CN100590997C - An Overhead Processing Method for Service Multiplexing in OTN Network - Google Patents

Abstract

A kind of overhead processing method of business multiplexing in the OTN network that relates to digital information transmission, it adopts following steps: A, when low-speed business signal is mapped and multiplexed to OTN, divide the OPU payload area of OTN frame, B, in OPU overhead Indicates the division, allocation and related customer service type information of the OPU payload area in the area; the OPU payload area is divided into several time slots of the same size, and the payload structure corresponding to the multiframe alignment sequence MFAS is used to indicate PSI to indicate each Time slots are assigned to the information corresponding to the client port and the corresponding client service type; the OPU payload area is divided into several sub-blocks, and the payload structure corresponding to the multiframe alignment sequence MFAS is used to indicate that PSI indicates the client port and the corresponding client service type corresponding information, and use the OPU overhead area to indicate the sub-block location information of the corresponding customer service in the OPU payload area; the present invention provides an overhead processing method when multiple or arbitrary low-speed service signals are mapped and multiplexed into the OTN frame structure. The invention is simple, effective and highly operable.

Description

An Overhead Processing Method for Service Multiplexing in OTN Network

technical field

The invention relates to the transmission of digital information, in particular to an overhead processing method for service multiplexing in an OTN network.

Background technique

With the continuous growth of voice services and data services, the capacity of the transmission network is continuously increased, and the transmission bandwidth is also continuously improved. Transmission technology has mainly experienced several development stages such as PDH, SDH, and WDM. PDH technology mainly uses asynchronous multiplexing to increase transmission rate, SDH technology mainly improves transmission rate through synchronous multiplexing, and WDM technology mainly uses wavelength multiplexing. way to increase line transmission bandwidth.

At present, the network structure mainly adopts the network structure in which the data is processed by SDH and then mapped to WDM. For data services, it needs to be mapped and multiplexed by SDH before being sent to the WDM system for processing, and a signal with a fixed wavelength is generated for transmission in the optical fiber medium. For For voice services, high-speed SDH signals are formed through SDH synchronous multiplexing, and then mapped to the WDM system for wavelength multiplexing processing. This kind of network structure involves complex network layers, and introduces a large amount of additional overhead, resulting in high operating costs.

OTN (Optical Transport Network, Optical Transport Network) technology overcomes the defects of SDH and WDM technologies, and can transparently carry data, voice and other service signals. The OTN standard specifies three rate levels: 2.5G level OTU1/ODU1/OPU1, 10G level OTU2/ODU2/OPU2, 40G level OTU3/ODU3/OPU3, ITU-T G.709 standard specifies 2.5Gbps, 10Gbps , The mapping processing method of 40Gbps CBR signal to OTU1, OTU2 and OTU3, and also stipulates the multiplexing processing method of low-speed OTN (including ODU1, ODU2) signal to high-speed OTN (including OTU2, OTU3) frame structure.

The OTN standard has not specified how low-speed CBR signals such as OC-3/STM-1, OC-12/STM-16 and other SONET/SDH signals and data services are mapped and multiplexed into the OTN frame structure.

US Patent US 20030048813A1 (Optix Networks Inc.) specifies a method for mapping and multiplexing CBR (Constant Rate Bit Stream) signals into OTN frames. This patent draws on the multiplexing processing method from low-speed OTN signals to high-speed OTN frame structures , the payload part of the high-speed OTN frame is divided into multiple time slot groups, and each time slot group is allocated to different customers, wherein the overhead information related to each CBR customer is mapped to the OPU overhead area.

In summary, the prior art has the following deficiencies:

1. The above patent simply describes the use of the OPU (OpticalChannel Payload Unit) overhead area in the OTN frame structure to carry the overhead related to customer mapping processing, and does not specify how to handle the overhead. Overhead does not provide realistically effective means.

