CN1169325C - Explicit Priority Cell Relay Method and Communication Implementation System - Google Patents

Abstract

The present invention relates to an explicit priority method for information cell repeat and a communication system thereof, which belongs to network transmission technology adopting fixed length information cells. When an information cell sending end adopting the technology makes and sends the information cells, the information cells are set into different information cell transmission priorities according to specific information contents carried by each information cell. A network terminal of the inlet of a network monitors the information cell arrival rate of the communication virtual connection and discards the priorities of the information cells which arrive the information cell arrangement. The switching nodes of the network use preserved network resource for transmitting the information cells in a network contract, residual network resource transmits information cells outside the contract bandwidth. The present invention can mark a plurality of different information cell transmission priorities in a connection, indication for default flowing quality is used for simultaneously compromising benefits of users and the network, and an ensuring type service and a non ensuring type service simultaneously support in one connection. The priority type network transmission of user data is completed by the mutual match of information cell terminals, network terminals and switching nodes, and the present invention is suitable for the transmission of combined service.

Description

Explicit Priority Cell Relay Method and Communication Implementation System

technical field

The invention belongs to a network transmission method and its realization system, in particular to a packet network transmission method and a communication network system using fixed-length cells as information transmission units.

Background technique

The Broadband Integrated Services Digital Network (BISDN) proposed by ITU-T (International Telecommunication Union Standardization Sector) is a representative of such a packet transmission network. BISDN is a high-speed, low-latency multiplexing and switching network that uses Asynchronous Transfer Mode (ATM) to provide residential and business users with a wide range of integrated services through a standard user network interface, while supporting voice, data and video applications. and other types of transmission applications.

The ATM transmission network provides functions up to the ATM protocol layer. These functions are realized through the letter header. When transmitting information, only the letter header is operated without processing the content of the information field (payload). ATM only provides limited error detection operation through the letter header, and does not provide feedback retransmission. This layered processing principle simplifies the network processing of ATM, which is necessary for improving the scale expansion capability of the network. However, the current hierarchical division is too simple. After the terminal processing capability is improved, the network appears to be insufficient in transmission quality control, resulting in some insurmountable problems.

ATM assigns priority on the basis of connection, and it assigns priority to each virtual connection (VC) through signaling negotiation when calling out. The advantage of this implicit priority is that any type of priority can be defined as needed, and the number of priorities can also be adjusted as needed. But this also means that all cells of the same virtual connection have the same priority. Since the ISDN implicitly assumes that during the continuation of a communication connection, a communication terminal corresponds to only one service of a user, or a terminal (sometimes mixed with a terminal user) has a virtual application for each application at the same time. connect. Under this premise, this connection-based priority assignment method is feasible.

However, with the improvement of terminal performance, one terminal no longer corresponds to one user. Information about multiple sessions of multiple users may need to be transmitted on a virtual connection established between two terminals, and the transmission requirements of the same application session will also change during the communication process. At this time, it is difficult to reflect the special needs of different sessions of different users at different times by only one universal service quality parameter about the connection, and the transmission priority level should be specified for each cell.

The internetwork protocol (IP) sets 8-bit priority flags in the transmission frame format, but no reliable method for implementing these priorities has been proposed. At present, two IP priority schemes, integrated service priority and differential service priority, are proposed. Both of them are prioritized by the network according to the type of service, and when the network resources are insufficient, the service with a low priority will be discarded with a greater probability. Bag. The difference is that the integrated service priority scheme uses the resource reservation protocol, and the resource reservation is for each service flow; while the differentiated service priority scheme first aggregates services with similar requirements in the same subnet into one category, and then for each The business class performs resource allocation. None of them deals with the prioritization of different packets assigned by sources in the same traffic flow.

Since the congestion in the packet network is unavoidable, if the priority cannot be assigned by the source, then when the network is congested,

Since the congestion in the packet network is unavoidable, if the priority cannot be specified by the source, then when the network is congested, the network is likely to keep relatively minor data in the same connection, but discard relatively important data. Quality-graded coding techniques have been developed, which can dynamically change the source coding rate according to the channel bandwidth, or choose to discard lower-priority coded data during congestion, while maintaining acceptable quality of service. When the channel bandwidth is sufficient, transmitting all encoded data can improve the quality of service. Obviously, if the relative priority of cells in a virtual connection cannot be specified by the source, this hierarchical coding transmission scheme cannot be supported.

Contents of the invention

The purpose of the present invention is to provide a simple and easy-to-implement cell relay method and implementation system that supports multi-priority in connection, takes into account the interests of users and networks, is suitable for various types of services.

