KR20040026342A - Media access control scheduling method and EPON system using the method - Google Patents

Abstract

PURPOSE: A media access control protocol operating method and an Ethernet optical network system using the same are provided to enhancing an optical media access function of an optical subscriber line section and transmission delay time by providing an optimum band width by using both a dedicated band width and a dynamically variable band width service. CONSTITUTION: An OLT(Optical Line Terminal)(11) has a transmission and reception function of terminating one end of a line, fixedly allocates a dedicated band width, a variable band width and a certain band width according to a band width service form that ONUs(Optical Network Unit)(12-14) request respectively, and provides an optimum band width to respective ONUs(12-14) by using a mixed(dedicated+variable) band width service variably supporting an extra band width in a frame. The ONUs(12-14) has a transmission and reception function of terminating one end of the line at the side of an optical subscriber and also has a function of requesting a required band width from the OLT(11). A passive optical distributor(15) distributes a signal from the OLT(11) to the ONUs(12-14) or combines signals received from the ONUs(12-14) to one signal and transmits it to the OLT(11) according to a transfer direction of an optical signal.

Description

Media access control scheduling method and Ethernet optical network system using the same

The present invention relates to a media access control (MAC) between an optical line terminal (OLT) and an optical network unit (ONU) in an Ethernet passive optical network (EPON). In more detail, the media access control protocol processing between the optical fiber terminator and the optical fiber terminator is implemented to provide an optimal bandwidth by simultaneously using a fixed bandwidth service and a dynamic variable bandwidth service according to the bandwidth service type of the optical fiber terminator. The present invention relates to a method for operating an Ethernet passive optical media access control protocol.

The Ethernet passive fiber is based on fiber at 1 Gbps data rate and is transmitted using Ethernet frames at Layer 2. In this Ethernet passive optical network, one optical fiber terminator and several optical fiber terminators are located at both ends of a passive optical splitter (POS) and each is connected by an optical fiber.

In general, the Ethernet passive optical network is used for data transmission, and the downstream stream from the optical fiber terminator to the optical fiber terminator is broadcast to point-to-multipoint without control of media access, and the optical fiber terminator to the optical fiber terminator. Since upstream accesses media on a multipoint basis, a protocol for media access is required.

The optical media access control protocol of the Ethernet passive optical network has a fixed bandwidth allocation method suitable for quality of service (QoS) services, such as a leased line, and a local area network (LAN / MAN). It is classified into a suitable dynamic variable bandwidth allocation scheme.

The fixed bandwidth allocation scheme for a dedicated line subscriber has a problem in that it does not utilize the allocated bandwidth sufficiently efficiently because it must allocate a time slot corresponding to the contracted bandwidth regardless of whether the allocated bandwidth is used by provisioning.

Dynamic variable bandwidth allocation, which is suitable for best-in-class services such as LAN / MAN, requires the corresponding bandwidth to the fiber terminator to transmit the frames that arrive at the buffer, and the fiber terminator is required by the fiber terminator. Bandwidth is allowed through scheduling.

As the subscriber network structure evolves in various ways and the communication market environment is spreading into the market, one optical fiber terminator provides two services individually or simultaneously to ensure optimal bandwidth allocation according to the service type of optical terminators. There is a need to do it.

However, research on Ethernet passive optical networks continues, but there is no efficient method for dynamically responding to the service type of the optical termination device and guaranteeing optimal bandwidth allocation.

Accordingly, an object of the present invention is a time division multiple access (TDMA) fixed bandwidth allocation scheme suitable for quality of service (QoS) services that require guaranteed bandwidth, such as a leased line, and a time division multiple access suitable for LAN / MAN. By simultaneously implementing the access dynamic variable bandwidth allocation method in one optical fiber terminator, the optical media access function and transmission delay time of optical subscriber line section can be improved.

1 is a block diagram showing the overall configuration of the optical fiber termination device and optical fiber termination device in the Ethernet passive optical network according to the present invention.

2 is a flow chart illustrating an information table recording process according to the present invention.

Figure 3a is a view showing the form of the queue table according to the present invention.

3b illustrates the form of an information table according to the invention;

4 is a flowchart illustrating a process of allocating a variable bandwidth to each optical termination device by using the information table of FIG. 3B.

5 is a flowchart illustrating a message transmission / reception procedure between an optical fiber terminator and an optical fiber terminator when the optical fiber terminator supports only fixed bandwidth.

6 is a flowchart illustrating a message transmission / reception procedure between an optical fiber terminator and an optical fiber terminator when the optical fiber terminator supports only variable bandwidth.