2. The above-mentioned patent does not describe how to map low-speed CBR signal, low-speed ODU (Optical Channel Data Unit, optical channel data unit) service and low-speed data signal mixed service to OTN for transmission.

3. For the OTN standard and the above patents, they are limited to the overhead processing of low-speed CBR signal and low-speed ODU signal mapping and multiplexing that have a fixed relationship with the bandwidth of the OPU payload area, and lack of low-speed service signal mapping and multiplexing for any bandwidth. overhead processing.

Contents of the invention

The purpose of the present invention is to provide an overhead processing method for business multiplexing in an OTN network, providing multiple low-speed business signals or their mixed business signals, and the low-speed business signals including any bandwidth when they are mapped and multiplexed to the OTN frame structure The overhead processing method is used to easily and effectively realize low-speed service signal mapping and multiplexing overhead processing of any bandwidth.

The overhead processing method of service multiplexing in the OTN network adopted by the present invention adopts the following steps:

A. When low-speed service signals are mapped and multiplexed to OTN, the OPU payload area of the OTN frame is divided, and the OPU payload area is divided into several time slots of the same size;

B. In the OPU overhead area, the payload structure corresponding to the multiframe alignment sequence MFAS is used to indicate that the PSI indicates the information of allocating each time slot to the corresponding client port and the corresponding client service type.

In the described step A, each of the time slots is arranged in order of sequence number in the OPU payload area, and is fixedly located in the OPU payload area;

In the described step A, each time slot described adopts the mode of TDM time division multiplexing in the OPU payload area, and is fixedly positioned in the OPU payload area by serial number;

In the described step B, the described payload structure indicates that the PSI byte is divided into two sections, which respectively represent the corresponding customer service type and the allocated customer port of the relevant time slot;

Use the value of the multiframe alignment sequence MFAS to specify the corresponding time slot to indicate the rate adjustment for the client service corresponding to the time slot;

The mode of assigning the PSI cyclic value to the payload structure indication is used to indicate the rate adjustment of the client service corresponding to a specific time slot.

In the described step A, when dividing the OPU payload area of the OTN frame, the OPU payload area is divided into several sub-blocks; in the described step B, in the OPU overhead area, adopt the multiframe alignment sequence MFAS corresponding The payload structure instruction PSI indicates the corresponding information of the client port and the corresponding client service type, and uses the overhead bytes in the OPU overhead area to indicate the sub-block position information of the corresponding client service in the OPU payload area;

The sub-block location information of the client service in the OPU payload area is indicated by three reserved words in the OPU overhead area;

Indicates the sub-block position of a specific customer service in the OPU payload area by indicating the PSI cyclic assignment to the payload structure;

Using the method of indicating PSI cyclic assignment to the payload structure indicates that the rate adjustment is performed on a specific client service;

Use the value of the multiframe alignment sequence MFAS to specify the corresponding customer service, indicating that the rate adjustment of the customer service is performed;

The low-speed service signal is a low-speed CBR signal, a low-speed ODU signal, a low-speed data signal, or a mixture of multiple signals;

For the low-speed CBR signal or low-speed ODU signal, it is necessary to judge whether to use asynchronous mapping, which is determined by the adjustment control byte JC (Justification Control), the negative adjustment opportunity byte NJO (Negative Justification Opportunity), and the positive adjustment opportunity in the OPU overhead area. Byte PJO (Positive Justification Opportunity) for corresponding adjustment control.

The beneficial effects of the present invention are: in the present invention, when the low-speed service signal is mapped and multiplexed to the OTN, the OPU payload area of the OTN frame is divided into time slots or sub-blocks, and the division of the OPU payload area is indicated in the OPU overhead area , assignments, and related customer business type information.

For the overhead processing of low-speed service signal mapping and multiplexing to OTN frames that have a fixed relationship with the bandwidth of the OPU payload area, the payload structure is used to indicate that PSI indicates that each time slot is allocated to the corresponding client port and the corresponding client service type. Divide the PSI byte of the payload structure indication into two sections, which respectively represent the customer service type corresponding to the relevant time slot and the allocated customer port, which provides a simple and effective means for processing overhead.