The present invention is characterized in that: when generating and sending cells, the sending end of the source of information sets the cells as different cell transmission priorities according to the specific information content carried by each cell; the network terminal at the network entrance monitors the communication The effective cell arrival rate of the virtual connection, set the cell discarding priority for the arriving cells; the network switching node uses the reserved network resources to transmit cells within the bandwidth of the service contract, and uses the remaining network resources to transmit the contract according to the cell priority Cells outside the bandwidth. The cell transmission priority set by the source includes at least three indicators of whether to send immediately, transmission delay level and transmission reliability, using urgent transmission indication, delay sensitive indication and important The data indication means that the cell discarding priority set by the network terminal is related to the effective cell arrival rate, and is represented by the traffic default indication in the cell payload type field. The network terminal at the network entrance monitors the effective cell arrival rate of the communication virtual connection, sets a lower cell discarding priority for cells within the service contract bandwidth, and sets the cell transmission priority for overspeed traffic exceeding the service contract bandwidth The order from low to high screens out traffic and marks it as a higher cell drop priority. When the network is congested, the switching node first discards cells with lower transmission priority, and then discards cells with higher transmission priority. The reserved network resources only include the minimum value of the requested bandwidth. Include connection identification field (21), payload type field (22), other control fields (23) and effective user data (24) in described information element; Wherein payload type field (22) includes emergency transmission instruction ( 221), delay sensitive indication (222), important data indication (223), traffic violation indication (224) and other flags (225), the communication terminal (11) sets the virtual connection identification number assigned by the network terminal in the signal The connection identification field (21) in the header, and the valid data of the user are encapsulated in the payload part (24) of the cell.

Therefore, the cell relay method of the present invention is: according to the quality of service requirements of communication transmission, establishing a communication virtual connection through signaling negotiation, and reserving necessary network resources. When generating and sending cells, the sending end of the information source sets the cells as different cell transmission priorities according to the specific information content carried by each cell. The network terminal at the network entrance monitors the effective cell arrival rate of the communication virtual connection, and sets the cell discarding priority for the arriving cells. The network switching node uses the reserved network resources to transmit cells within the service contract bandwidth, and uses the remaining network resources to transmit cells outside the contract bandwidth according to cell priority.

The improved method of the present invention is that, according to the service quality requirements of communication transmission, the communication virtual connection is established through signaling negotiation to reserve necessary network resources, and the bandwidth resources reserved by the network only include the minimum value of the applied bandwidth. When generating and sending cells, the sending end of the information source sets the cells as different cell transmission priorities according to the specific information content carried by each cell. The network terminal at the network entrance monitors the effective cell arrival rate of the communication virtual connection, and sets a lower filtering and splitting for the cells within the bandwidth of the service contract to be marked as a higher cell discarding priority. The network switching node uses the reserved network resources to transmit cells with the lowest cell discarding priority, and uses the remaining network resources to transmit the remaining cells according to the priority of cell transmission.

The further improved method of the present invention is that the cell transmission priority set by the above-mentioned information source includes at least three indicators of whether to send immediately, transmission delay level and transmission reliability, and uses the urgent transmission indication in the cell payload type field, The delay sensitive indication and the important data indication indicate that the cell discarding priority set by the network terminal is related to the effective cell arrival rate, which is indicated by the traffic default indication in the cell payload type field. When the network is congested, the switching node discards cells with lower transmission priority first, and then discards cells with higher transmission priority.

The realization system of the present invention is characterized in that: it contains user terminal, network terminal and switching node three parts, and described network terminal 12,14 is connected with switching node 13 respectively, and user terminal 11,15 is connected with network terminal 12,14 respectively connected. Wherein the user terminal contains the line driver interface 115, 155 which is connected with the network terminal so as to send the line transmission signal converted from the cell data to the network terminal, and restore the line transmission signal to receive the cell data in the opposite direction, and the line driver interface 115, 155 Interfaces 115, 155 are bidirectionally interactively connected to maintain the cell buffer queues for sending and receiving, and the transmission quality control modules 114, 154 that check whether cell discarding occurs, encapsulate the generated communication data into cells and simultaneously The transmission quality requires that the cell generation and priority setting modules 112, 152 sent to the transmission quality control modules 114, 154 after the cells are set to different transmission priorities, and the transmission quality control modules 114, 154 send The cell data extraction module 113, 153 that takes out the data required by the terminal application 111, 151 from the correctly received cell, and receives the data sent by the cell data extraction module 113, 153 and sends it to the cell generation and priority setting module 112, 152 Terminal applications 111, 151 that send communication data; Terminal applications 111, 151 in user terminals generate and consume communication data. The network terminal 12 contains the effective cell arrival rate measuring part 121 of monitoring the flow state of each connection from the direction of the user terminal, receives and buffers the cell buffer queue 122 of the cell sent from the direction of the user end, according to the arrival rate measurement part The measurement result of 121 and the connection parameter information pre-stored in the database unit 124 determine whether the effective cell arrival rate exceeds the smart control part 123 of the contract, store the database unit 124 of the connection parameter information, according to the instructions of the smart control part 123, send information to the slave user After the cell received by the terminal sets the cell discarding priority, the received cell is sent to the connected network switching node 13. The cell discarding priority changing part 125 is connected with the user terminal and the switching node, receives and switches The node sends incoming cells and forwards them to the user terminal's incoming cell filtering and distribution component 126 by address. The network terminal 14 has the same structure as the network terminal 12 . The network switch node 13 includes an input and output port module 131 , a switch matrix module 132 and an intelligent priority cell buffer module 133 . The network switching node 13 discards the cell according to the relative priority of the cell.

