KR101583091B1 - The method for transmitting the downlink flow control information in the epon system - Google Patents

Abstract

The present invention provides a flow control information delivery method for delivering downstream flow control information of an Ethernet passive fluorescence network, which method comprises detecting whether congestion has occurred in a keasket port of a fiber optic cable termination device, Step S402 of setting authorization, and step S404 of periodically checking the flow control authorization and performing corresponding processing based on the result of the inspection. Thus, according to the present invention, the network element device of the Ethernet passive optical network can support the transmission of the downstream flow control information from the optical line terminal to the optical network unit, enhances the function of the Ethernet passive optical network device, Improves network efficiency and resilience.

Ethernet passive optical network, optical line termination, keiske port, flow control information delivery

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an Ethernet passive optical network,

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a passive optical network (XPON), and more particularly, to a downlink flow control information delivery method for transmitting downstream flow control information of an Ethernet Passive Optical Network (EPON) .

EPON technology is a new broadband passive optical network technology based on Ethernet. Its essence is the extension of Ethernet in the access network. EPON is a point-to-multipoint structure in a physical topology, but is logically a point-to-point structure. The downlink data transmission is a broadcast format in which all optical network units (ONUs) can receive all downlink data frames from a physical PON (passive optical network) port. On the contrary, the uplink is time division multiplex access (TDMA), and each ONU can transmit uplink data only within the uplink grant time slot allocated by the optical line terminal (OLT). In OLT, a functional block that allocates an uplink time slot to an ONU is called a dynamic bandwidth assignment (DBA). The DBA should not only consider the queue status reported by the ONU when allocating the upstream bandwidth to the ONU, but also consider the service level agreement (SLA) parameters installed by the network administrator in the intermediate ONU. The contents of these parameters are different for different DBA algorithms, but they should include at least two parameters, the best effort bandwidth and the assured bandwidth.

Many OLTs are designed to have a congested structure in order to reduce the cost and converge the transmission rate of the connection layer service. That is, the bandwidth of the cascade port of the OLT is smaller than the sum of the upstream bandwidths of all OLT PON ports. This structure inevitably causes congestion when the upstream transmission amount transmitted from all the ONUs exceeds the available bandwidth of the keiske port. However, the current OLT device does not have a function of back pressure of down flow control information to the ONU. After congestion occurs, the OLT simply discards the data frame received from the ONU at a constant rate. Most of the on-line services of the access network are TCP services, which are highly sensitive to network congestion. If the abandoned service is a TCP service, the user terminal must wait for the timer to time out and send it again. Thereby lowering the throughput of the overall network.

1 is a block diagram of a congested OLT structure in the related art. As shown in FIG. 1, a MAC (Media Access Control) chip of two OLTs is connected to a backboard through one switching chip SW. The interface between the OLT MAC chip and the switch chip is called the network side interface (NNI) with the GMII interface. The interface between the switch chip and the backplane is also called the GMII interface, which is called a skate port. If the total amount of data transmission that each OLT MAC sends to the switch chip exceeds 1 Gbps, congestion occurs in the KSK port of SW. If the flow control function of all the chips is enabled, the switch chip generates congestion at the upper exit port to generate a flow control frame and backs it to the OLT MAC. In the related art, the OLT MAC simply abandons a frame exceeding its cache capability without backpressing the flow control information to the ONU.

Therefore, in completing the function of the EPON, how to efficiently transmit the flow control information from the OLT to the ONU has become very important. Currently, only the technology reported is the method of controlling the transmission amount of the Ethernet passive optical network and the device used for the method (patent application no. 200410070719.9) of the Bonghwa Communication Science Co., Ltd. The method employed in that patent pulls Ethernet flow control mechanisms into the OLT MAC. The OLT MAC transmits the extended pause frame to the ONU, thereby transmitting the downlink control information. However, this method can not be used in the EPON OLT MAC chip which is realized only by specified hardware and conforms to the current 802.3ah standard, and since flow control is performed for all ONUs, it is impossible to distinguish ONUs of different priorities, And the activity was limited.

Accordingly, there is a need for a new downlink flow control information delivery method that solves the above problem and conveys the downlink flow control information of the EPON.

