A route information gathering part 22 of the ATM exchange 20 gathers and records new route information, which includes the number of currently used band idle information hops (the number of stages of repeating exchanges) of virtual paths(VP) related to plural routes set between the exchange 20 and another exchange as the subscriber exchange on the terminating side, as the subscriber exchange on the originating side whether connection is requested or not. The protocol controller 21 selects a route for the user based on this recorded route information in response to connection request.

Description

Detailed Description of the Invention

[0001]

The present invention is used in an asynchronous transfer mode communication network (hereinafter referred to as an ATM communication network). The present invention is used for virtual path (hereinafter referred to as VP) band control and route selection. In particular, the present invention relates to a technique for reducing the time from when a connection request or a band increase request is sent from a user terminal device until the band is actually set or increased.

[0002] In this specification, a VP is a virtual communication path set in a physical transmission line of one section of an adjoining relay exchange or subscriber exchange in the network, and a route is from one subscriber exchange. It is a communication path that is set up to other subscriber exchanges via a plurality of VPs.

[0003]

2. Description of the Related Art A VP which is a virtual transmission line on a physical transmission line
There is known an ATM communication network which is provided with and performs communication. FIG. 12 shows the concept of this conventional ATM communication network. Figure 12 is AT
It is a figure which shows the concept of M communication network. In FIG. 12, 4 ₁ ,
Reference numerals 4 ₂ , 4 ₃ and 4 ₄ are ATM exchanges, 7 ₁ , 7 ₂ and 7 ₃ are relay transmission lines which are physical transmission lines, and 3 ₁ and 3 ₂ are user terminal devices. In the ATM communication network, a VP is set on the physical transmission line. Further, a plurality of virtual paths (hereinafter referred to as VC) are set in the VP. User terminal device 3 ₁
Or when 3 ₂ communicates, first, a route is selected and a VC is set in the VP included in the route.
There are two methods of setting the VC, one is to continuously secure the VC and the other is to secure the VC only for the communication time according to the request. Here, the latter is equivalent to SHM (Short Hold Mod).
An example of e) is shown.

In the conventional example, the user terminal devices 3 ₁ and 3 ₂ have already established a route to the ATM communication network when they want to perform file transfer or the like. However, the VC band included in the route is zero.

A resource management cell (hereinafter referred to as an RM cell) is sent to the ATM network to request acquisition of a VC band. Here, it is assumed that the user requests a VC band of 10 Mb / s. ATM switches 4 ₁ , 4
_{In 2} , 4, ₃ and 4 ₄ , the content of the RM cell is “10 Mb /
If there is a desired band in the currently used ATM switches 4 ₁ to 4 ₄ and relay transmission lines 7 _{1 to} 7 ₃ , the resources are secured and the ATM switch in the next stage is read. Transfer the RM cell, which is the VPI (Virtual Path Identifier) / VCI used by this user.
Since the (virtual channel identifier) is identified by another bit in the header called PTI (payload type identifier) number, the route used by this user can be automatically transferred. When a plurality of routes exist, one route becomes NG (non-permitted) and then another route is retried based on the protocol described above.

[0006]

FIG. 13 is a diagram showing a timing chart of RM cell handling in each ATM switch. As shown here, each ATM switch 4 ₁
At ~ 4 _4, the time to access the sky information Other resources is to some extent necessary.

FIG. 14 is a diagram showing a time response to a user request. In this way at the time to increase the bandwidth, it takes the response time in order to go to check the sky bandwidth to each ATM exchange 4 _{1-4 4.} This is a delay for the request, which is a service problem. Furthermore, the actual network has a long distance and a large number of transit exchange stages. In this case, there is a problem particularly in response time. Further, in an actual network, a plurality of routes (routes) exist instead of one route, but it takes time in the method described above to select an appropriate route from a plurality of routes in a short time. is there.