For the overhead processing of mapping low-speed service signals with any bandwidth and multiplexing them into OTN frames, the payload structure is used to indicate that PSI indicates the corresponding information of the customer port and the corresponding customer service type, and the three reserved words in the OPU overhead area are used to indicate the corresponding customer The sub-block location information of the service in the OPU payload area has a simple processing method and strong operability. In this way, a fixed payload area division method is not required, and the corresponding relationship between the OPU payload area and the client port is carried by the OPU overhead.

In the present invention, the division situation of OPU payload area (this division can be divided for the fixed time slot of fixed bandwidth; Also can according to customer service port, different bandwidth is allocated to the customer service of different bandwidth, use OPU net The start and end positions of the load area), the allocation of different areas to customer service ports, and the information of different customer service types are indicated in the OPU overhead area. According to the OPU overhead indication, the time slots contained in the OPU payload area can be obtained The number of customer service ports connected, the customer service type information of different ports, and the location information of the customer service in the OPU payload area. Based on these information, the customer service signal is extracted. For low-speed CBR or low-speed ODU services, also The customer service can be adjusted accordingly according to the adjustment control overhead instruction, and the receiving end can use the corresponding overhead information in the OPU overhead area to directly extract the signal belonging to each client port from the payload area, which is convenient for signal recovery and does not need to be received terminal to configure.

In a word, the present invention provides multiple low-speed service signals or their mixed service signals, and an overhead processing method when low-speed service signals including any bandwidth are mapped and multiplexed into the OTN frame structure, and the implementation method is simple, effective and highly operable .

Description of drawings

FIG. 1 is a schematic diagram of an OTN frame structure;

Fig. 2 is a schematic diagram of OPU overhead structure;

Fig. 3 is the correspondence table of adjustment overhead bytes;

Fig. 4 is a schematic diagram of payload structure indication PSI byte division;

Fig. 5 is a schematic diagram of OPU1 time slot division and allocation of corresponding client ports;

Fig. 6 is a schematic diagram of OPU1 time slot division and allocation of corresponding client ports;

Fig. 7 is a schematic diagram of the allocation of time slots to client ports and the assignment of corresponding OPU overhead;

Figure 8 is a schematic diagram of the start column and end of the customer service indicated by using three reserved words in the OPU overhead area;

Fig. 9 is a schematic diagram of payload structure indicating PSI byte and reserved word allocation;

Fig. 10 is a schematic diagram of the payload and overhead allocation of two STM-4 plus one GbE mapped and multiplexed into OPU1.

Detailed ways

Below according to accompanying drawing and embodiment the present invention will be described in further detail:

The OTN proposal stipulates three frame structures with different rates, which are OTU1/ODU1/OPU1 at the 2.5G rate level, OTU2/ODU2/OPU2 at the 10G rate level, and OTU3/ODU3/OPU3 at the 40G rate level. For OTN frames of each rate, the size of the frame structure is exactly the same, and the transmission rate is different. For example, for OTU1/ODU1/OPU1 frames, the frame period is about 48us, while the frame period of OTU2/ODU2/OPU2 is about 12us, OTU3/ The frame period of ODU3/OPU3 is about 3us.

As shown in Figure 1, the G.709 recommendation stipulates that the structure of the OTN frame is a block byte structure with 4 rows and 4080 columns, of which the first 16 columns are the OTN overhead area, and the 17th to 3824th columns are the payload area. Between 3825 and 4080 columns is the forward error correction FEC (Forward Error Correction) overhead area.

The OPU overhead area is shown in Figure 2. The 16th column of the 1st to 3rd row is the adjustment control byte JC, the 4th row and the 16th column are the negative adjustment opportunity byte NJO, and the 4th row and the 17th column are the positive adjustment opportunity byte. The sections PJO, JC and NJO, PJO form the adjustment control overhead, which is used to adapt the frequency deviation between the client signal and the OTN frame signal. The 4th row and the 15th column indicate the PSI byte of the OPU payload structure, which is the overhead related to the customer information mapped in the OPU frame structure.