In order to solve the above problem, the present invention solves the problem that the downstream flow control information transmitted from the OLT kaskate port can not be transmitted to the ONU in the current EPON system and transmits down flow control information of the Ethernet passive optical network (EPON) And to provide a flow control information delivery method.

According to one aspect of the present invention, there is provided a method of transmitting downstream flow control information of an Ethernet passive optical network, the method comprising: detecting whether congestion has occurred in a keiske port of an optical line termination apparatus; A step S402 of setting flow control identification, and a step S404 of periodically checking the flow control authorization and performing a corresponding process based on the inspection result.

According to the present invention, the step S402 computes the cache queue occupation rate of the port in real time, determines whether the cache queue occupancy rate of the port exceeds a predetermined threshold value, sets the flow control acknowledgment if the determination result is exceeded, May be deleted.

In addition, according to the present invention, in step S402, the flow control frame received at the upstream port or the network interface is periodically checked, and if the flow control frame is increased by comparing with the previous period (the previous one period) And if the flow control frame is not incremented consecutively for a period of the preset amount, the step of deleting the flow control acknowledgment and setting it to zero may be further included.

According to the embodiment of the present invention, the flow control acknowledgment is realized by a 1-bit register, and flow control acknowledgment can be realized by the amount of software change.

In step S404, if the current flow control acknowledgment is 1, the corresponding process is to perform dynamic reduction on the service level protocol parameter.

In step S404, if the check result flow control acknowledgment is 0, the corresponding process reads the flow control acknowledgment previously stored. If the flow control acknowledgment previously stored is 1, dynamic restoration is performed on the service level parameter. Otherwise, And does not perform processing.

According to the present invention, the dynamic reduction includes the following steps: Step A, setting priority on all optical network units associated with the keScale port, and based on this, leave the two teams of high and low priority teams, If the maximum bandwidth sum of the service level protocol of the optical network unit is less than or equal to the available bandwidth of the keScale port, and if the flow control authorization is 1, then the service level protocol parameter of the optical network unit of the low- The maximum bandwidth of the optical network unit of the optical network unit in the high-priority team according to the first predetermined algorithm if the flow control acknowledgment is still 1, Decreasing the bandwidth and extending one cycle, and step D, the flow control acknowledgment is set to zero Performs paper or maximum effective bandwidth is overlapping the steps C to become the same as the guaranteed bandwidth of all the optical network units.

According to the present invention, the first predetermined algorithm is a maximum effect bandwidth = current maximum effect bandwidth - (original maximum effect bandwidth - guaranteed bandwidth) X%, where X is an assignable value.

Also, the dynamic recovery means that when the test result flow control acknowledgment is 0, the maximum effective bandwidth among the service level protocol parameters of the optical network unit of the high-priority team is recovered to the original value before the dynamic adjustment and one cycle is extended, If it is still 0, increases the maximum effective bandwidth among the service level protocol parameters of the optical network units in the low priority team according to the second predetermined algorithm, and extends one period, until the flow control acknowledgment changes to 1, The above step is repeated until the maximum effective bandwidth of the service level protocol parameters of the optical network unit is recovered to the original value before the dynamic adjustment.

According to the present invention, the second predetermined algorithm is a maximum effective bandwidth = current maximum effective bandwidth + (original maximum effective bandwidth - guaranteed bandwidth) X%, wherein X is an assignable value.

Therefore, according to the present invention, the following effects can be obtained.

Enables the EPON network element device to transmit downstream flow control information from the OLT to the ONU, enhances the function of the EPON device, and improves the efficiency and activeness of the EPON network.

Other features and advantages of the invention will be set forth in detail in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended claims.

The drawings described herein are for the purpose of understanding the present invention only and should not be construed as limiting the present invention in order to understand the present invention.

1 is a block diagram showing a congested OLT structure in the related art,

Figure 2 is a topology diagram of an EPON system,

3 is a diagram illustrating delivery of downlink flow control information according to the present invention,

4 is a flowchart of a downlink flow control information delivery method according to the present invention,

FIG. 5 is a flowchart for detecting congestion and setting up flow control authorization through a software scanning method according to an embodiment of the present invention,

6 is a flow chart for reading a flow control authorization according to an embodiment of the present invention and starting response processing,

7 is a flow diagram of dynamic SLA parameter reduction according to an embodiment of the present invention,

FIG. 8 is a flow chart from the detection according to the embodiment of the present invention until the flow control acknowledgment is set to 0 to the SLA parameter recovery.

