KR100238436B1 - Composite banyan network architecture and creation method of routing tag using network symmetry - Google Patents

Abstract

The present invention relates to a method for generating a path tag of a cell using a synthetic banyan network structure and a network symmetry providing a multipath multistage connection, and a novel multipath that solves the complexity of implementation and the cell loss rate in the design of a space-switched switched network. We propose a synthetic banyan network (CBN) structure that is a multi-stage network, a method and a conversion method for generating a priority path tag and a selective path tag used for the assignment of magnetic paths in the proposed synthetic banyan network. Proposed method and conversion method for generating priority path tag and selective path tag used for allocation of magnetic paths in the ATM system, it is possible to design the magnetic path control for high-speed switching while guaranteeing high connectivity by increasing hardware complexity in ATM network design. New base networks to support, and the multiple paths that these base networks provide By the generation and conversion process of path labels that can be used as this has the effect of enabling the high connectivity and fast switching.

Description

A method for generating cell path tags using synthetic banyan network structure and network symmetry

The present invention relates to a method for generating a path tag of a cell using a synthetic banyan network structure and a network symmetry providing a multipath multi-stage connection.

In the conventional space division type asynchronous transfer mode (hereinafter referred to as ATM) switching network structure, the space division type switching network has a cross-bar switch and a banyan based switch according to a method of providing a path. , And N ² There are three main categories: disjoint path switch.

With the crossbar switch N ² Dismantling path switches are basically used to provide a path. N ² Since there are two switching elements (hereinafter referred to as SE), the size of the switch is limited.

In contrast, an exchange structure based on a banyan network can be implemented with less hardware, and self-routing is performed in each switch element (hereinafter referred to as SE) constituting the exchange. There are no restrictions on the size or speed of exchanges that can be implemented using.

However, since the existing banyan network is a single-path switching network and corresponds to a blocking switching network, the yield obtained in the banyan network is limited to a low level due to the discomfort in the banyan network.

Many studies have been made to improve such low yields, and the results can be classified into five categories as follows.

First, the buffered banyan network (hereinafter referred to as BBN) is basically an attempt to solve the insufficient connectivity of the banyan network through a buffer added to the input of each SE.

When two cells in each SE compete for one path, the cell that has won the competition occupies the path, and the cell lost in the competition is stored in a buffer to obtain a path selection opportunity in the next time slot. The BBN also has a limitation in improving the yield by increasing the buffer.

Sorted Banyan Network (hereinafter referred to as SBN) allows the cells that arrive at the exchanger to first pass through a batcher sorting network so that the sorted Banyan Network can be routed without internal discomfort. The traffic pattern is obtained and passed through the banyan network.

Representative examples of this approach are the Starlite switch and the Sunshine switch.

However, in order to implement the above scheme, it is necessary to simultaneously implement an alignment network and a recycling mechanism.

Distributed Banyan Network (hereinafter referred to as DBN) is a distributor based on reverse Banyan network at each stage in order to add a buffer to each SE and maximize the effect of the buffer like the buffered Banyan Network. ).

A distributor based on reverse banyan network allows sharing of buffers of SEs belonging to each stage.

It is known that the efficient distribution of traffic by the distributor allows the DBN to achieve the desired performance using only a small amount of buffers.

Representative examples thereof include a D_logic switch, a helical switch, and a multinet switch.

This method can be implemented with a small amount of buffer because the buffer sharing effect is high at the stage close to the input stage.

In addition, in order to handle the traffic of ATM clustering, it is necessary to increase the internal speed or to double the amount of hardware.

Layered Banyan Network (hereinafter referred to as LBN) horizontally distributes several Banyan networks with limited connectivity and distributes an appropriate amount of traffic to each Banyan Network.

There is also a concentrator and an output buffer at the output stage that focus cells from the same output stage of each banyan network to one port.

Representative examples implemented in this manner include a parallel banyan network, a new parallel banyan network, and a pipeline banyan network.

This method has a disadvantage in that the cell loss rate is high, so that it is necessary to connect the exchange elements in the same position in the horizontal banyan network.

The Extended Banyan Network (hereinafter referred to as EBN) is primarily used to pull out cells that have found the right path out of the cells that have passed through the Banyan Network, and to give new paths to the cells that do not find the path. It is made by repeating a network that is topologically identical to Banyan or Banyan.