The present invention has been made in view of such a background, and an object thereof is to provide an ATM communication network having high speed and flexibility. It is an object of the present invention to provide an ATM communication network that simplifies the hardware configuration of an ATM switch and can instantly find an optimum route from a plurality of routes. An object of the present invention is to provide an ATM communication network having a high cell throughput with a reduced cell discard rate.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a subscriber switching apparatus grasps information including empty bands of a plurality of routes through which the connection passes in advance when there is no band change request for newly setting a route. The most important feature is that when a user requests route setting, bandwidth change, etc., the optimal route is determined by the protocol controller in the exchange in which the subscriber is accommodated, and permission or denial is given. It has a feature. Therefore, the portion corresponding to the protocol used by the user terminal device only needs to be provided in the subscriber exchange which directly accommodates the user terminal device, and the relay exchange and other ATM exchanges correspond to complicated protocols in real time. It does not need to have a function.

That is, the present invention comprises a plurality of subscriber exchanges, a plurality of physical transmission lines that connect the plurality of subscriber exchanges to each other, and a repeater exchange inserted in the plurality of physical transmission lines. , A plurality of routes are set between the plurality of subscriber exchanges, the subscriber exchange selects an optimum route from the plurality of routes, and an SHM protocol that allows a user to provide a communication band with the network for a short time is provided. It is an ATM switching network equipped with supporting means.

A feature of the present invention is that the subscriber exchange is provided with a plurality of routes which are set between the subscriber exchange as the originating side and the other subscriber exchanges as the destination side exchange. Means for collecting and recording new route information regarding the above information regardless of whether or not there is a connection request, and a means for selecting a route for the user on the basis of the recorded route information at the time of a connection request.

The applicant of the present application has filed a prior application (Japanese Patent Application No. 7-226746, which has not been published at the time of filing of the present application) relating to the same inventor as the present application, in which the request from the subscriber terminal is requested. On the basis of the above, the subscriber exchange refers to a device for adaptively limiting the band and setting a route for the subscriber terminal. The invention of the present application has no concept of limiting the bandwidth, and the present application sets the connection in response to the connection request from the subscriber terminal. It is possible to limit it. The present invention is different from the invention described in the above-mentioned prior application, although it is common in that the connection is made based on the route information.

Means for collecting the plurality of route information are:
The subscriber exchange on the originating side includes means for transmitting a cell for collecting the route information for each virtual path, and the relay exchange and the subscriber exchange include:
It is desirable to include means for mounting route information in the information area when the cell arrives and transmitting the route information according to the route information recorded in the destination area.

The route information is information about a virtual path relating to the transit exchange and the subscriber exchange, and the transmitting means preferably transmits the cell to the originating subscriber exchange.

It is desirable that the means for selecting the optimum route selects the route having the lowest free route band or the lowest available route band ratio among the routes having the free band which is equal to or more than the bandwidth required by the user among the plurality of routes.

As a result, the network resource can be effectively used by selecting the route with the least wasted empty band.

Alternatively, it is preferable that the means for selecting the optimum route selects the route having the largest use band or use band ratio among the routes having an empty band which is equal to or more than the band required by the user among the plurality of routes.

That is, when a new VC is set to a route in which another virtual channel (hereinafter referred to as VC) is already set, the band of the route is set to be almost completely filled by the setting of this new VC. As a result, it is possible to eliminate a route having a halfway empty band, so that network resources can be effectively used.

A center device is provided, the subscriber exchange and the relay exchange are provided with means for transmitting a cell carrying the route information addressed to the center device, and the route information is transmitted from the cell that has arrived at the center device. And a means for notifying the subscriber exchange of the contents collected by the reading and collecting means.

The means for sending out comprises a means for sending out cells each carrying route information including congestion information when congestion occurs in a virtual path involving the subscriber exchange or the transit exchange. You can also

As a result, the originating subscriber exchange can grasp the congestion information of each route and exclude the route in the congestion state when setting the route.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a conceptual diagram of an ATM communication network of the present invention. Figure 2 shows A as the originating subscriber exchange.
3 is a block diagram of a main part of the TM exchange 20. FIG. Figure 3 is R
It is a block diagram of M cell. 4 ATM exchange as a subscriber exchange in transit exchange and the call-4 _11, 4 _12, 4 _21,
FIG. 4 is a block diagram showing the main parts of 4 ₂₂ , 4 ₃₁ , and 40. FIG. 5 is a block diagram of the main part of the center device 6. FIG. 6 is a diagram showing the contents of the route performance table.

