KR0146545B1 - Band width control and call admission method in the atm access network with ring structure - Google Patents

Abstract

The present invention relates to a bandwidth control and call admission control method in an ATM access network having a ring structure for analyzing traffic flow due to a ring characteristic to provide more efficient use of network resources and providing a reliable service. A first step of finding the least used segment in the virtual ring having the corresponding QoS when the request is made; Calculating a bandwidth in a forward / reverse direction by using a bandwidth occupied by the virtual ring in the found segment as a multiplexing function (m (x, y)); Determine if the forward bandwidth is '0', if not '0' to test the forward segment, if '0' to determine if the reverse bandwidth is '0' and if not '0' to test the reverse segment Step 3; If any of the segment tests fail, the call is rejected. If all succeeds, the fourth step is to accept the call by adjusting the bandwidth for all segments and virtual rings that were performed in the segment test and assigning the virtual path identifier and the virtual channel identifier to the call. It characterized in that it comprises a very effective management of the virtual path and the virtual ring of the appropriate bandwidth control enables very effective resource management.

Description

Bandwidth Control and Call Acceptance Method in ATM Access Network with Ring Structure

1 is a schematic configuration diagram of an access network having a general ring structure;

2 shows link usage by segment,

3 is an exemplary virtual ring configuration according to the present invention,

4 is a flowchart of call admission control processing according to the present invention;

* Explanation of symbols for main parts of the drawings

11: Ring node (RN) 12: Head node (HN)

The present invention analyzes the traffic flow due to the structural characteristics of a ring in an ATM (Asynchronous Transfer Mode) access network having a ring structure, and thus provides a more efficient use of network resources and a reliable access service in an ATM access network. Bandwidth control and call admission control method.

In general, ATM, which is a transmission method of a broadband communication network, has an advantage of flexibly accommodating various services. However, the fact that services of various traffic characteristics are multiplexed and transmitted means that it is difficult to predict traffic flow, and unexpected situations may occur frequently.

Therefore, the communication network performs traffic control such as network resource management, call / connection admission control, network / user parameter control, and priority control, thereby inherent quality of service such as cell loss or cell delay for network traffic. Quality of service (Grade of Service), such as call rejection rate, must be satisfied by a certain level.

In addition, the network needs a bandwidth allocation to effectively manage bandwidth in the network and bandwidth allocation capable of guaranteeing the QoS required by the service while obtaining statistical multiplexing gains.

The ATM access network serves as an interface to the subscribers as the entrance and exit of the ATM communication network. The main functions include cell aggregation and distribution functions and cell switching functions, and may have signal and call processing functions as necessary.

The access network as described above may be configured in various forms, and representative structures include a star structure, a bus structure, and a ring structure. The ring structure can be efficiently applied to an access network because of high bandwidth utilization, easy addition / deletion of nodes, and higher reliability than a bus structure.

FIG. 1 is a schematic diagram of an access network having a general ring structure, in which a plurality of ring nodes (RNs) that accept external subscribers multiplex / demultiplex traffic between a user interface and a ring interface. The virtual path multiplexer is connected in a ring form.

Head quarter node (HN) 12 is connected to a plurality of rings (rings # 1 to ring # 4) to which the plurality of ring nodes 11 are connected to switch traffic between an ATM switch and a ring node 11. It is a virtual channel switch.

As described above, an access network having a ring structure adds a cell to be transmitted after dropping a cell if each ring node is transmitted to itself by accessing the ring along with the rotation direction of the ring. Therefore, looking at the traffic flow in the ring, the receiving cell for the ring node gradually decreases and the transmitting cell of the ring node gradually increases in the rotation direction.

Therefore, a serious imbalance may occur between the bandwidths actually used in the ring node segments. In particular, this phenomenon is more severe when assuming that there is no internal call function in the access network.

Specifically, when the number of ring nodes is n, if a node and a segment number are numbered from 0 in the rotational direction of the ring from the head node, the head node becomes node 0, and the head node and the first ring node The segment becomes segment 0, and thus, the segment between node n and headno becomes segment n and the traffic in each segment is shown as follows.

Segment i (0 i n) traffic is

If i = 0,

if i = n,

Otherwise,

The traffic in the i-th segment is then composed of transmission traffic to the first ring node and received traffic from the (i + 1) th ring node to the last ring node.