Cells that do not get the desired path in the first network or stage have a new routing opportunity in the next network or stage.

Switching networks created in this way include tandem banyan networks, rerouting networks, shuffleout networks, dual shuffle networks, and bridge shuffle networks. Etc. The tandem banyan network has a disadvantage of requiring a larger buffer as the size of the network increases.

In addition, even in the change network, since each SE must have a buffer, the implementation of a very large integrated circuit (VLSI) is complicated and the control mechanism is complicated.

In order to solve the above disadvantages, the present invention proposes a structure of a synthetic banyan network, which is a multipath multistage network, as a basic network for optimizing a space partitioned switching network, and provides a method of generating and converting a path tag for ultra-fast switching in the proposed network. It aims to do it.

In order to construct a large-capacity partitioned switching network, it is necessary to maintain a high level of connectivity while maintaining a certain level of hardware and control complexity.

In the present invention is typically used in the space-switched switching network N ² As an alternative to overcome the high hardware complexity of the decommissioning path switch and the low connectivity of the banyan network, the self-routing method is a high-speed path providing method for efficiently utilizing the multipath and the structure of the synthetic banyan network, which is a multipath multistage network. Provides a way to create and convert selection path tags for selection.

1 is a multi-path structure diagram between the basic structure and the input / output line of the synthetic banyan network to which the present invention is applied,

2 is a structural diagram of a conversion table of a selection path tag of a synthetic banyan network;

3 is a flowchart illustrating a method for generating a selection path tag using a conversion table in a path selection method according to the present invention;

4 is a flowchart illustrating a method for generating a selection path tag without using a conversion table in the path selection method according to the present invention.

In order to achieve the above object, the present invention synthesizes a banyan network and a reverse banyan network into a single network to provide two or more completely separate multipaths between each input / output line, and the connection structure between each end includes a banyan network and a reverse banyan network. It is characterized by expressing by simple phase description function by synthesizing.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a multi-path structure diagram between the basic structure and the input / output line of the synthetic banyan network to which the present invention is applied, the composite banyan network (hereinafter referred to as CBN) is a sheet of banyan and reverse banyan network It is a multipath multi-stage network that combines and provides two or more completely separate multipaths between input / output lines.

The synthetic banyan network, which is a kind of the spatially divided switching network of FIG. 1, has a high connectivity that provides one or two selection paths at each end, compared to a banyan network providing only a single path between each input / output line. O (N ² ) With hardware complexity of N ² Disassembly path switch and crossbar network are almost same as banyan network O (NlogN) Has a hardware complexity of.

Since the synthetic banyan network has three input / output lines, a binary signed digit number system must be introduced to represent the connection between the stages.

The binary code bit number system is { } Represents numbers based on digits.

The connection structure of each stage is composed of the synthesis of banyan network and inverse banyan network, which can be described simply through simple topology-describing function.

K _i To i Binary number representing the phase of the switching element in the first stage, K _{i + 1} To i + 1 However, if the binary number and the equal sign (=) representing the phase of the switching element are the symbols representing the connection between the two, the connection structure of the synthetic banyan network can be expressed as follows.

here n Is the number of stages in the switching network, and denotes an exclusive-or operation.

1 is a multi-path structure diagram between the basic structure and the input / output line of the synthetic banyan network to which the present invention is applied, the characteristic of the synthetic banyan network is a switching network consisting of 3x3 switching elements, the left and right relative to the center of the switching network It is a fully symmetrical structure.

This complete symmetry, unlike banyan networks, is an important reason for providing multiple paths in synthetic banyan networks.

Link structures that are symmetrical in the connection structure of synthetic banyan network are called symmetrical link structures (Pair Links) and has the advantage of facilitating the conversion of routing tags to provide multiple paths.

1 is an example of a 16 × 16 synthetic banyan network consisting of four stages, the connection structure shown by the thick line is the connection structure of the existing banyan network, the connection structure represented by the thin line is the connection structure of the reverse banyan network.

Banyan network is a switching network with minimal hardware complexity that provides a single path between N inputs and N outputs.

When the banyan network hardware complexity and number of paths are set to 1, the synthesized banyan network hardware complexity increases to 9/4 = 2.25 and the average number of paths is averaged over (3 + 3 *) 2) /4=2.25, so 2.25 * (logN) / 2.