According to the present invention, ATM exchanges 20 and 40 as subscriber exchanges, and relay transmission lines 7 ₁₁ and 7 ₁₂ as physical transmission lines connecting the ATM exchanges 20 and 40 to each other are provided.
7 ₂₁ , 7 ₂₂ , 7 ₃₁ , 7 ₃₂ , 7 ₄₁ and an ATM exchange as an intermediate exchange inserted in the relay transmission lines 7 ₁₁ , 7 ₁₂ , 7 ₂₁ , 7 ₂₂ , 7 ₃₁ , 7 ₃₂ , 7 _41. 4 ₁₁ , 4 ₁₂ , 4 ₂₁ ,
4 ₂₂ and 4 _31, and ATM exchanges 20, 40, 4 ₁₁ ,
The VP is set between 4 ₁₂ , ₄₂₁ , 4 ₂₂ and 4 ₃₁ ,
The exchange 20 or 40 is an ATM communication network including a protocol controller 21 shown in FIG. 2 as a means for supporting a protocol in which the user terminal device 3 adaptively performs flow control with the ATM communication network 1.

Here, the feature of the present invention is that A
The TM switch 20 is a VP currently used bandwidth available information hop count (a number of relay switch stages) for a plurality of routes which are set between the subscriber switch as the originating side and another subscriber switch as the receiving side subscriber switch. ), And a route information collecting unit 22 as a means for collecting and recording new route information regardless of whether or not there is a connection request, and a means for selecting a route for the user based on the recorded route information when making a connection request. And the protocol controller 21 of.

ATM exchange 2 which is a subscriber exchange on the calling side
The route information collecting unit 22 of 0 includes an RM cell sending unit 23 as a unit for sending an RM cell for collecting the route information for each VP, and an ATM switch serving as a relay switch and a destination subscriber switch. 4 ₁₁ , 4 ₁₂ , 4 ₂₁ , 4
₂₂ , ₄₃₁ , 40 are route information mounting units shown in FIG. 4 as means for mounting route information in the information area when the cell arrives and transmitting according to the route information recorded in the destination area. 14 are provided.

Further, ATM switch 40,4 ₁₁ a called side local exchange and the transit exchange, 4 _12, 4 _21, 4 _22,
4 ₃₁ includes along a route information issued section 15 as a means for sending addressed the RM cell equipped with route information about the VP involved in the exchange to the calling side local exchange.

[0027] Alternatively, the center device 6 shown in FIG. 5 in the ATM communication network is provided, ATM switch 40,4 _11, 4
_12, 4 _21, 4 _22, 4 ₃₁ comprises a route information issued section 15 as a means for transmitting the cell equipped with the route information addressed to the center device 6, from the cells arriving to the center device 6 A route information collecting unit 60 as a means for reading and collecting route information, and the route information collecting unit 60.
It is also possible to provide a route information notifying section 61 as a means for notifying the contents of the above to the ATM exchange 20 which is the calling side subscriber exchange.

Further, the route information issuing unit 15 determines the AT
M switch _{40,4 11, 4 12, 4 21} , 4 22, 4 BECN _{to 31} congestion VP involved in the mounting of the route information including the congestion information when an error occurs (Backword Explicit Congest
Ion Notification) Means for sending each cell may be provided.

[0029]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIG.
The user terminal device 3 is an ATM communication network 1 as shown in FIG.
A cell based on a band change request and other various protocols is issued to the. The contents of this cell are immediately determined by the ATM switch 20 in which the subscriber is housed. In the protocol controller 21 of the ATM switch 20, the VCI
It has a route performance table 24 that manages the performance information of the passing routes of
For example, the bandwidth request from I and the contents of the route performance table 24 are compared, and transfer, bandwidth change, and the like are permitted.