As shown in Figure 2, the OPU overhead area contains overhead related to client signal mapping: the payload structure indicates PSI, and PSI is a 256-byte multiframe structure, where the meaning of each byte is determined by the value corresponding to the multiframe alignment sequence MFAS To define, the multiframe alignment sequence MFAS is 0 (decimal) corresponding to PT (payload type), and the G.709 standard specifies the mapping of different client signals to the OPU payload area, such as the payload in Table 1 Type code table shown. For example, for the asynchronous mapping of CBR signals (that is, Asynchronous CBR), this area is set to 0x02; PSI[1]~PSI[255] are specific overheads for mapping and concatenation. For the multiplexing of low-speed ODUj to high-speed ODUk (j<k) specified in G.709, the area corresponding to the multiframe alignment sequence MFAS 1 is reserved bytes; the area corresponding to the multiframe alignment sequence MFAS 2~17 To indicate the MSI for the multiplexing structure, the MSI area contains the multiplexing structure information of the low-speed ODUj tributary signal in the high-speed OPUk signal. According to the MSI indication, the position of the low-speed tributary signal in the OPU payload area can be determined. As shown in Figure 3, the OPU overhead area also includes adjustment overheads JC, NJO, and PJO for asynchronous mapping, where JC is the adjustment control byte, and it is the bits 7 and 8 of the JC byte that work, and NJO is the negative adjustment opportunity Byte, if the client signal rate is greater than the OPU frame rate, fill the byte area with data bytes, PJO is the positive adjustment opportunity byte, when the client signal rate is lower than the OPU frame rate, fill the adjustment byte in this area; when When the client signal rate is equal to the OPU frame rate, the adjustment operation will not be performed, that is, the NJO byte is a stuffing byte, and the PJO byte is a data byte. In the mapping direction from the client signal to the OPU frame, JC, NJO, and PJO information are generated according to this rule, and the demapping direction from the OPU frame to the client signal is based on the information of bits 7 and 8 of the received JC byte. The 3:2 majority decision rule extracts the corresponding information from NJO and PJO.

MSB1 2 3 4 LSB5 6 7 8 Hexadecimal code type 0 0 0 0 0 0 0 1 01 Experimental mapping 0 0 0 0 0 0 1 0 02 Asynchronous CBR mapping 0 0 0 0 0 0 1 1 03 Bit synchronous CBR mapping 0 0 0 0 0 1 0 0 04 ATM mapping 0 0 0 0 0 1 0 1 05 GFP mapping 0 0 0 0 0 1 1 0 06 Virtual Concatenated signal 0 0 0 1 0 0 0 0 10 Bit stream with octet timing mapping 0 0 0 1 0 0 0 1 11 Bit stream without octet timing mapping 0 0 1 0 0 1 1 0 20 ODU multiplex structure 0 1 0 1 0 1 0 1 55 Not available 0 1 1 0 0 1 1 0 66 Not available 1 0 0 0 x x x x 80-8F Reserved codes for proprietary use

1 1 1 1 1 1 0 1 FD NULL test signal mapping 1 1 1 1 1 1 1 0 FE PRBS test signal mapping 1 1 1 1 1 1 1 1 FF Not available

Table 1

The present invention uses the PSI information of the OPU overhead area to indicate the division and allocation of the OPU payload area and related customer service type information. The present invention adopts the principle of the PSI byte allocation of existing G.709, utilizes PT (being PSI[0] position) to be the value of binary 1000xxxx, namely the hexadecimal value 0x80～0x8F section, and indicates the OPUk payload area Carry multiple arbitrary low-speed service signals. The PT can be specified as any fixed value between 0x80 and 0x8F (assumed to be 0x80), indicating that the OPU payload area carries multiple low-speed service signals.