The advantages of the present invention are:

1. Support multiple priorities within a connection:

The present invention sets the relative priority indicator flags of cell transmission such as urgent transmission indication 221, delay sensitive indication 222 and important data indication 223 in the header payload type field 22, and the information source can be in a A number of different cell transmission priorities are identified in the connection. In this way, when the network is congested and the network switching node 13 has to discard cells, it can preferentially discard cells with lower transmission priority, so that cell discarding has the least impact on user communication quality.

2. Taking into account the interests of users and the network at the same time:

In the present invention, a flow violation indication 224 is also set in the payload type field 22 at the same time, as a cell relative priority indication controlled by the network. The network terminals 12 and 14 at the entrance of the network monitor the arrival flow of effective cells, and set the flow violation indication flag to be effective for the overspeed cells that violate the quality of service contract of the connection. The cell relative priority indicator controlled by the source and the cell relative priority flag controlled by the network in the payload type field 22 together reflect the relative priority of cells in the same communication virtual connection. Based on this, the network switching node 13 makes a decision on whether to forward or discard the cell, while taking into account the interests of the user and the network.

3. Suitable for a variety of business types:

Using the cell transmission priority setting method of the present invention, the user only needs to set the data cell that needs to be protected as a higher priority, and the data cell that needs to be transmitted as best as possible is set as a lower priority, and then the user can communicate on the same line. They are transmitted in the virtual connection at the same time, and a virtual connection is used to support guaranteed services and non-guaranteed services at the same time. In this way, there is no need to classify service types when establishing a connection, that is, the same connection method is used to support multiple service types, thus simplifying the complexity of the application software.

4. Ease of implementation:

The present invention divides the complex transmission priority management into three relatively independent and mutually cooperative parts: source end, network entrance and switching node, and each part completes certain and relatively simple functions. The information source only needs to set the relative priority of the cell related to the user's request, the network entrance only needs to determine whether the arriving cell is a breach of contract and set the relative priority of the relevant cell, and the network switching node 13 only needs to set the relative priority of the cell according to the relative priority of the cell. The high and low dropped cells. Through the organic cooperation among the three, the network transmission of user data is completed in the priority mode, and on the premise of ensuring the service quality of the contract-abiding cells, the best-effort transmission of default cells is realized according to the priority.

Description of drawings

Fig. 1 is a schematic structural diagram of the communication network system of the present invention.

Fig. 2 is a schematic diagram of the cell structure of the present invention.

Fig. 3 is a diagram of the relationship between the internal implementation structure and the external bidirectional flow of the input buffer type network terminal of the present invention.

Fig. 4 is a structural block diagram of the second implementation method of the network terminal of the present invention.

Fig. 5 is a structural block diagram of the third implementation method of the network terminal of the present invention.

Fig. 6 is a structural block diagram of the output buffer switch of the present invention.

Fig. 7 is a structural block diagram of the input buffer switch of the present invention.

Fig. 8 is a block diagram of a cache module used in an existing switch.

Fig. 9 is a structural block diagram of one of the implementation methods of the intelligent priority cell buffer module of the present invention.

Fig. 10 is a structural block diagram of the second implementation method of the intelligent priority cell buffer module of the present invention.

Fig. 11 shows a structural block diagram of the third implementation method of the intelligent priority cell buffer module of the present invention.

Detailed ways

Embodiments of the present invention are as follows:

In the communication network shown in FIG. 1, two users use user terminals 11 and 15 to conduct two-way communication respectively. The user terminal 11 includes a terminal application 111 , a cell generation and priority setting module 112 , a cell data extraction module 113 , a transmission quality control module 114 and a line driver interface module 115 . The user terminal 15 includes a terminal application 151 , a cell generation and priority setting module 152 , a cell data extraction module 153 , a transmission quality control module 154 and a line driver interface module 155 . The network switching node 13 includes an input and output port module 131, a switching matrix module 132, and an intelligent priority cell buffer module 133. 12 and 14 are network terminals at network entrances. The solid line connecting user terminal 11 and network terminal 12, network terminal 12 and switching node 13, switching node 13 and network terminal 14, network terminal 14 and user terminal 15 in Fig. 1 represents the two-way communication cable connection between each network equipment .

