WO2008055438A1

WO2008055438A1 - A bandwidth allocation method and device for the pon in which the different transmission rates coexist

Info

Publication number: WO2008055438A1
Application number: PCT/CN2007/070992
Authority: WO
Inventors: Yuntao Wang; Wei Huang; Peng Ou
Original assignee: Huawei Technologies Co., Ltd.
Priority date: 2006-11-09
Filing date: 2007-10-30
Publication date: 2008-05-15
Also published as: JP2010509812A; CN102325083B; JP4891410B2; CN102325083A

Abstract

A bandwidth allocation method for the PON in which the different transmission rates coexist is provided. The category table items are set in the OLT to record the category of ONUs with different transmission rates; the OLT uniformly allocates the time slots for the ONUs with different transmission rates on the basis of the said table items to generate the allocation table items of upstream bandwidth; and according to the allocation table items of upstream bandwidth, the bandwidth allocation instructions of the ONUs with different transmission rates are carried by the downstream optical channel with the corresponding different wavelengths. A bandwidth allocation device for the PON in which the different transmission rates coexist, a method and device for determining the downstream rates of ONUs and a method and device for determining the finding windows to which the ONUs with different rates belong to are also provided.

Description

Method and device for bandwidth allocation for different transmission rates PON coexistence

[1] Technical field

[2] The present invention relates to the field of communications, and more particularly to a bandwidth allocation method and apparatus for coexistence of PONs of different transmission rates.

[3] Background of the invention

[4] At present, many Internet services are accessed through dial-up modems with a transmission rate ranging from 56K to several megabytes, ADSL, cable modem (CM), and VDSL. However, in order to provide various services, such as high-quality video information services, VoD (Video on

Demand), data transmission requires about 100M of bandwidth, and the above several access methods cannot meet the requirements. Therefore, the demand for laying the access network with fiber is rapidly increasing, and the passive optical network (PO N) is positive. It is a user access network that can meet the requirements of these new services and is economical and convenient to operate and maintain. As shown in Figure 1, the structure of the PON multicast network is shown. The passive optical network accesses signals from the optical network line terminal (OLT). Assigned to each client through the Optical Distribution Network (ODN) (ONU/

ONT, ONT is the optical network user terminal, directly located at the user end; and the ONU is the optical network subscriber unit, and other networks such as Ethernet between the users, and the multimedia signal can be viewed at the user end. The OLT is located at the central office, the ONU/ONT is located at the user end, and the direction of the OLT to the ONU/ONT is the downlink direction, and vice versa. Bian downstream direction 1 min _16, 1 min ₃₂ min ₁ ₆₄ or the like based on a multicast distribution scheme inches division multiplexed optical signal input from the ODN will be assigned by the OLT average output power to a number of clients, generally

[5] Current commercial PON systems operate at up to 1 Gbps transmission rate. When the 1:32 branch is compared, each user can divide the bandwidth to about 30M. Due to the rise of network services such as Internet TV (IPTV) and video telephony, 30 M bandwidth cannot meet the needs of users.

[6] Therefore, the major international standards organizations, IEEE and ITUT, are working on the development of lOGbps.

EPON and high transmission rate industry standard for TDMA-PON. lOGbps

The transmission rate of PON will reach 10OGbps, so the bandwidth of each user will increase by 10 times to 300Mbps.

[7] However, in the case of a large number of lGbps PON users, lOGbps PON must be able to communicate with lGbps. PON systems coexist.

[8] Figure 2 is the optimal coexistence scheme obtained by combining various factors. Downstream lOGbps

The ONU uses 1550 wavelengths, and the lGbps ONU still uses 1490 wavelengths, and the uplink shares a 1310 wavelength.

[9] In the current PON, bandwidth allocation is performed on ONUs of the same transmission rate. However when one

PONs have different transmission rates. ONU吋, for example, lOGbps and lGbps ONU, share an upstream wavelength according to the related technical solutions. Therefore, the OLT needs to perform unified scheduling on the daytime, and needs to find a most efficient bandwidth allocation method.

[10] Therefore, there is a need for a solution for different transmission rate PON coexistence/bandwidth allocation, which can solve the problems in the related art described above.