According to the situation of multiplexed low-speed customer services, for specific low-speed customer services, the bandwidth between customer services has a fixed relationship, and has a certain relationship with the bandwidth of the OPU payload area, such as a multiple relationship in a certain sense. The time slot division method realizes the multiplexing of low-speed customer services to the OPU payload area. ITU-T G.709 also adopts this allocation method of fixed time slot division to realize the multiplexing from low-speed ODU1/ODU2 to OPU2/OPU3, although the rate of ODU1/ODU2 is not a strict multiple relationship, and their rate is the same as that of OPU2/ The bandwidth of the payload area of OPU3 is not a strict multiple relationship, but this processing allows a single low-speed service to cross multiple high-speed OPU signals. This bandwidth allocation scheme is suitable for multiplexing the low-speed CBR service/low-speed ODU service into the high-speed OPU payload area. For example, one or more mixed services of CBR155/CBR622/CBR2.5G/CBR10G/ODU1/ODU2 are multiplexed into the high-order OPU payload area. At this time, the OPU payload area of the OTN frame is divided into several time slots of the same size. In the OPU overhead area, the PSI information corresponding to the multiframe alignment sequence MFAS is used to indicate that each time slot is allocated to the corresponding client port and Information on the corresponding customer business type.

As shown in Figure 4, N represents the maximum number of time slots in the OPU payload area, i represents a certain time slot, 1≤i≤N; k represents the number of client ports, 0≤k≤N.

The value of PSI[0] indicates that the OPU payload area bears multiple low-speed services, and it is set to a value between 0x80 and 0x8F. PSI[1] indicates the number of time slots in the OPU payload area, and the value is N. PSI[i+1] (1≤i≤N) indicates which client port is assigned to the i-th time slot and the client service type. PSI[i+1] indicates the type of client service and the time slot information of the OPU payload area occupied by the client service. It can be allocated in this way. The low 4-bit indicates which client port the i-th time slot is assigned to. The value of this area indicates the serial number of the client port. The high 4-bit of PSI[i+1] is the customer service type area. Different customers Businesses correspond to different values. As shown in Figure 4, the high 4-bit customer service type area of PSI[i+1] corresponds to the corresponding low 4-bit customer port as follows:

0000: ODU1 0000: Client port 1

0001: ODU2 0001: Client port 2

0010: OC-3/STM-1 0010: Client port 3

0011: OC-12/STM-4 0011: Client Port 4

0100: OC-48/STM-16

0101: OC-192/STM-64…

... 1111: client port 16

Other: reserved

With these two parts of information, it can be judged which client port the time slot is allocated to. At the receiving end, according to this information, the information extracted from the OPU payload area is sent to different client service port processing modules to ensure correct Restore client business signals. At the same time, the customer service type accessed by the customer port can also be obtained.

You can also use PSI[N*j+i+1] and PSI[i+1] to define the same cyclic assignment, that is, PSI[N*j+i+1] and PSI[i+1] take the same value . Wherein, 1≤i≤N, 0≤j≤[254/N]-1 ([254/N] is the integer part of N divided by 254), and j represents the maximum cycle number of time slot allocation. For example, if N=16, then i=1-16, j=0-14. Then assign the PSI byte positions of the 2nd OTN frame, the 18th OTN frame, the 32nd OTN frame, ..., the 226th OTN frame in the multiframe to the client port corresponding to the first time slot and the corresponding client Service type: assign the PSI byte positions of the 17th OTN frame, the 33rd OTN frame, ..., the 241st OTN frame in the multiframe to the client port corresponding to the 16th time slot and the corresponding client service type. If the value of the lower 4-bit of PSI[i+1] is k, it means that the i-th time slot is allocated to the (k+1)th client port, and the value of the upper 4-bit of PSI[i+1] Indicates the service type of the kth client port; the value of PSI[N*j+i+1] also includes the allocation of the same time slot to the client port and the corresponding client service type information.