The default signaling transport connection always exists in the system. The default signaling transmission connection can be manually set by the administrator with reference to the ATM network. Before communication, the terminals 11 and 15 use the Q.2931 protocol to establish a communication virtual connection on the default signaling virtual connection, and the network terminal 12, network switching node 13, and network terminal 14 that pass through the communication virtual connection along the way are checked according to the Q.2931 protocol. And reserve network resources, assign virtual connection identification numbers for each link along the way. After the communication virtual connection is successfully established, two-way communication between the user terminals 11 and 15 can be performed.

During communication, the user data generated by the terminal application 111 in the communication terminal 11 is encapsulated in the cell shown in FIG. 2 by the cell generation and priority setting module 112 . The cell includes a connection identification field 21, a payload type field 22, other control fields 23 and valid user data 24. User valid data is encapsulated in the payload part 24 of the cell, and there are special requirements for The cells set a particular cell payload type. The payload type field 22 includes an urgent transmission indication 221 , a delay sensitive indication 222 , an important data indication 223 , a flow violation indication 224 and other flag bits 225 . Delay-sensitive data and special control commands for retransmission can set the urgent transmission indication 221 to be valid; a small number of data cells with relatively high timing requirements can set the delay-sensitive indication 222 to be valid; a small number of cells containing more important encoding parameters can be set to Important data indication 223 is valid. Finally, the communication terminal 11 sets the connection identification field 21 in the letter header with the virtual connection identification number (that is, the combination of VPI and VCI) allocated by the network terminal 12 .

The following example can further illustrate the method for setting the above priority. If the terminal application 111 adopts the adaptive rate coding technology, coded data with different importance and requirements are usually generated. For example, a video signal is a data stream obtained by encoding a series of continuous image frames. The encoded data of these image frames can be divided into image contour signal encoding with lower resolution and image detail encoding with higher resolution. In addition, some image frame data is also inserted with time stamp data to help timing. The image contour signal encoding data volume is small, which is very important for image restoration, so the cell encapsulated with the image contour signal encoding should set the important data indication 223 to be valid; the receiving end needs to receive the time stamp data in time to ensure the smooth playback of the video stream. Therefore, the cell encapsulating the time stamp data should set the delay sensitive indication 222 to be valid. If the receiving end has not received the time stamp data for a long time, the sending end should insert the time stamp data immediately, and set the emergency transmission indication 221 to be valid for the cell encapsulating the time stamp data.

Consider another practical situation. When sending e-mail, the user may accidentally enter the wrong receiving address and press the send button, and the user wants to immediately abort the unfinished e-mail sending. At this time, the user's terminal application 111 can generate a "cancel" control command, and at the same time set the urgent transmission indication 221 to be valid for the cell encapsulating the command.

The encapsulated cells are buffered by the transmission quality control module 114, converted into line transmission signals by the line driver interface module 155, and sent to the network terminal at the network entrance via the communication transmission line.

An internal structure of a network terminal and an external two-way flow relationship are shown in FIG. 3 , which includes a user terminal 11 , a network terminal 12 a and a switching node 13 . The network terminal 12a includes an effective cell arrival rate measurement unit 121 , a cell buffer queue 122 , an intelligent control unit 123 , a database unit 124 , a cell discarding priority change unit 125 and an address filtering and cell distribution unit 126 .

The network terminal may also have other implementation structures, such as shown in FIG. 4 and FIG. 5 . In Fig. 3, the cell data is always output from the cell buffering queue 122 to the cell discarding priority changing part 125, while in Fig. 4's 12b and Fig. 5's 12c A bidirectional data channel is set between them, so that the cell discarding priority changing unit 125 can directly operate the cells in the cell buffer queue 122.

After the network terminal 12 at the network entrance receives the cell sent by the user terminal 11, it performs a contract check on the cell rate of the user's incoming traffic according to the service quality contract reached when the connection is established. The intelligent control unit 123 finds the service quality parameters related to the communication virtual connection in the database unit 124 according to the virtual connection identification number 21 provided by the header, including the reliable cell transmission rate promised by the network to the user. The effective cell arrival rate measurement component 121 monitors and counts the effective cell arrival rate of each communication virtual connection, which may include classified cell arrival rates calculated according to different cell priorities.