FIG. 6 is a diagram showing the contents of the route performance table 24 according to the first embodiment of the present invention. An empty band, a currently used band, and the number of hops are recorded for each route to the ground A. In FIG. 1, as a method of collecting the route information, the RM cell shown in FIG. 3 is sent from the ATM exchange 20 which is the originating subscriber exchange and is returned by the ATM exchange 40 which is the destination subscriber exchange. FIG. 3 is a diagram showing the structure of the RM cell, which is composed of a destination area H and a message area M, and the message area M includes an AT.
Each passing through the M switch 40,4 _11, 4 _12, 4 _21, 4 _22, 4 _31, usage and empty band, cellulose slate other route information is loaded by the route information mounting section 14 shown in FIG. 4 . In the destination area H, transit information is written by the ATM exchange 20.

A call acceptance procedure in the first embodiment of the present invention will be described. ATM exchange 2 which is the originating subscriber exchange
There are n routes from 0 to the ATM switch 40 which is the destination subscriber switch. However, it is unknown whether or not there is a band necessary for communication. FIG. 7 is a flowchart showing the call acceptance procedure of the first embodiment of the present invention. The call admission procedure of the first embodiment of the present invention shown in FIG. 7 is the required bandwidth VMb / s.
Among the routes that satisfy the above condition, the route with the smallest empty band is used.

Requested bandwidth VMb / from the user terminal device 3
For s (S1), paying attention to the first route (K = 1) (S2), the empty route band of the route K is the required band VM.
It is determined whether or not b / s or more (S3). If the empty route bandwidth of the route K is not more than the required bandwidth VMb / s, the next route is examined (S6) within a range in which the value of K does not exceed n (the total number of routes) (S7). Is greater than or equal to the required bandwidth VMb / s, it is determined whether or not the empty route bandwidth of the route K is smaller than the empty bandwidths of other route candidates (S4). If the empty route bandwidth of the route K is larger than the empty bandwidths of other route candidates, the next route is examined (S6) within a range where the value of K does not exceed n (S6), but the empty route bandwidth of the route K is If it is smaller than the empty band of the route candidate, the route K is set as the designated route (S5).

As a result, the route can be selected as a so-called packing rule. Also, bandwidth can be acquired instantly. Moreover, since the relay node notifies the free band information and the like in advance, it does not require relatively real-time processing.

(Second Embodiment) A second embodiment of the present invention will be described with reference to FIG. FIG. 8 is a flow chart showing the call acceptance procedure of the second embodiment of the present invention. a procedure of selecting a route with the least empty route bandwidth ratio from the n route candidates, n
A procedure for selecting a route with the largest used bandwidth from among these route candidates, and a procedure for selecting a route with the maximum used bandwidth ratio from among n route candidates will be shown.

First, the procedure for selecting the route with the smallest free route bandwidth ratio from the n route candidates will be described.
Regarding the requested bandwidth VMb / s from the user terminal device 3 (S1), pay attention to the first route (K = 1) (S1).
2) It is determined whether or not the empty route band of the route K is equal to or more than the required band VMb / s (S3). If the empty root band of the root K is not more than the required band VMb / s, the value of K is n.
(S6) The next route is checked within a range not exceeding (total number of routes) (S7), but if the empty route bandwidth of the route K is equal to or more than the required bandwidth VMb / s, then (empty route bandwidth of the route K) / ( (Empty route band of route K + used band of route K) ≤ (empty route band of route candidate) / (empty route band of route candidate + used band of route candidate) ... (Equation 1) It is determined whether or not ( S4). If the route K does not satisfy the above equation, the next route is examined within a range in which the value of K does not exceed n (S6) (S7), but if the route K satisfies the equation 1, the route K is set as the designated route (S5). ..