7 is a flowchart illustrating a message transmission / reception procedure between an optical fiber terminator and an optical fiber terminator when the optical fiber terminator supports mixed bandwidths.

The media access control protocol operating method of the present invention for achieving the above object is the first step, the bandwidth information of the requested bandwidth information and the bandwidth information from the optical network termination devices supporting the variable bandwidth required for uplink traffic The second step of calculating the maximum variable bandwidth that can be allocated to the optical fiber termination devices supporting the variable bandwidth according to the service type, and the upstream of the bandwidth service type of the optical fiber termination devices and the total maximum variable bandwidth calculated in the second step. And a third step of transmitting a transmission permission frame to each optical termination device according to the ratio of the available variable bandwidth to the fixed bandwidth except for the fixed bandwidth already allocated for the traffic.

The Ethernet passive optical network system using the above-described method of operating the media access control protocol performs transmission and reception functions for terminating one end of the line at the optical subscriber side and performs the uplink traffic by allocating bandwidth from the optical fiber terminator. For example, a bandwidth allocation is requested from optical fiber termination devices that support a variable bandwidth among optical fiber termination devices to calculate the maximum variable bandwidth that can be allocated to the optical fiber termination devices, and the fixed bandwidth and the variable bandwidth according to the bandwidth service type of the optical fiber termination devices. An optical fiber terminator for allocating at least one of the optical fiber terminators and a signal from the optical fiber terminators according to the transmission direction of the optical signal to the optical fiber terminators, and combining the signals from the optical fiber terminators Passive optical splitter to transmit to.

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

1 is a block diagram showing the overall configuration of the optical fiber termination device and optical fiber termination device in the Ethernet passive optical network according to the present invention.

The optical fiber terminator 11 has a transmission and reception function for terminating one end of a line as an exchange facility and fixed fixed bandwidth, variable bandwidth and constant bandwidth according to the type of bandwidth service required by each optical terminator for uplink traffic. By using a mixed (fixed + variable) bandwidth service, which is allocated at the same time and variably supports the spare bandwidth in the frame, it provides the optimal bandwidth to each fiber termination device.

That is, one optical fiber terminal device 11 provides both a fixed bandwidth service, a variable bandwidth service and a mixed bandwidth service according to the bandwidth service type of the optical fiber termination device.

For this purpose, when the optical fiber terminators transmit their own bandwidth information, the optical fiber terminator 11 allocates the optical fiber terminators to the optical fiber terminators using the bandwidth service type of each optical fiber terminator and the bandwidth information required by the optical fiber terminators. The maximum bandwidth that can be calculated is calculated and recorded in the information table, and then the appropriate bandwidth is dynamically allocated to each fiber termination device according to the ratio of the available bandwidth to the allocated bandwidth.

The optical network termination devices 12 to 14 include a transmission and reception function for terminating one end of the line at the optical subscriber side and have a function of requesting the bandwidth required by the optical ray termination device 11.

In the present embodiment, the optical termination device 12 represents optical termination devices that support only variable bandwidth, and the optical termination device 13 represents optical termination devices supporting both fixed bandwidth and variable bandwidth. 14) represents fiber termination devices supporting only fixed bandwidth.

The passive optical splitter 15 distributes the signal from the optical fiber terminator 11 to each of the optical fiber terminators 12 to 14 or receives the signal from each optical fiber terminator 12 to 14 according to the transmission direction of the optical signal. The signal is transmitted to the optical ray terminating device 11 in combination.

FIG. 2 shows that the optical fiber terminators 11 to 14 each of the optical fiber terminators 12 to 14 when the optical fiber terminators 12 to 14 require a variable bandwidth to the optical fiber terminator 11 according to the present invention. FIG. 3A is a flowchart illustrating a process of recording an information table for a bandwidth request of FIG. 3A, and FIG. 3A illustrates a queue table in which bandwidth information required by each optical termination device is recorded for creating the above-described information table. FIG. It shows form.

Referring to each field of the information table of FIG. 3b, the fixed bandwidth allocated to the optical termination device is recorded in the 'FT', and the variable bandwidth allocated to the optical termination device is recorded in the 'VT'. 'Is recorded whether the fiber termination device supports a fixed bandwidth, and' VF 'is recorded whether the fiber termination device supports a variable bandwidth.

When the optical fiber terminators 12 to 14 require the bandwidth of the optical fiber terminator 11 to transmit data stored in the buffer to the optical fiber terminator 11, the optical fiber terminator 11 is connected to the optical fiber terminators. The bandwidth requested from (12-14) is recorded in the queue information table as shown in Fig. 3A (step 201).