[11] Summary of the invention

[12] The embodiments of the present invention are directed to a bandwidth allocation method and apparatus for coexistence of different transmission rate PONs, so as to solve the problem that the related technologies have different transmission rates, PON coexistence, and the OLT needs to perform unified scheduling on the inter-time.

[13] The embodiment of the present invention is implemented by the following technical solutions:

[14] An embodiment of the present invention provides a bandwidth allocation method for coexistence of PONs with different transmission rates, including:

[15] Set the category entry in the OLT to record the types of ONUs with different transmission rates;

[16] The OLT performs unified gap allocation on different transmission rate ONUs according to the foregoing entries to form an uplink bandwidth allocation entry;

[17] According to the uplink bandwidth allocation entry, bandwidth allocation commands of different transmission rate ONUs are respectively carried on corresponding downlink optical channels of different wavelengths.

[18] An embodiment of the present invention provides a bandwidth allocation apparatus for coexistence of PONs with different transmission rates, including: [19] a category entry setting module, configured to set a category entry to record types of ONUs with different transmission rates; a gap allocation module, configured to perform uniform gap allocation on different transmission rate ONUs according to the foregoing entry, to form an uplink bandwidth allocation entry;

[21] The bandwidth allocation module is configured to carry the bandwidth allocation commands of different transmission rates ONUs to the corresponding downlink optical channels of different wavelengths according to the uplink bandwidth allocation entry.

[22] An embodiment of the present invention provides a method for determining an ONU downlink rate, including:

[23] During the discovery process, the discovery message sent to the specific downlink rate ONU is sent through the corresponding wavelength; [24] a dedicated discovery window for the ONU of the specific downlink rate is registered in the discovery window. ON U is determined to be an ONU having the specific downlink rate.

[25] An embodiment of the present invention provides an apparatus for determining an ONU downlink rate, including:

[26] The discovery packet sending module is configured to send the discovery message sent to the specific downlink rate ONU through the corresponding wavelength during the discovery process;

[0] The ONU downlink rate determining module is configured to set up a special discovery window for the ONU of the specific downlink rate, and determine an ONU registered in the discovery window as an ONU having the specific downlink rate.

An embodiment of the present invention provides a method for determining a discovery window to which a different rate ONU belongs, including:

[29] In the process of the discovery, the protocol packet corresponding to the discovery window is received from the ONU, where the protocol packet includes the identifier information, where the identifier information indicates a correspondence between the discovery window and the downlink rate.

[30] determining, according to the downlink rate of the ONU and the identifier information, a discovery window to which the ONU belongs.

An embodiment of the present invention provides an apparatus for determining a discovery window to which an ONU belongs to a different rate, including:

[32] The receiving module is configured to receive, according to the discovery process, a protocol packet corresponding to the discovery window, where the protocol packet includes the identifier information, where the identifier information indicates a correspondence between the discovery window and the downlink rate.

[33] The determining module determines, according to the downlink rate of the ONU and the identifier information, a discovery window to which the ONU belongs.

According to the foregoing technical solution, the embodiment of the present invention uses the OLT to manage the classification information of the ONU, and performs uniform gap allocation according to the classification information, thereby realizing the most efficient bandwidth allocation. The embodiment of the present invention achieves the following technical effects:

[35] 1) Resolved the bandwidth allocation in PON coexistence with different transmission rates;

[36] 2) Provides the most efficient method of bandwidth allocation in a coexisting PON.

Other features and advantages of the invention will be set forth in the description which follows, The objectives and other advantages of the invention will be realized and attained by the <RTI

[38] BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are set forth in the claims of the claims In the drawing: [1] FIG. 1 is a schematic structural diagram of a PON network system according to the prior art;

[2] FIG. 2 is a schematic diagram of a PON network in which a lOGbps and a lGbps ONU coexist according to the prior art;

FIG. 3 is a flow chart showing a method of determining an ONU downlink rate according to an embodiment of the present invention; FIG.

4 shows a block diagram of a device for determining an ONU downlink rate according to an embodiment of the present invention;

FIG. 5 is a flow chart showing a bandwidth allocation method for coexistence of different transmission rate PONs according to an embodiment of the present invention; FIG.