Therefore, if the ratio of the average number of paths of the banyan network and the hardware complexity is 1, then the synthetic banyan network is (logN) / 2.

If two paths are obtained using two single path networks, the hardware complexity is 2, the number of paths is also 2, and the ratio of the average number of paths and the hardware complexity is 1.

Therefore, the method of obtaining multipath using synthetic banyan can increase the ratio of the number of paths to the hardware complexity, and the hardware that should be used to guarantee the same number of paths, rather than the method of obtaining multiple paths using multiple banyan networks. Complexity can be reduced.

3 is a flowchart of a method for generating a selection path tag using a conversion table in the path selection method according to the present invention, wherein the synthetic banyan network is a path for processing path assignment of cells introduced into a switching network by a self routing method. Use a routing tag. Cells arriving at the input end of the switching network are assigned a primary routing tag (S1), which represents the logical distance between the input and output ends, representing the logical distance between the input and output ends of the switching network. -or) is calculated by the operation (S2).

After determining the logical distance between the input terminal and the output terminal as an exclusive logical sum, it is determined whether the tension is generated (S3), and when it occurs, it is moved to the next stage (S4), and if it is not generated, it is determined whether the modified path tag is required ( S5).

If cells that have been assigned a priority path tag require a modified path due to competition between cells in the middle of searching for a path, a new alternative routing tag is assigned (S6, S7). It is possible to convert only two bits in the tag, and the rules of the conversion follow the conversion table of FIG.

As shown in FIG. 2, the synthetic banyan network is composed of a banyan network and a reverse banyan network, and has three connection lines for each SE.

로 표시되는 역반얀망에 해당하는 사선과 0 으로 표시되는 두망이 공유하는 수평선에 해당된다. i 번째 stage에서, 반얀망에 해당되는 사선은 2ⁱ 의 논리적인 목적지와의 거리를 줄일 수 있고, 역반얀망에 해당되는 사선은 2^logN-i-1 의 논리적인 목적지와의 거리를 줄일 수 있다.These three connecting lines One Diagonal lines corresponding to the banyan network, denoted by

The diagonal line corresponding to the reverse banyan network represented by 0 The two networks represented by are the horizontal lines shared. i In the second stage, the banyan line 2 ⁱ Distance from the logical destination of the 2 ^{log N-i-1} Can reduce the distance to the logical destination.

Cells entering the synthetic banyan network are initially connected to the banyan network by the priority path tag. {0,1} Is assigned to the path.

을 경로로 택한다는 것을 의미한다.The deflection of these cells is the connection line of reverse banyan network.

Means to take the path.

i In the first step, if the connection line corresponding to reverse banyan network is selected as the path 2 ^{log N-i-1} Since we reduced the logical distance of 2 ⁱ To reduce the logical distance of logN-i-1 In the second stage, the connection line corresponding to the reverse banyan network should be selected as the path. The case where the reflected bit (s) of the priority path table in the conversion table is 00 is a special case where the corresponding logical distance is zero.

에 해당하는 연결선을 선택하여 2ⁱ 의 논리적인 격차를 제거해야 한다.in this case, i At the first stage One Is biased into 2 ⁱ Because of the logical distance gap of logN-i-1 In the first column

Select the connecting line for 2 ⁱ It should eliminate the logical gap.

에 해당하는 연결선을 선택했다면 위와같은 이유로 logN-i-1 번째 단에서 1 에 해당하는 연결선을 선택해야 한다.Contrary, i At the first stage

If you have selected the corresponding connection line for logN-i-1 In the first column One The connection line corresponding to the

The conversion table is a summary of these logical processes as a combination of path tags.

4 is a flowchart of a method for generating a selection path tag table without using a conversion table in the path selection method according to the present invention. The conversion by the conversion table requires a process of finding and reading the contents of the table every time a conversion is required. Not desirable for

In FIG. 4, instead of using a conversion table to implement high-speed switching in the switching network, a bit-wise operation including only bits of a priority path tag corresponding to a stage where a cell collision occurs and information on a newly selected path is performed. In this paper, we propose a way to create a path tag.

In FIG. 4, cells arriving at the input terminal of the switching network are assigned a priority path tag (S8), which represents a logical distance between the input terminal and the output terminal, and is obtained by an exclusive OR operation. (S9).