An optimized embodiment of the present invention will now be described with reference to the figures below. The optimized embodiments described herein are for the purpose of illustrating and interpreting the invention and are not intended to limit the invention.

2 is a topological view of the EPON system. As shown in the figure, a plurality of ONUs 206 are connected to a PON port of one OLT 202 through a spectroscope 204. A downlink data transmission scheme from the OLT 202 to the ONU 206 is a time division multiple access and a physical layer broadcast scheme, that is, each downlink frame is transmitted to a PON port of all the ONUs 206, and an uplink data transmission scheme from the ONU 206 to the OLT 202 is a TDMA scheme.

The basic idea of the present invention will be briefly described with reference to Fig. 3 below. 3 is a diagram illustrating downlink flow control information transfer according to the present invention.

As shown in FIG. 3, after the NNI port of the OLT receives the flow control information, the data transmission to the SW is temporarily stopped for a predetermined time. At this time, since the occupancy rate of the internal cache queue is increased, Respectively. Then, by dynamically reducing the SLA parameters of each ONU, the uplink grant time slots acquired by each ONU are reduced, i.e., the amount of uplink data transmission is reduced. When the amount of transmission from the ONU decreases, the increase in the cache occupancy rate in the ONU is directly affected, and a flow control frame is generated and transmitted from the UNI port. Finally, the transfer of downlink control information from the OLT NNI port to the ONU's UNI port is realized.

Overall, the basic procedure of the present invention is as shown in FIG. To accomplish the object of the present invention, the downstream flow control information transmission method should include the following steps.

In step S402, it is determined whether congestion has occurred in the keisket port of the optical line terminal, and flow control authorization is set based on the result of the detection.

Step S404, the flow control authorization is checked periodically and a corresponding process is performed based on the inspection result.

In step S402, the number of the flow control frames received is calculated, the cache queue occupancy rate of the port is calculated, and it is determined whether the cache queue occupancy rate of the port exceeds a predetermined threshold value. If the cache queue occupancy rate of the port exceeds a predetermined Setting the flow control acknowledgment if the threshold value is exceeded, and deleting the flow control acknowledgment otherwise.

Optionally, step S402 may periodically statistics the flow control frames received from the keScale port or network side interface, set the down flow control acknowledgment to 1 if the flow control frame is incremented by comparison with the previous period, Otherwise, the step of deleting the flow control acknowledgment and setting it to zero may be further included if the flow control frame is not continuously increased for a predetermined period of time.

FIG. 5 is a flow chart for detecting congestion and setting flow control acknowledgments in a software scanning method according to an embodiment of the present invention. As shown in FIG. 5, the basic idea of the process is to check the congestion state of the OLT kasking port by two methods, a hardware trigger method and a software scanning method.

1, About hardware trigger method:

If the hardware receives a flow control frame and the cache queue occupancy of the port exceeds the set threshold of the flow control, then the congestion indication register (ie downflow control acknowledgment) must be set, - no congestion 1 - congestion).

2, About software scanning method:

Downstream control authorization is the amount of software change. In software, a process periodically checks the cache queue occupancy of a keScale port, establishes a downflow control acknowledgment based on it, and if the MAC chip does not support the checking of the cache queue share, It is determined whether congestion has occurred by checking the change status of the flow control frame received through the port (or network side interface).

The basic step is to trigger the periodic scanning of the software beyond the timer, which reads the flow control frame received from the NNI port and increases it by comparing with the previous cycle, recognizing that congestion has occurred and acknowledging flow control Set. If there is no newly increased flow control frame for consecutive N periods (N assignable), the congestion state is considered to be lost and flow control acknowledgment should be removed. The specific steps are as shown in Figure 5:

Step S502, reads the statistics of the received flow control frame,

Step S504: It is determined whether the flow control frame is incremented. If the flow control frame is incremented, step S506 is performed. If not, step S508 is performed.

Step S506, set flow control acknowledgment,

Step S508, adding 1 to the flow control recovery calculator,

Step S510: If it is judged that the count value at this time exceeds " N ", step S512 is performed, otherwise, the process is bound,

Step S512, deletes the flow control acknowledgment.