6 shows a block diagram of a bandwidth allocation apparatus for coexistence of different transmission rate PONs according to an embodiment of the present invention;

Figure 7 is a schematic diagram showing the switching between the lGbps and lOGbps transmission rate lasers, respectively, in accordance with one embodiment of the present invention;

Figure 8 is a diagram showing a comparison of the protection between messages between lGbps and lOGbps transmission rates in accordance with one embodiment of the present invention;

9 shows a schematic diagram of a comparison between different bandwidth allocation efficiencies according to an embodiment of the present invention; [49] FIG. 10 shows a flow chart of a method for determining a discovery window to which a different rate ONU belongs according to the present invention;

Figure 11 shows a block diagram of an apparatus for determining discovery windows to which different rate ONUs belong, in accordance with the present invention.

[51] Mode for carrying out the invention

The present invention will be described in detail below with reference to the drawings in conjunction with the embodiments.

[53] The embodiments of the present invention propose that, due to different downlink rates, ONUs such as lOGbps ONUs and lGbpss

The ONU uses different downstream wavelengths.

An embodiment of the present invention provides a method for determining an ONU downlink rate, including the following steps:

[55] Step S302: During the discovery process, the discovery packet sent to the specific downlink rate ONU is sent through the corresponding wavelength.

[0] Step S304, setting a special discovery window for the ONU of the specific downlink rate, and determining an ONU registered in the discovery window as an ONU having the specific downlink rate.

[57] For example, during the discovery process, the discovery message of the lOGbps ONU passes the corresponding wavelength such as 1550nm.

Wavelength is sent to lOGbps ONU, and one is designed for lOGbps

The discovery window of the ONU is set up, so as long as the ONUs registered in this discovery window are lOGbps ONUo, the discovery messages of the same lGbps ONU are sent to the lGbps through the corresponding wavelengths such as 1490nm wavelength. ONU, and open a dedicated for lGbps

The discovery window started by ONU, as long as the ONU registered in this discovery window is lGbps ONU.

4 shows an apparatus 400 for obtaining an ONU downlink rate according to an embodiment of the present invention, which includes:

[59] The discovery packet sending module 402 is configured to send the discovery packet sent to the specific downlink rate ONU through the corresponding wavelength during the discovery process;

[0] The ONU downlink rate determining module 404 is configured to set up a special discovery window for the ONU of the specific downlink rate, and determine an ONU registered in the discovery window as an ONU having the specific downlink rate.

[61] Optionally, the specific downlink rate includes 10 Gbps or 1 Gbps. The specific downlink rate is 10 Gbps, and the discovery module 402 is further configured to send the discovery packet to the 1550 nm wavelength. The discovery module 402 is further configured to send the discovery packet through a wavelength of 1490 ηm.

[62] Due to different uplink rates, ONUs such as lOGbps ONU and lGbps

The ONU uses the same upstream wavelength, and can set up a dual-mode or multi-mode receiver to identify the uplink rate of the ONU.

[63] FIG. 5 illustrates a bandwidth allocation method for coexistence of different transmission rate PONs according to an embodiment of the present invention, which includes the following steps:

[64] Step S502, setting a category entry in the OLT, for recording the type of the ONU of different transmission rates, and identifying the uplink transmission rate and the downlink transmission rate of the ONU according to the type;

[65] Step S504: The OLT performs unified gap allocation on different transmission rate ONUs according to the foregoing entry to form an uplink bandwidth allocation entry;

[66] Step S506, according to the uplink bandwidth allocation entry, respectively, the bandwidth allocation instructions of different transmission rates are respectively carried on the downlink optical channels of different wavelengths. The data sent to different downlink rate ONUs can also be placed at the wavelength corresponding to the downlink rate.

[67] Optionally, the different transmission rates ONU include a high transmission rate ONU and a low transmission rate ONU, and the category entries set in the OLT include two categories, a high transmission rate and a low transmission rate.

[68] Step S504 may include dividing the ONU into two groups according to different transmission rates, so that the high transmission rate ONU uplink buffers are adjacent, so that the low transmission rate ONU uplink gaps are adjacent.

[69] Optionally, the high transmission rate ONU is 10 Gbps ONU, and the low transmission rate ONU is 1 Gbps ONU. Step S504 includes the following steps: The bandwidth allocation instruction of the ONU of the 10 Gbps is sent to the ONU of the corresponding wavelength, such as the wavelength of 1 550 nm, to the ONU of the 10 Gbps, and the bandwidth allocation instruction of the ONU of the I Gbps is sent to the corresponding wavelength, such as the wavelength of 1490 nm, and sent to the IGbps. ONU.