According to the monitoring results, the intelligent control unit 123 instructs the cell discarding priority changing unit 125 to set the flow violation indication 224 valid for arriving cells according to a certain priority order when it is determined that the effective cell arrival rate exceeds the service quality agreed value. The general principle is to first set the traffic default indication 224 to be valid for ordinary cells, then set the traffic default indication 224 to be valid for delay-sensitive cells, important data cells, and finally urgent transmission cells. If after ignoring the valid cells of the traffic default indication 224, the traffic of valid cell arrivals no longer exceeds the agreed reliable cell transmission rate, then stop setting the traffic default indication of arriving cells as valid. When the dynamic balance is reached, the ratio of the valid arriving cells with traffic default indication to all valid arriving cells is set to be the same as the ratio of overspeed cells to valid arriving cells. There are many specific implementation methods for this priority setting principle.

The intelligent control unit 123 can calculate the ratio of the effective cells for which the traffic violation indication 224 needs to be set to be valid at each priority level to all valid arrival cells of the priority level according to the measurement result of the effective cell arrival rate measurement unit 121 . In the implementation structure shown in FIG. 3 , the cell discarding priority changing unit 125 sets the flow violation indication 224 for the cells output from the cell buffer queue 122 and arriving from the user terminal according to the ratio calculated by the intelligent control unit 123 It is valid. If the network terminal does not use the cell buffer queue, it is equivalent to the case where the buffer capacity of the cell buffer queue 122 in FIG. 3 is reduced to zero. At this time, the cell discarding priority can still be set for the arriving cell according to the calculated setting ratio for each priority.

For example, it is necessary to set the traffic default indication to be valid for 10% of common cells, then the cell discarding priority changing unit 125 will set the traffic default indication 224 to be valid for one of them every time 10 cells are forwarded. For another example, it is necessary to set the flow default indication for all common cells and 30% delay sensitive cells, then the cell discarding priority change unit 125 is effective for setting the flow default indication 224 for each common cell received, and for the received Each time-delay-sensitive cell of , sets the traffic default indication 224 to be valid with a probability of 30%. There is a lot of literature describing how to achieve a specific operation with a certain probability. The typical approach is to use a random number generator uniformly distributed between 0 and 1. If it is necessary to set the flow default indication of the delay-sensitive cell to be effective with a probability of 30%, the random number generator is triggered once when a new delay-sensitive cell arrives; when the output of the random number generator is less than or equal to 0.3, the time is set The flow violation indication of the delay-sensitive cell is valid, and when it is greater than 0.3, the delay-sensitive cell is allowed to pass directly. There is also a simple way to achieve proportional setting as well, this method uses an accumulating proportional variable K. Assuming that the flow default indication needs to be set for common cells with a ratio of k, the operation of K=K+k is performed every time a new common cell arrives. If the result K is greater than or equal to 1, set the traffic default indication 224 of the ordinary cell to be valid, and subtract 1 from the value of K; otherwise, the traffic default indication flag of the ordinary cell is not set.

In the implementation structure shown in Fig. 5, the cell discarding priority changing part 125 sets the flow default for the cells arriving in the cell buffering queue 122 from the user terminal according to the setting ratio of each priority calculated by the intelligent control part 123 Indication 224 is valid. In the realization structure shown in Fig. 4, both can when cache queue 122 outputs, according to the ratio that intelligent control part 123 calculates as the probability of random setting, by cell discarding priority changing part 125 to output cell with random The method of setting is to set the traffic default indication to be valid; it is also possible to directly set the traffic default indication to be valid for the cells of each priority that arrive at the cell buffer queue 122 according to the setting ratio of each priority calculated by the intelligent control unit 123 .

The network terminal 12 does not discard any user data cells, it then continues to send all received user data cells to the network switching node 13 no matter whether the flow violation indication is set or not.

The network terminal 14 can be implemented with the same method and structure as the network terminal 12 . It also checks the arrival traffic contract of the data cells sent by the user terminal 15 according to the quality of service contract reached when the connection is established, and performs cell discarding priority marking on the super-speed cells according to a certain priority order. , and send them to the network switching node 13 together.

The network function of the intermediate network switching node 13 is completed by a network switch placed at the network switching node 13 . The network switch uses a switch matrix module 132 to switch arriving cells to their respective destination ports for output. It uses the virtual connection identification number 21 carried by the arriving cell to determine the transmission and forwarding address of the cell and the next virtual circuit connection, and forwards the cell from the network terminal 12 to the network terminal 14, and the cell from the network terminal 14 Forward to the network terminal 12, and replace the original virtual connection identification number 21 in the header with the new virtual connection identification number.