According to the embodiment of the present invention, the flow control acknowledgment can be realized with a 1-bit register and with a variation amount of the software.

6 is a flow chart for reading the flow control authorization according to an embodiment of the present invention and starting response processing. As shown in FIG. 6, the process periodically checks the flow control acknowledgment and preserves the state value after the previous state transition. If the current flow control acknowledgment is " 1 ", the dynamic reduction process of the SLA parameter is started. Otherwise, it is determined whether or not the stored state value is " 1 ", and if it is " 1 ", the SLA parameter recovery process is started. The specific procedure is as follows:

Step S602, reading the flow control acknowledgment,

Step S604: It is determined whether or not the current flow control authorization is " 1 "; if " 1 ", step S606 is performed;

Step S606, performs dynamic reduction of the SLA,

Step S608, reading the original value of the flow control acknowledgment,

In step S610, it is determined whether the original value is " 1 ". If the value is not " 1 ", the process is bound.

Step S612, performs SLA recovery.

7 is a flowchart of SLA parameter dynamic reduction according to an embodiment of the present invention. The dynamic reduction includes the following steps: Step A, all optical network units associated with the keScale port are prioritized and divided into two teams, the high priority team and the low priority team, and at the same time all optical network units The maximum effective bandwidth of the service level protocol of the keScale port is less than or equal to the available bandwidth of the keSke port. Step B, when the flow control acknowledgment is 1, the maximum effective bandwidth among the service level protocol parameters of the optical network units of the low-priority team is reduced to the guaranteed bandwidth and one period is extended. At step C, if the flow control acknowledgment is still 1, the maximum effective bandwidth among the service level protocol parameters of the optical network units of the high-priority team is reduced according to the first predetermined algorithm and the one-period is extended. Step D is repeatedly performed until the flow control acknowledgment is set to 0, or until the maximum effective bandwidth of all the optical network units becomes equal to the guaranteed bandwidth.

An example of dynamic reduction is shown in Fig. One of the ONUs involved in the congestion message should have different priorities and be divided into two teams according to their priority, and the other is that the sum of the SLA maximum effective bandwidths of all ONUs is used by the SW keSke port Two prerequisites are needed, which must be less than or equal to the available bandwidth.

The basic process of dynamic reduction is as follows:

Step S702, the recognition of the work step is read,

In step S704, it is determined which stage of the current adjustment process, in which stage 1 is the stage of the adjustment standby low-priority ONU team SLA and stage 2 is the stage of the adjustment standby high-priority ONU team SLA, S706 is performed,

Step S706, the maximum effective bandwidth among the SLA parameters of the ONUs in the low-priority team is reduced to the guaranteed bandwidth and one period is extended. If step 2, step S708 is performed.

Step S708 reads the SLA maximum effective bandwidth of the ONU among all the high-priority teams,

In step S710, if the maximum effective bandwidth is the same as the guaranteed bandwidth, the process determines whether the maximum bandwidth is equal to the guaranteed bandwidth, and if not, the process proceeds to step S712.

In step S712, the maximum effective bandwidth among the SLA parameters of the ONUs in the high-priority team is reduced to the current maximum bandwidth - (original maximum bandwidth-guaranteed bandwidth) X% and the one bandwidth is extended by the same ratio. Among them, X is an assignable value. The flow control acknowledgment changes to " 0 " or the maximum effective bandwidth of all ONUs becomes equal to the guaranteed bandwidth.

8 is a flow chart from the flow control authorization detection to the SLA parameter recovery according to the embodiment of the present invention. As shown in FIG. 8, the process includes the following steps:

Step S802, the recognition of the work step is read.

Step S804, to determine which stage of recovery is currently in progress. Step 1 is the recovery standby high priority ONU team SLA stage and step 2 is the recovery standby low priority ONU team SLA stage. If the current step is the first step, step S806 is performed, and if it is the first step, step S808 is performed.

In step S806, the maximum effect bandwidth among the SLA parameters of the ONUs in the high-priority team is recovered to the initial value before the parameter dynamic reduction operation, and one cycle is extended.

In step S808, the SLA maximum effective bandwidth of the ONU among all the high-priority teams is read.

In step S810, it is determined whether the maximum effective bandwidth is smaller than the initial value. If the maximum effective bandwidth is still smaller than the initial value, step S812 is performed.