FIG. 6 illustrates a bandwidth allocation apparatus 600 for coexistence of different transmission rate PONs according to an embodiment of the present invention, including:

The category entry setting module 602 is configured to set a category entry in the OLT to record the type of the ONU of different transmission rates, and according to the type, the uplink transmission rate and the downlink transmission rate of the ONU may be identified;

a gap allocation module 604, configured to enable the OLT to perform uniform gap allocation on different transmission rate ONUs according to the foregoing entry, to form an uplink bandwidth allocation entry;

The bandwidth allocation module 606 is configured to carry the bandwidth allocation commands of different transmission rates to the downlink optical channels of different wavelengths according to the uplink bandwidth allocation entry. The data sent to different downlink rates ON U can also be placed on the wavelength corresponding to the downlink rate.

Optionally, the different transmission rate ONUs include a high transmission rate ONU and a low transmission rate ONU, and the category entries set in the OLT include two types, namely a high transmission rate and a low transmission rate.

The gap allocation module 604 can be used to divide the ONU into two groups according to the transmission rate, so that the high transmission rate ONU uplink gaps are adjacent, so that the low transmission rate ONU uplink gaps are adjacent.

Optionally, the high transmission rate ONU is 10 Gbps ONU, and the low transmission rate ONU is 1 Gbps ONU.

The gap allocation module 604 can be used to allocate the bandwidth allocation command of the 10U ONU to the ONU of the 1OGbps at the wavelength of 1550 nm, and transmit the bandwidth allocation command of the IU ONU to the 1U Gbps ONU.

As can be seen from the above description, the present invention utilizes the OLT to manage the classification information of the ONU, and performs uniform gap allocation according to the classification information, thereby achieving the most efficient bandwidth allocation.

The OLT records the classification information of these ONUs in one entry, as shown in Table 1:

Table 1 Serial number transmission rate serial number

1 lOGbps 12654

2 lOGbps 25846

3 lGbps 98542 In the PON network shown in Figure 2, there are two ONUs with different transmission rates. The physical layer parameters of the optical modules have large differences, as shown in Table 2:

Table 2

[85]

Figure 7 shows a schematic diagram of the inter-turns of lGbps and lOGbps transmission rate lasers, respectively, in accordance with one embodiment of the present invention.

[87] Referring to FIG. 7, in a PON in which a high transmission rate and a low transmission rate ONU coexist, since two types of ONUs share the same uplink wavelength, it is necessary to uniformly perform gap allocation for ONUs of two transmission rates when performing bandwidth allocation. . In the process of allocating the gap, the difference in the physical parameters of the two ONUs is considered. For example, the laser recovery time of the lGbps ONU and the recovery time of the OLT are much slower than lOGbps. Therefore, the interval between uplink packets sent by different 1 Gbps ONUs is much larger than that of lOGbps.

[88] The role of protection between turns is that when the laser sends a message, it takes a while to turn off the laser. Before the laser is completely turned off, it still emits laser light, which interferes with the communication of other ONUs. And the laser of the ONU that sends the message later needs a certain time, and the laser will be emitted before the snoring, but the power cannot meet the normal communication requirements.

Figure 8 is a diagram showing a comparison of protection between messages between lGbps and lOGbps transmission rates in accordance with one embodiment of the present invention. Figure 9 shows a schematic diagram comparing the different bandwidth allocation efficiencies in accordance with one embodiment of the present invention.

[90] Referring to FIG. 8, since the laser of the ONU of the 1 Gbps is much longer than the 10 Gbps, if the 1 OGbps packet and the 1 Gbps packet are adjacent, lO Gbps The ONU waits for the IGbps ONU to completely turn off the laser to send the uplink signal, and the protection between the two is much longer than lOGbps. And for fast gain and clock recovery in the OLT, if the transmission rate and power change, the circuit response will take more time. Referring to Figure 9, if lOGbps

The uplink packets are grouped into one group. The uplink packets of IGbps are grouped into one group, which can greatly improve the allocation efficiency of the uplink bandwidth.