After calculating the logical distance between the input terminal and the output terminal by an exclusive OR operation, it is determined whether the tension is generated (S10). If it does not occur, the next step is moved (S11). (S12).

In order to implement high-speed switching in the switching network, a selection path tag is generated by a bit-wise operation including only bits of a priority path tag corresponding to a cell collision stage and information on a newly selected path (S13 and S14).

In the priority path tag, select the bit corresponding to the connection structure where the cell collision occurred. P ₁ , The bit corresponding to the symmetric structure P ₂ , The newly selected route C If you say P ₁ P ₂ Selection path to be replaced by A ₁ A ₂ Is obtained as follows.

here ∨ Denotes an OR operator, and the operation is as follows.

Under the above definition, for each case in the synthetic banyan network path selection tag conversion table of FIG. 2, the bit method and operation (all of the reflected bit (s) of the priority path tag and the bit (s) reflected in the selection path tag) are used. bit-wise or-operation) is zero in all cases.

이면

이 된다.For example, the reflected bit (s) of the preferred path tag 10 And the bit (s) reflected in the selection path tag

Back side

Becomes

This is sufficiently predictable even in the fact that the logical distance by the priority path tag and the logical distance by the selection path tag are the same.

The tag generation method which is not based on the conversion table uses this fact.

3 bits already known P ₁ , P ₂ , A ₁ (= C) And OR operation 0 Being A ₂ Calculate the value to get the path tag you want.

이 된다.therefore (P ₁ ∨P ₂ ∨C) ∨A ₂ = 0 To satisfy A ₂ Is

Becomes

As described above, the present invention can efficiently utilize a new basic network that supports the self-path control for high-speed switching while providing high connectivity with only a little hardware complexity when designing an ATM switching network, and efficiently use the multipath provided by the basic network. By using a method of generating and converting path tags, high connectivity and high speed switching can be achieved.

Claims (4)

In the synthetic banyan network, which is a multipath multi-stage network, for the optimization of space division type switching network, Combining Banyan and Inverse Banyan networks into a single network to provide two or more completely separate multipaths between each I / O line, Synthetic banyan network structure, characterized by expressing the connection structure between each end banyan network and inverse banyan network with a simple phase description function. A method of generating a path tag of a cell using the symmetry of a synthetic banyan network providing a multipath multistage connection, A first step of generating a selection path tag using a conversion table in a path selection method; A method of generating a path tag of a cell using the symmetry of a synthetic banyan network, comprising the second step of generating a selection path tag without using a conversion table in the path selection method. The method of claim 2, wherein the first process is A first step in which cells arriving at an input terminal of the switching network are assigned a priority path tag; A second step of expressing a logical distance between an input terminal and an output terminal to obtain an exclusive logical sum operation of numbers assigned from the top to the bottom of the input / output terminal of the switching network (S2); Obtaining a logical distance between the input terminal and the output terminal as an exclusive logical sum and determining whether a tension is generated (S3) and moving to the next stage if it occurs (S4); A fourth step of determining whether a modified path tag is required if no tension is generated after the determination (S5); The symmetry of the synthetic banyan network is characterized in that it consists of a fifth step of newly assigning a selection path tag when the cells assigned the priority path tag require a modified path due to competition between cells in the middle of searching for a path. Path tag generation method using the cell. The method of claim 2, wherein the second process Cells arriving at an input terminal of the switching network are assigned a priority path tag representing a logical distance between the input terminal and the output terminal (S8); A second step of obtaining an exclusive logical sum operation of numbers assigned from the top to the bottom of the input / output terminal of the switching network after receiving a priority path tag representing the logical distance between the input terminal and the output terminal (S9); Obtaining a logical distance between the input terminal and the output terminal using an exclusive OR operation and determining whether a tension is generated (S10); A fourth step of confirming whether a modified route tag is required if a tension occurs after the determination; If the modified path tag is required after the confirmation, the selection path tag is performed by the bit-wise operation consisting of bits of the priority path tag corresponding to the stage where the cell collision occurs and information about the newly selected path to implement high-speed switching in the switching network. Method for generating a path tag of the cell using the symmetry of the synthetic banyan network, characterized in that the fifth step of generating a.

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