If the flow control acknowledgment is still " 0 " (that is, if it is smaller than the initial value), the maximum effective bandwidth among the SLA parameters of the ONUs of the low-priority team is set to the guaranteed bandwidth + (original maximum bandwidth- Guaranteed bandwidth) x X% and extend one cycle. Among them, X is an assignable value. The flow control authorization is changed to " 1 " or the maximum effect bandwidth among the SLA parameters of all the low priority ONUs reaches the initial value before the SLA parameter dynamic reduction operation.

Since the downlink flow control information transmission method as described above is used, the EPON network element device can transmit downstream flow control information from the OLT to the ONU. In addition, the method of the present invention is simple to implement and simple to control, enhancing the functionality of EPON devices and improving the efficiency and versatility of the EPON network.

The foregoing is not intended to limit the present invention to the optimized embodiments of the present invention. Those skilled in the art can make various changes and changes in the present invention. All such equivalents, equivalents, modifications and the like which are within the scope of the present invention are within the scope of the present invention.

Claims (11)

A method for transmitting downstream flow control information of an Ethernet passive optical network, It is determined whether or not congestion has occurred in the keasket port of the optical line terminating device, the flow control authorization is set based on the result of the detection, A flow control frame received at the keScale port or the network side interface is periodically measured, The flow control acknowledgment is set to 1 if the flow control frame is increased as compared to the previous period and the flow control acknowledgment is deleted if the flow control frame is not incremented consecutively for a preset positive period, Step S402 of setting, And a step (S404) of periodically checking the flow control authorization and performing a corresponding process based on the inspection result. The method according to claim 1, In step S402, Calculates the cache queue occupancy of the port in real time, Determining whether the cache queue occupancy of the port exceeds a predetermined threshold, And setting the flow control acknowledgment if the occupancy rate exceeds a predetermined threshold and otherwise deleting the flow control acknowledgment. 3. The method of claim 2, Wherein the flow control acknowledgment is realized by a 1-bit register. 3. The method of claim 2, Wherein the flow control acknowledgment is realized by a software change amount. The method according to claim 1, Wherein in step S404, if the current flow control acknowledgment is 1, the corresponding process performs a dynamic reduction on a service level protocol parameter. 6. The method of claim 5, In step S404, if the examined flow control acknowledgment is 0, the corresponding process is The stored flow control authorization is read, Wherein if the flow control acknowledgment is 1, then dynamic recovery is performed on the service level protocol parameter, otherwise no processing is performed. The method according to claim 6, The dynamic reduction Setting priority for all optical network units associated with the keeze port and dividing the optical network unit into two teams, a high-priority team and a low-priority team based on the priority, A step A of ensuring that the sum is less than or equal to the available bandwidth of the keiska port, and if the flow control acknowledgment is equal to 1, the maximum effective bandwidth of the service level protocol parameters of the optical network unit of the low- Step B, which reduces bandwidth and extends one period, (C) decreasing a maximum effective bandwidth among the service level protocol parameters of the optical network units of the high-priority team according to a first scheduled algorithm and extending one period according to a first scheduled algorithm, Step D of repeating Step C until the flow control acknowledgment is set to 0 or until the maximum effective bandwidth of all optical network units becomes equal to the guaranteed bandwidth To the flow control information. 8. The method of claim 7, The first scheduling algorithm Maximum effective bandwidth = current maximum effect bandwidth - (original maximum effective bandwidth - guaranteed bandwidth) x X%, where X is an assignable value. 8. The method of claim 7, The dynamic recovery If the checked flow control authorization is 0, restores the maximum effective bandwidth of the service level protocol parameters of the optical network unit of the high-priority team to the original value before dynamic reduction and extends one period, If the flow control acknowledgment is still 0, the maximum effective bandwidth of the service level protocol parameters of the optical network units of the low priority team is increased and one cycle is extended according to the second predetermined algorithm, And repeating the above steps until the maximum effective bandwidth of the service level protocol parameters of the optical network units in the low-priority team is restored to the initial value before the dynamic reduction, until the flow control acknowledgment is changed to 1 Control information delivery method. 10. The method of claim 9, The second scheduling algorithm Maximum effective bandwidth = current maximum effective bandwidth + (original maximum effective bandwidth - guaranteed bandwidth) x X%, where X is an assignable value. delete

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