In order to prevent cell loss caused by resource competition at the switching node 13 and ensure that the cell loss probability at the switching node 13 meets the requirements of transmission service quality, the switch needs to use cell buffering. There are multiple connection modes such as output buffer, input buffer, central buffer, and distributed buffer between the intelligent priority cell buffer module 133 and the switch matrix module 132 in the switch. Fig. 6 and Fig. 7 illustrate the structural connection relationship between the smart priority cell cache module 133 and the switch matrix module 132 in the present invention by taking the output cache and the input cache as an example. Matrix module 132 and intelligent priority cell buffer module 133, but the present invention includes but not limited to switches using output buffer and input buffer.

A common switch uses a non-intelligent cell buffer module 134 as shown in FIG. 8 instead of the smart priority cell buffer module 133 . This non-intelligent cell buffer queue includes a non-intelligent cell discard control device 1341 and a cell buffer queue 1342 . The cell buffer queue 1342 sets an alarm threshold, such as 60% buffer capacity. When the length of the buffer queue exceeds the alarm threshold, that is, when the space used by the cell buffer queue exceeds 60% of the total buffer capacity, the buffer queue generates an alarm signal and enters an alarm state. The alarm signal is transmitted to the non-intelligent cell discard control device 1341 through the dotted line. When the buffer queue 1342 is in an alarm state, the non-intelligent cell discarding control device 1341 discards all cells marked with traffic violation flags indiscriminately. When the buffer occupancy rate is lower than the alarm threshold, the buffer queue 1342 exits the alarm state, and the cell discarding device 1341 no longer discards cells, and it sends all arriving cells into the buffer queue 1342 for output.

The present invention is characterized by the use of an intelligent priority cell buffer module 133 . FIG. 9 shows an implementation structure 133a of the intelligent priority caching module. It divides the capacity of the cell buffer queue into two parts, the reserved part 1332b and the contention part 1332a. The reserved part 1332b is a resource reserved by the switching node when the connection is established. It is used to cache the contract-keeping cells, and its size is sufficient to ensure that the loss probability of the contract-keeping cells at the switching node is lower than the value agreed in the quality of service parameter. The contention part 1332a is a buffer queue with priority, so it can also be called a priority cell buffer queue, and it is used for buffering default cells. In the present invention, the transmission priority of the obedient cell is higher than that of the default cell, so the default cell buffered in the contention part 1332a is output only after the default cell buffered in the reserved part 1332b is cleared. The division of priorities in the priority cell buffer queue 1332a can refer to the cell payload type, for example, according to the three indicators of urgent transmission indication 221, delay sensitive indication 222 and important data indication 223, each aspect is divided into high and low. levels, and set 8 priority levels in the cache queue. Obviously, the more priorities you set, the more complicated it is to implement. It is also possible to set different priorities for the two operations of cell output and cell discard in the buffer queue.

An optimal method for setting the priority of cell transmission is to set the cell with the effective urgent transmission indication 221 as the highest priority 5, and set the cell with the delay sensitive indication 222 and the important data indication 223 as the priority 4, Set the cell with valid delay sensitive indication 222 but invalid important data indication 223 as priority 3, set the cell with invalid delay sensitive indication 222 but valid important data indication 223 as priority 2, and set transmission priority flag bits as invalid Ordinary cells with the lowest priority 1. The cells with low transmission priority are output from the priority cell buffer queue 1332a after all the cells with high transmission priority have been output.

An optimal cell discarding priority setting method is to set the effective cell of the urgent transmission indication 221 as the lowest priority 1, and set the simultaneously effective cell of the delay sensitive indication 222 and the important data indication 223 as the priority 2, Set the cell whose delay sensitive indication 222 is invalid but the important data indication 223 is valid as priority 3, set the delay sensitive indication 222 valid but the important data indication 223 invalid cell as priority 4, and set the transmission priority flag bit to be invalid The common cells are the highest priority 5. When congestion occurs, the queue length of the priority cell buffer queue 1332a will continue to increase. At this time, the intelligent cell discarding control device 1331 controls to discard some default cells.

One method is to set multiple alarm thresholds for the priority cell buffer queue 1332a, for example, corresponding to the 5 discarding priorities, set 4 alarm thresholds, from m1 to m4, the corresponding queue length and buffer occupancy rate gradually raised. When the queue length of the priority cell buffer queue 1332a exceeds m1, the intelligent cell discarding control device 1331 discards the default cell with the highest cell discarding priority, that is, the priority is 5, so that the cell discarding priority is lower than The default cell of 5 enters the priority cell buffer queue 1332a; when the queue length of the priority cell buffer queue 1332a exceeds m2, the intelligent cell discarding control device 1331 discards the default cell whose discarding priority is higher than or equal to 4 Cells, let the cells discard default cells with a priority lower than 4 and enter the priority cell buffer queue 1332a; and so on. Finally, when the priority cell buffer queue 1332a is full, the intelligent cell discard control device 1331 discards all arriving default cells.