FIG. 2 is a segmental link utilization, which shows a specific number of segmental bandwidth usage in an access network composed of one head node and four ring nodes, that is, five segments.

As shown in the figure, the bandwidth B for transmission gradually increases according to the rotational direction of the ring, and conversely, the bandwidth A required for reception gradually decreases.

Virtual paths, which are very important in terms of traffic control and network resource management, can simplify routing and call admission control, and can group traffic with similar characteristics into one virtual path to guarantee different QoS for each virtual path. And more statistical multiplexing effects can be expected.

However, if we accept four ring nodes and four subscribers per ring node, there will be at least 64 virtual paths in the ring. In this case, the bandwidth reservation for the virtual path has to be allocated too little bandwidth for each virtual path, and too much burden is generated on the virtual path reconfiguration due to periodic or network state changes. In addition, since each service may have a different forward bandwidth and a reverse rental bandwidth, in the case where transmission and reception occur on the same link such as a ring, bandwidth allocation per virtual path may cause serious waste.

Therefore, the present invention analyzes the traffic flow due to the structural characteristics of the ring as well as the characteristics of the information source, controls the bandwidth in units of segments between the nodes within the ring, and operates a virtual path to ensure efficient routing and quality of service. It is an object of the present invention to provide a bandwidth control and a call admission control method in an ATM access network for gain.

According to the present invention for achieving the above object, when a call requests a service with a forward quality of service (QoS), a reverse QoS, a forward bandwidth, a reverse bandwidth, and the like, the segment that is least used in the virtual ring having the corresponding QoS is selected. First step of finding: A method for calculating an appropriate bandwidth for the forward / reverse direction by using the bandwidth occupied by the virtual ring in the found segment in the multiplexing function (m (x, y)) and applying it to the forward / reverse bandwidth. Step 2; If the forward bandwidth is '0', the test is performed on the forward segment if it is not '0'. If the forward bandwidth is '0', the test is performed for the reverse segment if it is not '0'. Performing a third step; If any one of the segment tests fails, the call is rejected and all succeeds. The fourth step in which the call is accepted by adjusting the bandwidth for all segments and virtual rings that were performed in the segment test and assigning the virtual path identifier and the virtual channel identifier to the call Characterized in that it comprises a.

Hereinafter, with reference to the accompanying drawings will be described an embodiment according to the present invention;

In the present invention, the bandwidth in the ring is controlled in segments and the virtual paths are managed by QoS. The QoS is divided into the following four types and one virtual path is allocated to each QoS.

QoS 0: ATM Adaptive Layer (AAL) Type 1/2 Service

QoS 1: ATM Adaptive Layer (AAL) Type 3/4 Service

QoS 2: ATM Adaptive Layer (AAL) Type 5 Service

QoS 3: ATM Adaptive Layer (ALL) Type X Service

And undefined QoS classes

In addition, a virtual path preassigned for each subscriber is used in the ring to perform routing based on the ring node's virtual path. Therefore, routing from the head node to the ring node also uses only the virtual path identifier and thus does not require a separate routing mechanism. However, since one subscriber should be assigned at least as many virtual paths as the QoS, each ring node should have at least as many virtual paths as subscribers and the number of QoS classes. Too many virtual paths, so controlling each of them is another problem because the paths must be operated. Therefore, in the present invention, the virtual path is used only for routing, and traffic multiplexing is performed through a new concept of virtual ring.

3 is an exemplary diagram of a virtual ring configuration according to the present invention.

As shown in the figure, the virtual ring means the sum of the virtual channel bandwidths allocated to the virtual paths of the same QoS in the ring. That is, the virtual channel 0 has a QoS of 0, the virtual ring 1 has a QoS of 1, the virtual ring 2 has a QoS of 2, and the virtual ring 3 has a total of 3 virtual channel bandwidths in a virtual path. This also has a different occupied bandwidth for each segment.

Therefore, the virtual ring allocates bandwidth in consideration of the gain of statistical multiplexing, which can yield a larger gain when multiplexing more traffic. The multiplexing function m applied thereto is defined as follows.

where x is the bandwidth requested by the service, y is the bandwidth being used, and x 'is the bandwidth allocated to the service.

m (x, y) = x '= x for non-statistical multiplexing service

(x for mom-statistical multiplexing service)

m (x, y) -x'x for statistical multiplexing service

(x for statistical multiplexing service)

In this case, the larger the bandwidth y used, the smaller the actual allocated bandwidth x '.