[91] After the OLT performs unified gap allocation on two different transmission rate ONUs, it forms a bandwidth allocation table, as shown in Table 3:

[92] Table 3

[93]

[94] According to the contents of this entry, the OLT transmits the bandwidth allocation command of the ONU of the lOGbps to the ONU of the lOGbps at the wavelength of 1550 nm. The bandwidth allocation command of the IGbps ONU is placed on the 1490nm wavelength and sent to the IGbps ONU.

An embodiment of the present invention further provides a method for determining a discovery window to which an ONU belongs at different rates. As shown in FIG. 10, the processing flow is as follows:

[96] Step S1002: Receive a protocol packet corresponding to the discovery window from the ONU, where the protocol packet includes the identifier information, where the identifier information indicates a correspondence between the discovery window and the downlink rate.

[97] Step S1004: Determine, according to the downlink rate of the ONU and the identifier information, a discovery window to which the ONU belongs.

An embodiment of the present invention further provides an apparatus for determining a discovery window to which an ONU belongs to different rates. As shown in FIG. 11, the method includes: The receiving module 1102 is configured to receive, according to the discovery process, a protocol packet corresponding to the discovery window from the ONU, where the protocol packet includes the identifier information, where the identifier information indicates a correspondence between the discovery window and the downlink rate.

[100] The determining module 1104 is configured to determine, according to the downlink rate of the ONU and the identifier information, a discovery window to which the ONU belongs.

[101] From the above description, it can be seen that the present invention achieves the following technical effects:

In the embodiment of the present invention, the ONU is configured to perform the gap allocation according to the uplink rate of the ONU, and the uplink bandwidth allocation entry is formed, so that the bandwidth allocation efficiency is high. According to the uplink bandwidth allocation entry, the bandwidth allocation instruction is used. The wavelength corresponding to the downlink rate of the ONU is sent to the ONU, so that the PON coexists at different rates, and the rate is matched with the bandwidth and the wavelength, so that the OLT is uniformly scheduled in the inter-turn, and the bandwidth allocation of the PON coexistence at different rates is formed. solution.

In the embodiment of the present invention, in the discovery process, the discovery packet sent to the specific downlink rate ONU is sent through the corresponding wavelength; a special discovery window is opened for the ONU of the specific downlink rate, and the subsequent The discovery window is registered, and the downlink rate of the ONU is determined to be the specific downlink rate, so that the downlink rate is obtained conveniently and quickly. In addition, in the embodiment of the present invention, the identifier information is used to indicate the corresponding relationship between the discovery window and the downlink rate. The subsequent discovery, according to the downlink rate of the ONU and the identifier information, may determine the discovery window to which the ONU belongs. A solution for opening different discovery windows for different rates of ON U is implemented.

[104] Obviously, those skilled in the art will appreciate that the various modules or steps of the present invention described above can be implemented with a general purpose computing device, which can be centralized on a single computing device or distributed across multiple computing devices. Optionally, they may be implemented by program code executable by the computing device, such that they may be stored in the storage device by the computing device, or they may be separately fabricated into individual integrated circuit modules, or Implementing multiple modules or steps in them as a single integrated circuit module. Thus, the invention is not limited to any specific combination of hardware and software. It is to be understood that changes in these specific embodiments will be apparent to those skilled in the art without departing from the scope of the invention.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes can be made to the present invention. Within the spirit and principles of the present invention Any modifications, equivalent substitutions, improvements, etc., are intended to be included within the scope of the present invention.

Claims

Claim

[1] 1. A bandwidth allocation method for coexistence of PONs with different transmission rates, comprising: setting a category entry in an OLT for recording types of ONUs of different transmission rates;

The OLT performs unified gap allocation on different transmission rate ONUs according to the foregoing entries to form an uplink bandwidth allocation entry;

According to the uplink bandwidth allocation entry, bandwidth allocation commands of different transmission rate ONUs are respectively carried on corresponding downlink optical channels of different wavelengths.

[2] The method according to claim 1, wherein the category entry set in the OLT includes a high transmission rate and a low transmission rate, and the different transmission rate ONU includes a high transmission rate ONU and a low Transmission rate ONU.

[3] The method according to claim 2, wherein the performing the uniform gap allocation comprises: grouping the ONUs according to different transmission rates, so that the high transmission rate ONUs are adjacent to each other, so that the low transmission rate is low. 0 NU upstream gaps are adjacent.

[4] The method according to claim 3, wherein the high transmission rate ONU includes an ONU of a transmission rate of 10 Gbps, and the low transmission rate ONU includes an ONU of a transmission rate of 1 Gbps.