At this time, in the case of the optical network termination device 12 that is assigned only a fixed bandwidth, the optical fiber termination device 11 does not require a bandwidth.

The optical fiber terminating device 11 requests the bandwidth of the optical fiber terminating devices 12 to 14 recorded in the queue information table and the service type of the optical fiber terminating devices 12 to 14 previously registered in the information table as shown in FIG. 3B. Using the information, the maximum variable bandwidth that can be allocated to each of the optical fiber termination devices 12 to 14 is recorded in the information table.

To this end, the optical fiber terminal device 11 determines the service type of each optical fiber terminal device 12 to 14 using the information recorded in the information table, and then the variable bandwidth 'VT [i], i = 0 corresponding to the service type. N 'is calculated.

For this purpose, the optical fiber terminator 11 first searches the 'FF' field value of the information table for each optical terminator 12 to 14 so that each optical terminator 12 to 14 supports a fixed bandwidth. (Step 202).

As a result, since the optical termination device 12 that does not support the fixed bandwidth, that is, FF [1] = 0 supports only the variable bandwidth, the optical termination device (VT [1]) of the optical termination device 12 has an optical termination device ( The bandwidth value 'REQ [1]' requested by 12) and recorded in the queue table is recorded (step 203).

Next, it is checked whether the optical network termination apparatus 13 also supports fixed bandwidth. Since the fiber termination device 13 supports fixed bandwidth, that is, FF [2] = 1, it is then checked whether the fiber termination device 13 supports variable bandwidth by searching the 'VF' field of the information table (step 204).

Since the optical termination device 13 also supports variable bandwidth, that is, the optical termination device 13 supports both fixed bandwidth and variable bandwidth service types (FF [2] = 1, VF [2] = 1). Subtracting the fixed bandwidth value FT [2] assigned to the optical termination device 13 from the bandwidth value REQ [2] required by (13), the remainder is added to the variable bandwidth field 'VT [2]' of the optical termination device 13; Record (step 205). That is, VT [2] = REQ [2]-FT [2].

In this case, the fixed bandwidth FT [2] may be larger than the bandwidth REQ [2] required by the optical termination device 13, in which case, when VT [2] is less than zero, the value is set to '0'. (Step 206).

Since the optical termination device 14 supports only fixed bandwidth (FF [3] = 1, VF [3] = 0), '0' is recorded in the variable bandwidth field 'VT [3]' of the optical termination device 14. (Step 207).

This process is performed for all fiber termination devices (step 208).

When the information table for all optical fiber terminators 12 to 14 is completed through the above-described process, the optical fiber terminator 11 is adapted to the service type to each optical fiber terminator 12 to 14 by using the information table. The variable bandwidth is allocated and the information table is modified when the bandwidth allocation is requested again from the fiber termination devices 12-14.

4 is a flowchart illustrating a process in which the optical fiber terminator 11 allocates a variable bandwidth to each optical network terminator 12 to 14 using the completed information table.

First, the optical fiber terminator 11 obtains the ratio of available space (AT) from the available bandwidth for uplink traffic to the total variable bandwidth request (sum of the 'VT' field in the information table) (excluding the fixed bandwidth) (step 401). That is, AT = (TL-FL) / (sum of VT), where TL represents the size of the frame sent from the optical termination devices 12-14 to the optical fiber termination device 11, and FL is the TL. It represents the sum of the fixed bandwidths already allocated.

When the AT is obtained, the optical fiber terminator 11 allocates an appropriate bandwidth to the optical fiber terminators 12 to 14 based on the size of the AT and the service type of the optical fiber terminators 12 to 14.

That is, each optical fiber terminator 11 first searches the 'FF' field value of the information table for the optical fiber terminators 12 to 14 to determine whether the optical fiber terminators 12 to 14 support a fixed bandwidth. Confirm (step 402).

As a result of the check, it is checked whether the AT is greater than or less than 1 when the fixed network does not support the fixed bandwidth, such as the optical termination device 12 (step 403).

If AT is greater than or equal to 1, it means that the capacity is larger than the required amount. Therefore, the variable bandwidth 'VT [1]' recorded in the information table is converged by converging all the variable bandwidths required by the corresponding fiber termination device 12. (12) (step 404).

If the AT is smaller than 1, the available capacity is smaller than the required amount, and thus the optical termination device 12 allocates a variable bandwidth proportional to the required amount without allocating the required bandwidth (step 405). That is, the bandwidth of VT [1] × AT is allocated to the optical termination device 12.