4 is a flow diagram of a call admission control process according to the present invention, when a call requests a service with a forward QoS, a reverse QoS, a forward bandwidth, a reverse bandwidth, and the like as a parameter (41), the least used in the virtual ring having the QoS. By finding a segment 42, the bandwidth occupied by the virtual ring in the segment is used for the multiplexing function and then applied to the forward / reverse bandwidth to calculate an appropriate bandwidth for the forward / reverse direction (43).

That is, the proper bandwidth determination to allocate to the call for the forward and reverse bandwidth requested by the call is performed by the multiplexing function, where in the multiplexing function m (x, y) x is the bandwidth requested by the call and y is the virtual with the QoS requested by the call. This is the bandwidth used by the segment using the least bandwidth in the ring.

After calculating the bandwidth, it is determined whether the forward bandwidth is '0' (44). If it is '0', it is determined whether the reverse bandwidth is '0' and if it is not '0', the forward segment test is performed (45). If it is '0' (46) and if it fails, the call rejection is performed (51). If the value for the reverse bandwidth is '0', adjust the bandwidth for the segment and the virtual ring (48), if not '0', test for the reverse segment (47) and if it succeeds, adjust the bandwidth for the segment and the virtual ring. If it fails, it performs call rejection (51).

This segment test determines whether or not the bandwidth determined previously exists for every segment on the path through which the call passes. Therefore, if any one of the segment tests fails, the call is rejected (51), and if successful, the bandwidth is adjusted for all segments and virtual rings that were performed in the segment test (48).

When the bandwidth adjustment for the segment and the virtual ring is completed, the virtual path identifier and the virtual channel identifier are allocated to the call (49), and the call is accepted (50).

According to the above, the present invention enables highly effective resource management by appropriate bandwidth control and operation of virtual paths and virtual rings in consideration of the flow of traffic that is significantly affected by not only the traffic characteristics of the information source but also the configuration of the network.

Claims (5)

Finding a segment that is least used in a virtual ring having a corresponding QoS when the call requests a service with a forward quality of service (QoS), a backward QoS, a forward bandwidth, a backward bandwidth, etc. as a parameter; Calculating a bandwidth for the forward / reverse direction by using the bandwidth occupied by the virtual ring in the found segment in a multiplexing function (m (x, y)) and applying it to the forward / reverse bandwidth; Determine if the forward bandwidth is '0', if not '0' to test the forward segment, if '0' to determine if the reverse bandwidth is '0' and if not '0' to test the reverse segment Step 3; If any one of the segment tests fails, the call is rejected. If all succeeds, the fourth step is to accept the call by adjusting the bandwidth for all segments and virtual rings that were performed in the segment test and assigning the virtual path identifier and the virtual channel identifier to the call. Bandwidth control and call acceptance method in an Asynchronous Transfer Mode (ATM) access network having a ring structure, comprising: a. 2. The system of claim 1, wherein the QoS comprises: a first QoS of an ATM adaptation layer (AAL) type 1/2 service; Second QoS of ATM Adaptation Layer (AAL) Type 3/4 service; Third QoS of ATM Adaptation Layer (AAL) Type 5 service; Bandwidth control and call admission method in an ATM access network having a ring structure, characterized by being divided into ATM adaptive layer (ALL) type X services and fourth QoS of undefined QoS class. 3. The ATM of claim 2, wherein each QoS is assigned one virtual path so that traffic multiplexing of similar characteristics and routing between the head node and the ring node occur using only the virtual path identifier. Bandwidth Control and Call Admission in Access Networks. The method of claim 1, wherein the virtual ring is a sum of virtual channel bandwidths allocated to virtual paths of the same QoS in a ring. The multiplexing function (m (x, y)) of claim 2, wherein the multiplexing function (m (x, y)) of the second step is multiplexing when x denotes a bandwidth requested by the service, a bandwidth in use by y, and a bandwidth in which x 'is allocated to the service. Function (m (x, y)) = x '= x for mom-statistical multiplexing service, multiplexing function (m (x, y)) = x'x (for statistical multiplexing service Bandwidth control and call admission method in an ATM access network having a ring structure, characterized in that x for statistical multiplexing service).