Next, the procedure for selecting the route with the largest used bandwidth from the n route candidates will be described. Requested bandwidth VMb / s from the user terminal device 3 (S
1), paying attention to the first route (K = 1) (S2),
It is determined whether or not the empty root band of the root K is the required band VMb / s or more (S3). If the empty root band of the route K is not equal to or more than the required band VMb / s, the next route is checked within a range in which the value of K does not exceed n (S6) (S7), but the empty root band of the route K is the required band VMb / s. If s or more, it is determined whether or not (used band of route K + V) ≧ (used band of route candidate + V) (Equation 2) is satisfied (S4). If the route K does not satisfy the above equation, the next route is examined within a range in which the value of K does not exceed n (S6) (S7). If the route K satisfies the equation 2, the route K is set as the designated route (S5). .

Further, a procedure of selecting a route having the maximum used bandwidth ratio from the n route candidates will be described. Requested bandwidth VMb / s from the user terminal device 3 (S
1), paying attention to the first route (K = 1) (S2),
It is determined whether or not the empty root band of the root K is the required band VMb / s or more (S3). If the empty root band of the route K is not equal to or more than the required band VMb / s, the next route is checked within a range in which the value of K does not exceed n (S6) (S7), but the empty root band of the route K is the required band VMb / s. If s or more, (use bandwidth of route K + V) / (use empty bandwidth of route K + use bandwidth of route K) ≧ (use bandwidth of route candidate + V) / (use empty route bandwidth of route candidate + use of route candidate) Used band) (Equation 3) is determined (S4). If the route K does not satisfy the above equation, the next route is examined within a range in which the value of K does not exceed n (S6) (S7), but if the route K satisfies the equation 3, the route K is set as the designated route (S5). .

(Third Embodiment) A third embodiment of the present invention will be described with reference to FIG. FIG. 9 is a diagram showing a cyclic state of an RM cell according to the third embodiment of the present invention. ATM which is each relay exchange
The exchanges 4 ₁ to 4 ₃ or the AT which is the destination subscriber exchange
The M exchanges 40 ₁ and 40 ₂ periodically voluntarily make RMs.
The route performance is reported by sending cells to the ATM switches 20 ₁ and 20 ₂ which are the originating subscriber switches.

(Fourth Embodiment) A fourth embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a diagram showing the overall configuration of the fourth embodiment of the present invention and the transfer status of RM cells. The center device 6 grasps the traffic condition in the ATM communication network 1 and, based on the congestion node and other information, ATM exchanges 20 ₁ and 20 which are subscriber exchanges.
Give information to ₂ .

[0040] to the center device 6 shown in FIG. 5, the route information collection unit 60 for collecting information from the ATM exchange 4 _{1-4 3} is a transit exchange is provided, the ATM exchange 4 _1-4
Receive RM cells from ₃ and collect route information. The obtained route information is newly added to the message area M of the RM cell.
And transfer it to the ATM exchanges 20 ₁ and 20 ₂ which are the originating subscriber exchanges.

(Fifth Embodiment) In common with the first to fourth embodiments of the present invention, the operation of the originating-side subscriber exchange will be described with reference to FIG. FIG. 11 shows RM in SHM protocol.
It is a figure which shows the flow of a cell. To request bandwidth changes from the user terminal 3 _1, a calling-side subscriber exchange AT
In the M switch 20, the route performance table 24 of the route to which the VC belongs is indexed to see, for example, an empty band. This empty band is the link information and the like of the least empty band on the route. In the protocol controller 21,
Based on this usage rate, the remaining bandwidth and the like are estimated and the bandwidth is changed and other information is returned to the user terminal device 3.

As shown in FIG. 11, the user terminal device 3 ₁
Indicates "10" to the ATM exchange 20 which is a subscriber exchange.
A request for "Mb / s communication band" is sent.
Indexed route performance table 24 in the exchange 20 in the protocol controller 21, returns promptly answered by examining the root and its usage to the user terminal 3 _1. Therefore, from "request" to "O
The time up to K ″ can be shortened by using the present invention.

When congestion occurs on the route related to the ATM switch, the route information is transmitted by the cells carrying the route information including the congestion information. The route can be selected by grasping the information.