Next, it is checked whether the optical network termination apparatus 13 also supports fixed bandwidth. Since the fiber termination device 13 supports fixed bandwidth, that is, FF [2] = 1, it is then checked whether the fiber termination device 13 supports variable bandwidth by searching the 'VF' field of the information table (step 406).

In case of supporting the variable bandwidth like the optical termination device 13, that is, supporting both the fixed bandwidth and the variable bandwidth service type (FF [2] = 1, VF [2] = 1), the AT is also higher than 1 It is checked whether it is large or small (step 407).

If AT is greater than or equal to 1, it means that the capacity is larger than the required amount. Therefore, the bandwidth required by the optical fiber terminator 12, i.e., the fixed bandwidth FT [2] recorded in the information table and the method described above are calculated. All of the variable bandwidth VT [2] is converged and allocated to the optical termination device 13 (step 408).

If the AT is less than 1, the available capacity is smaller than the required amount. Therefore, the AT does not allocate all the bandwidth required by the optical termination device 12, and the fixed bandwidth FT [2] is allocated as much as the previously allocated fixed bandwidth. The convergence is allocated as it is, and the variable bandwidth VT [2] is allocated a variable bandwidth proportional to the required amount (step 409). That is, the bandwidth of FT [2] + VT [2] x AT is allocated to the optical termination device 13.

When only the fixed bandwidth is supported like the optical termination device 14, the bandwidth allocated to the fixed bandwidth field 'FT [3]' of the information table is allocated to the corresponding optical termination device 14 (step 410).

This process is performed until the bandwidth allocation is completed for all the fiber termination devices 12-14 that have requested the bandwidth (step 411).

The main point of the present invention described above is to unconditionally allocate the fixed bandwidth as previously allocated fixed bandwidth to the pre-allocated fixed bandwidth, and for each of the remaining bandwidths after subtracting the fixed bandwidth, the optical network termination apparatuses 12 to 14 require. The bandwidth is allocated to the fiber termination devices 12 to 14 in proportion to the degree of bandwidth.

5 to 7 illustrate a message transmission / reception procedure between the optical fiber terminator 11 and the optical fiber terminators 12 to 14 according to the bandwidth service type of the optical fiber terminators 12 to 14.

FIG. 5 illustrates a case in which the optical fiber termination device supports only fixed bandwidth. First, a grant frame including temporal synchronization information and address information for uplink traffic is moved from the optical fiber termination device 11 to the optical network termination device 14. Is sent.

Upon receiving this permission frame, the optical fiber terminator 14 transmits the IEEE 802.3 frames to the optical fiber terminator 11 using a fixed length of time slot allocated to the bandwidth allocated thereto.

FIG. 6 illustrates a case in which an optical fiber terminator supports only variable bandwidth. First, a grant frame including bandwidth information, temporal synchronization information, and address information allocated by the above-described method for upstream traffic is selected from the optical fiber terminator. 11) to the optical fiber terminator 12.

The optical network terminating device 12 receiving this transmits IEEE 802.3 frames to the optical fiber terminating device 11 using the bandwidth allocated from the optical fiber terminating device 11.

When the transmission of the optical fiber terminator 12 is completed, the optical fiber terminator 12 sends a request message to the optical fiber terminator 11 to receive the required bandwidth in order to transmit data in the next frame.

That is, in this method, the maximum length of the bandwidth allocated to each optical termination device 12 is equal to the length of the fixed bandwidth allocation method. Therefore, it is the same as the fixed bandwidth allocation method when the overall frame length is maximum, but it is more efficient since some optical termination devices 12 do not allocate the bandwidth as much as they do not transmit data.

FIG. 7 illustrates a mixed bandwidth scheme in which the optical termination device supports both fixed bandwidth and variable bandwidth. First, fixed bandwidth previously allocated for uplink traffic and variable bandwidth information, temporal synchronization information, and address allocated by the above-described method. A GRANT frame including information is transmitted from the optical fiber terminating device 11 to the optical fiber terminating device 13.

Receiving this, the optical termination device 13 first transmits (QoS) IEEE 802.3 frames of guaranteed transmission quality (QoS) to the optical fiber termination device 11 using a fixed bandwidth allocated, and transmits a variable bandwidth for the remaining spare slots. Transmits the IEEE 802.3 frame to the optical fiber terminating device (11).