The optimal cell discarding method is to discard default cells when the priority cell buffer queue 1332a overflows. The status of the priority cell buffer queue 1332a is reported to the intelligent cell discard control device 1331 through the control signal channel shown by the dotted line. The intelligent cell discarding control device 1331 first takes out and discards the default cells with high cell discarding priority in the queue, and when there is no default cell with a higher cell discarding priority to be discarded, then discards the cells with a lower cell discarding priority. cell. Specifically, corresponding to the 5-level discarding priority, the cell with the discarding priority of 5 is discarded first. If all cells with a cell discard priority of 5 are discarded, but default cells with a cell discard priority lower than 5 still arrive, the default cells with a cell discard priority of 4 are discarded. Finally, when there is no default cell with a cell discard priority higher than 1 in the queue, the cell discard control device 133 discards all arriving default cells.

The method for further improvement is: set the cell transmission priority of the contract-keeping cell as the highest priority and set it as priority 6, and the cell discarding priority of the contract-keeping cell as the lowest discarding priority and set it as priority 0, And adopt the priority cell cache queue management method similar to the above, so that the buffer queue reserved part 1332b and the contention part 1332a are combined into one again, and used as a larger priority cell buffer queue 1332 , to better play the role of statistical multiplexing of the cache queue in the switch. The structure of the merged intelligent priority cell buffer module is shown in FIG. 10 , which includes an intelligent cell discard control device 1331 and a priority cell buffer queue 1332 .

At this time, the best cell transmission method is still: the cells with low transmission priority are output from the cell priority buffer queue 1332 after all the cells with high priority are output. The method of discarding cells when congestion occurs requires a small modification of the cell discarding method described above. If the method of setting multiple alarm thresholds is adopted, five alarm thresholds should be set accordingly. When the queue length exceeds the first threshold, cells with the highest priority (5 in this example) are discarded, and so on, until Discard all arriving cells when the buffer queue is full at last; If adopt when the priority cell buffer queue overflows, just take out from the buffer queue and discard the method of high cell discarding priority cell, so finally when there is no cell discard in the buffer queue 1332 All arriving cells are discarded only when defaulting cells with a priority higher than 0 are discarded.

The intelligent priority cell cache module can also be realized with the structure shown in FIG. 11 . When this structure is adopted, the optimal transmission method is: the cells with low transmission priority are output from the cell priority buffer queue 1332 after all the cells with high priority are output. The optimal cell discarding method is: when the priority cell buffer queue overflows, take out and discard the cells with high cell discarding priority from the buffer queue, and when there are no cells with higher cell discarding priority to discard, then Discard Cells Discards cells with a lower priority, and discards the last arriving cell when there is no default cell to discard.

The network terminal 12 receives the cell sent by the switching node 13, and the arriving cell filters and distributes the component 126 according to the address according to the virtual connection identification number 21 carried by the cell to judge that the final destination is the user terminal 11, so from the corresponding output port They are sent to the user terminal 11. Similarly, the network terminal 14 also sends the cell sent by the switching node 13 and whose final destination is the user terminal 15 to the user terminal 15 .

After the user terminals 11 and 15 receive the cells sent by the communication counterparts, the line driver interface module 155 restores them into cell data and sends them to the transmission quality control module 114 . The transmission quality control module 114 checks the loss of cells during transmission, and reports to the communication peer through signaling cells. The communication peer can reduce the transmission rate, thereby reducing the cell loss probability and improving the transmission quality. The transmission quality control module 114 sends the received cell to the cell data extraction module 113, and the cell data extraction module 113 takes out valid user data from the cell payload part 24, and submits it to the desired end user, thereby completing Two-way communication process.

The network terminals 12 and 14 can be integrated into the input and output port module 131 of the switch 13, thereby simplifying the installation process of the network. However, before the actual exchange of user traffic, it cannot be defaulted to perform traffic contract inspection and overspeed cell marking operations on the network terminal. It enables the network to distinguish user traffic that violates the rules, so that measures can be selectively taken against a small number of users who maliciously use the network to ensure the stable operation of the entire network. The best place for this kind of traffic contract inspection and overspeed cell marking is at the network entrance, that is, the network device closest to the user. At this time, the network has better scale expansion performance.

Claims (9)

1. explicit priority cell trunking method, it is a kind of quality of service requirement according to communications, method by reallocation priority after the signaling negotiation foundation communication virtual connections, it is characterized in that: the information source transmitting terminal is when producing and send cell, and the specific information content of carrying according to each cell is cell setup different cell transmission priorities; The valid cell arrival rate of the network terminal monitoring communication virtual connections at Web portal place is provided with cell loss priority to arriving cell; Network switching node uses the Internet resources transmission service contract bandwidth of reserving with interior cell, presses cell priority transmission contract bandwidth cell in addition with remaining Internet resources.