[0044]

As described above, according to the present invention,
A high-speed and flexible ATM communication network can be realized. AT
It is possible to simplify the hardware configuration of the M switch and instantly find the optimum route from a plurality of routes. It is possible to reduce the cell discard rate and realize an ATM communication network with high throughput.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of an ATM communication network of the present invention.

FIG. 2 is a block diagram of a main part of an ATM exchange as a calling side subscriber exchange.

FIG. 3 is a configuration diagram of an RM cell.

FIG. 4 is a block diagram of a main part of an ATM exchange as a relay exchange and a subscriber exchange on the receiving side.

FIG. 5 is a block diagram of a main part of the center device.

FIG. 6 is a diagram showing the contents of a route performance table.

FIG. 7 is a flowchart showing a call reception procedure according to the first embodiment of the present invention.

FIG. 8 is a flowchart showing a call reception procedure according to the second embodiment of the present invention.

FIG. 9 is a diagram showing a cyclic state of an RM cell according to the third embodiment of the present invention.

FIG. 10 is a diagram showing the overall configuration of a fourth embodiment of the present invention and the transfer status of RM cells.

FIG. 11 is a diagram showing a flow of RM cells in the SHM protocol.

FIG. 12 is a diagram showing a concept of an ATM communication network.

FIG. 13 is a diagram showing a timing chart of RM cell handling in each ATM switch.

FIG. 14 is a diagram showing a time response to a user request.

[Explanation of symbols]

1 ATM communication network 3, 3 ₁ , 3 ₂ user terminal device 4 ₁ to 4 ₄ , 4 ₁₁ , 4 ₁₂ , 4 ₂₁ , 4 ₂₂ , 4 ₃₁ , 20, 2
0 ₁ , 20 ₂ , 40, 40 ₁ , 40 ₂ ATM switch 6 Center device 7 _{1 to} 7 ₃ , 7 ₁₁ , 7 ₁₂ , 7 ₂₁ , 7 ₂₂ , 7 ₃₁ , 7 ₃₂ , 7
₄₁ Relay transmission line 14 Route information loading unit 15 Route information issuing unit 21 Protocol controller 22, 60 Route information collecting unit 23 RM cell sending unit 24 Route performance table 61 Route information notifying unit H Destination area M Message area

Claims (7)

[Claims] 1. A plurality of subscriber exchanges, a plurality of physical transmission lines that connect the plurality of subscriber exchanges to each other, and a relay exchange that is inserted into the plurality of physical transmission lines. In an ATM communication network in which a plurality of routes can be set between private branch exchanges, a subscriber exchange is set up between multiple subscriber exchanges that serve as the originating subscriber exchange and the receiving subscriber exchange. Means for collecting and recording new route information about the route regardless of whether or not there is a connection request, and means for selecting a route for the user based on the recorded route information when the connection request is made. Let A
TM communication network. 2. The means for collecting the route information includes means for transmitting a cell for collecting the route information for each route, and the relay exchange and the subscriber exchange exchange the information when the cell arrives. 2. The ATM communication network according to claim 1, further comprising means for mounting route information in the area and transmitting the cell according to the route information recorded in the destination area. 3. The route information is information about a virtual path relating to the transit exchange and the subscriber exchange, and the transmitting means transmits the cell to the originating subscriber exchange. The ATM communication network described. 4. The route selecting means selects a route having the least empty route band or an empty route band ratio among routes having an empty band equal to or more than a user requested band among the plurality of routes. 1. The ATM communication network described in 1. 5. The route selecting means selects a route having the largest use band or use band ratio among routes having an empty band equal to or more than a user requested band among the plurality of routes. ATM communication network. 6. A center device is provided, and the subscriber exchange and the transit exchange are provided with means for transmitting a cell carrying route information addressed to the center device, and the center device is provided with a route from this arrived cell. 2. The ATM communication network according to claim 1, further comprising means for reading and collecting information, and means for notifying the subscriber exchange of the contents collected by the means for reading and collecting. 7. The cell for transmitting the route information including the route information including the congestion information when the route for the subscriber exchange or the transit exchange causes congestion, respectively. ATM switch.