When the transmission of the optical termination device 13 is completed, in order to transmit data in the next frame, the optical termination device 13 sends a request message to the optical fiber termination device 11 to be allocated the necessary bandwidth.

As described above, the optical media access function and transmission delay time of the optical subscriber line section are improved by providing the optimal bandwidth by simultaneously using the fixed bandwidth service and the dynamic variable bandwidth service according to the bandwidth service type required by the optical fiber termination device. Efficiently provide services and manage operations.

Claims (12)

A first step of receiving a bandwidth required for uplink traffic from optical fiber termination devices supporting a variable bandwidth; Calculating a maximum variable bandwidth that can be allocated to each optical termination device supporting the variable bandwidth according to the requested bandwidth information and the bandwidth service type required by the optical termination device; And The transmission permission frame is transmitted according to a bandwidth service type required by the optical termination devices and a ratio of available variable bandwidths except for fixed bandwidths allocated for uplink traffic to the total maximum variable bandwidth calculated in the second step. And a third step of transmitting to the end devices. The method of claim 1, wherein the second step When the bandwidth service type of the optical fiber termination apparatus supports only fixed bandwidth, the maximum variable bandwidth is set to O. When the bandwidth service type supports only the variable bandwidth, the bandwidth requested in the first step is converted into the maximum variable bandwidth. In the case of supporting both the fixed bandwidth and the variable bandwidth, the method of operating the media access control protocol according to claim 1, wherein the maximum variable bandwidth is obtained by subtracting the fixed bandwidth allocated from the bandwidth required in the first step. . The method of claim 1, wherein the third step And transmitting the transmission permission frame having temporal synchronization information and address information for uplink traffic to the corresponding optical termination device when the optical termination device supports only fixed bandwidth. The method of claim 1, wherein the third step When the optical fiber termination device supports only the variable bandwidth, transmitting the transmission permission frame including the maximum variable bandwidth information, the temporal synchronization information for uplink traffic and the address information to the corresponding optical network termination device Media access control protocol operation method. The method of claim 4, wherein When the ratio is greater than or equal to 1, the maximum variable bandwidth is allocated to the optical termination devices, and when the ratio is less than 1, the media access is allocated to the optical termination devices in proportion to the ratio. How to operate control protocol. The method of claim 5, wherein The bandwidth proportional to the ratio is a bandwidth as multiplied by the ratio multiplied by the maximum variable bandwidth. The method of claim 1, wherein the third step When the optical fiber terminator supports fixed bandwidth and variable bandwidth, a transmission permission frame including a bandwidth obtained by adding the fixed bandwidth already allocated and the maximum variable bandwidth calculated in the second step, temporal synchronization information, and address information for uplink traffic is generated. Method for operating a media access control protocol, characterized in that the transmission to the optical network termination device. The method of claim 7, wherein If the ratio is greater than or equal to 1, the bandwidth is allocated to the optical termination devices by adding the fixed bandwidth previously allocated to the maximum variable bandwidth calculated in the second step. When the ratio is less than 1, the bandwidth is proportional to the ratio. And a bandwidth is allocated to the optical fiber termination devices. The method of claim 8, And a bandwidth proportional to the ratio is a predetermined bandwidth allocated to the maximum variable bandwidth multiplied by the ratio. Optical network termination devices performing transmission and reception functions for terminating one end of the line at the optical subscriber side and performing uplink traffic by allocating a bandwidth from the optical fiber termination device; A bandwidth allocation is requested from the optical fiber termination devices supporting the variable bandwidth among the optical fiber termination devices to calculate the maximum variable bandwidth that can be allocated to the optical fiber termination devices, and the fixed bandwidth and the bandwidth service type according to the type of bandwidth service required by the optical fiber termination devices. An optical fiber termination device for allocating at least one of a variable bandwidth to the optical network termination devices; And Ethernet passive optical network system having a passive optical splitter for distributing the signal from the optical fiber terminator to the optical fiber terminators according to the transmission direction of the optical signal and combining the signals from the optical fiber terminators to transmit the optical signal to the optical fiber terminator. . The method of claim 10, The optical termination device is an Ethernet passive optical network system, characterized in that any one of a form that supports only fixed bandwidth, a form that supports only variable bandwidth and a form that supports both fixed and variable bandwidth. The method of claim 11, The optical fiber terminator first allocates a fixed bandwidth and supports a variable bandwidth in proportion to the ratio of the available bandwidth excluding the fixed bandwidth and the maximum variable bandwidth that can be allocated to the optical termination devices. Ethernet passive optical network system characterized in that it supports.