[5] The method according to claim 4, wherein the performing the uniform gap allocation comprises: placing a bandwidth allocation instruction of the 10 Gbps ONU on the 1550 nm wavelength and transmitting the signal to the ONU of the 10 Gbps, and the ONU of the 1 Gbps Bandwidth allocation instructions are sent to the 1Unm ONU at 1490nm wavelength

[6] 6. A bandwidth allocation device for coexistence of different transmission rate PONs, comprising: a category entry setting module, configured to set a category entry to record types of ONUs of different transmission rates; a module, configured to perform uniform gap allocation on different transmission rate ONUs according to the foregoing entry, to form an uplink bandwidth allocation entry;

The bandwidth allocation module is configured to carry the bandwidth allocation commands of different transmission rate ONUs to the corresponding downlink optical channels of different wavelengths according to the uplink bandwidth allocation entry.

[7] The bandwidth allocation apparatus according to claim 6, wherein the set category entry includes a high transmission rate and a low transmission rate, and the different transmission rate ONU includes a high transmission rate ONU and a low transmission. Rate ONU.

[8] The bandwidth allocation device according to claim 7, wherein the gap allocation module is further configured to group the ONUs according to different transmission rates, so that the high transmission rate ONUs are adjacent to each other, so that the ONUs are low. The transmission rate ONU is adjacent to the upstream slot.

[9] The bandwidth allocation apparatus according to claim 8, wherein the high transmission rate ONU includes a 10 Gbps ONU, and the low transmission rate ONU includes an l Gbps ONU.

[10] The bandwidth allocation device according to claim 9, wherein the gap allocation module is further configured to send a bandwidth allocation instruction of an ONU of 10 Gbps to a wavelength of 1550 nm and send it to an ONU of 10 G bps, The bandwidth allocation command of the lGbps ONU is sent to the 1Ub ps ONU at the wavelength of 1490nm.

[11] 11. A method for determining an ONU downlink rate, comprising:

During the discovery process, the discovery packet sent to the specific downlink rate ONU is sent through the corresponding wavelength.

Dedicating a dedicated discovery window for the ONU of the specific downlink rate, and determining an ONU registered in the discovery window as an ONU having the specific downlink rate.

[12] The method according to claim 11, wherein the specific downlink rate comprises 10 Gb ps or 1 Gbps.

[13] The method according to claim 12, wherein the specific downlink rate is 10 Gbps, and the discovery packet is sent through a wavelength of 1550 nm.

[14] The method according to claim 12, wherein the specific downlink rate is 1 Gbps, and the discovery packet is sent through a wavelength of 1490 nm.

[15] 15. Apparatus for determining an ONU downlink rate, comprising:

The discovery packet sending module is configured to send the discovery packet sent to the specific downlink rate ONU through the corresponding wavelength during the discovery process;

The ONU downlink rate determining module is configured to set a special discovery window for the ONU of the specific downlink rate, and determine an ONU registered in the discovery window as an ONU having the specific downlink rate.

[16] 16. The apparatus according to claim 15, wherein the specific downlink rate comprises 10 Gb ps or 1 Gbps.

[17] 17. The apparatus according to claim 16, wherein the specific downlink rate is 10 Gbps The discovery module is further configured to send the discovery message through a wavelength of 1550 nm.

[18] The device according to claim 16, wherein the specific downlink rate is 1 Gbps, and the discovery module is further configured to send the discovery packet by using a wavelength of 1490 nm.

[19] 19. A method for determining a discovery window to which a different rate ONU belongs, comprising:

In the process of the discovery, the protocol packet corresponding to the discovery window is received from the ONU, where the protocol packet includes the identifier information, where the identifier information indicates the correspondence between the discovery window and the downlink rate; and the downlink rate and the identifier according to the ONU Information, determining the discovery window to which the ONU belongs.

[20] 20. An apparatus for determining a discovery window of a different rate ONU, characterized in that it comprises:

a receiving module, configured to receive a protocol packet corresponding to the discovery window from the ONU, where the protocol packet includes the identifier information, where the identifier information indicates a correspondence between the discovery window and the downlink rate;

The determining module determines, according to the downlink rate of the ONU and the identifier information, a discovery window to which the ONU belongs.