2. explicit priority cell trunking method according to claim 1, it is characterized in that: whether immediately the cell transmission priority that described information source is set comprises the index of transmission, transmission delay height and three aspects of the transmission degree of reliability at least, represents with the urgent transmission indication in the cell payload type field, delay sensitive indication and significant data indication; The cell loss priority that the network terminal is set is relevant with the valid cell arrival rate, represents with the promise breaking of the flow in cell payload type field indication.

3. according to claim 1,2 described explicit priority cell trunking methods, it is characterized in that: the valid cell arrival rate of the network terminal monitoring communication virtual connections at described Web portal place, to the service contract bandwidth with the lower cell loss priority of interior cell setting, to exceeding the hypervelocity flow of service contract bandwidth, shunt out according to the order screening from low to high of cell transmission priority and be labeled as higher cell loss priority.

4. explicit priority cell trunking method according to claim 1 is characterized in that: described switching node preferentially abandons the lower cell of transmission priority when network congestion, abandons the higher cell of transmission priority again.

5. explicit priority cell trunking method according to claim 1 is characterized in that: the Internet resources of described reservation include only the minimum value of bandwidth application.

6. explicit priority cell trunking method according to claim 1 is characterized in that: comprise connecting identification field (21), payload type field (22), other control fields (23) and validated user data (24) in described cell; Wherein payload type field (22) comprises urgent transmission indication (221), delay sensitive indication (222), significant data indication (223), flow promise breaking indication (224) and other flag bit (225), communication terminal (11) is arranged on connection identification field (21) in the letter head to the virtual connections identifier that is distributed by the network terminal, and user's valid data are encapsulated in the payload part of cell (24).

7. explicit priority cell the trunking method according to claim 1 and communication that proposes realizes system, it is characterized in that: described system comprises exchange contact (13), the network terminal (12), (14) that link to each other with above-mentioned switching node (13) respectively, and the user terminal that links to each other with the network terminal respectively (11), (15); Wherein user terminal contains and links to each other with the network terminal so that send the line transmissions that is converted to by cell data to the network terminal, and revert to the circuit driving interface (115) that receives cell data at opposite steering handle line transmissions, (155), with circuit driving interface (115), (155) two-way interactive connects to keep the cell-buffering formation that sends and receive and to abandon the transmission quality control module of checking (114) to whether cell having taken place, (154), it is cell setup again to transmission quality control module (114) behind the different transmission priority according to the transmission quality requirements of certain content simultaneously that the communication data that produces is encapsulated into cell, (154) cell that sends generates and priority level initializing module (112), (152), from transmission quality control module (114), take out terminal applies (111) in the cell of the correct reception of (154) sending, (151) the cell data extraction module (113) of desired data, and receive cell data extraction module (113) (153),, (153) data of sending also generate and priority level initializing module (112) to cell, (152) terminal applies (111) of transmission communication data, (151); The network terminal (12) contains the valid cell arrival rate measurement component (121) of monitoring from subscriber side terminal each connection traffic state always, receive and the cell buffer queue (122) of the cell that buffer memory is sent here from the user side direction, measurement result according to arrival rate measurement component (121) judges with the parameter information that is connected in being stored in Database Unit (124) in advance whether the valid cell arrival rate surpasses the Based Intelligent Control parts (123) of contract, storage connects the Database Unit (124) of parameter information, according to the indication of Based Intelligent Control parts (123) to the cell setup cell loss priority of receiving from user side after again the cell of receiving to the cell loss priority change parts (125) that the network switching node (13) that links to each other sends, all link to each other with switching node with user terminal, receive cell that switching node sends here and they are transmitted to the arrival cell of user terminal by address filtering and dispensing member (126); The network terminal (14) has and the identical structure of the network terminal (12); Network switching node (13) contains input and output port module (131), switch fabric module (132) and intelligent priority cell cache module (133).

8. explicit priority cell the trunking method according to claim 7 and communication that proposes realizes it is characterized in that system: in the described network switching node (13) intelligent priority cell cache module (133) contain be serially connected between this network switching node input and the output and each other the intelligent cell of bidirectional interconnect abandon control device (1331) and priority cell buffer queue (1332).

9. explicit priority cell the trunking method according to claim 8 and communication that proposes realizes it is characterized in that system: described priority cell buffer queue (1332) comprises with intelligent cell and abandons the priority cell buffer queue (1332a) of control device (1331) interconnection and abandon the buffer queue reserved part (1332b) that control device (1331) output links to each other with above-mentioned intelligent cell.

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