Here is an example of a practical application: For the multiplexing of 3 STM-4 plus 4 STM-1 customer service signals into the OPU1 frame structure, the situation is as follows:

The client ports are sorted as:

Client port #1: STM-4#1; Client port #2: STM-1#1;

Client port #3: STM-1#2; Client port #4: STM-4#2;

Client port #5: STM-1#3; Client port #6: STM-4#3;

Client port #7: STM-1#4.

In this case, because the bandwidth of the customer service signal has a multiple relationship, that is, the STM-4 customer service bandwidth is 4 times that of the STM-1 customer service bandwidth, so the OPU1 payload part can be divided into 16 time slots (corresponding to the time slot Slot #1 to #16), each time slot has a bandwidth of STM-1.

As shown in FIG. 5 , the time slots are arranged in sequence in the OPU payload area and fixedly located in the OPU payload area.

As shown in FIG. 6 , each time slot adopts TDM time division multiplexing in the OPU payload area, and is fixedly located in the OPU payload area according to the sequence number.

As shown in Figure 5 and Figure 6, the allocation relationship between the given time slots and client ports is:

Time slot #1～time slot #4 is assigned to STM-4#1 of client port #1;

Time slot #5 is assigned to STM-1#1 of client port #2;

Time slot #6 is assigned to STM-1#2 of client port #3;

Time slot #7～time slot #10 is assigned to STM-4#2 of client port #4;

Time slot #11 is assigned to STM-1#3 of client port #5;

Time slot #12～time slot #15 is assigned to STM-4#3 of client port #6;

Time slot #16 is assigned to STM-1#4 of client port #7.

In this way, as shown in Figure 7:

The time slots corresponding to PSI[2]~PSI[5] are allocated to the STM-4 service of client port #1,

Then the value of PSI[2]～PSI[5] is 0011 0000;

The time slot corresponding to PSI[6] is assigned to the STM-1 service of client port #2,

Then the value of PSI[6] is 0010 0001;

The time slot corresponding to PSI[7] is assigned to the STM-1 service of client port #3,

Then the value of PSI[7] is 0010 0010;

The time slots corresponding to PSI[8]~PSI[11] are allocated to the STM-4 service of client port #4,

Then the value of PSI[8]～PSI[11] is 0011 0011

The time slot corresponding to PSI[12] is assigned to the STM-1 service of client port #5,

Then the value of PSI[12] is 0010 0100;

The time slots corresponding to PSI[13]~PSI[16] are allocated to the STM-4 service of client port #6,

Then the value of PSI[13]～PSI[16] is 0011 0101;

The time slot corresponding to PSI[17] is assigned to the STM-1 service of client port #7,

Then the value of PSI[17] is 0010 0110.

If the corresponding customer service type is a low-speed CBR signal or a low-speed ODU signal, it is necessary to judge whether to use asynchronous mapping for rate adjustment. At this time, the adjustment control byte JC, negative adjustment opportunity byte NJO, and positive adjustment in the OPU overhead area The opportunity byte PJO adjusts the control accordingly. The adjustment control adopts the method stipulated in the G.709 standard, refer to Figure 3. Here it is only described how to use overhead to indicate which time slot is to be adjusted and controlled.

For the case where the rate adjustment of the accessed client service is required, the value of the multiframe alignment sequence MFAS can be used to specify the corresponding time slot to indicate the rate adjustment of the client service corresponding to the time slot. For example, in the case of dividing 4 time slots, you can use the 2-bit bit [78] of MFAS to indicate that the customer service corresponding to one of the time slots #1 to #4 is adjusted; for 16 time slots In the case of division, use MFAS bit[5678], a total of 4-bits, to indicate that the customer service corresponding to one of the time slots #1 to #16 is adjusted, and so on.

A method of assigning a PSI cyclic value to the payload structure indicator may also be used to indicate that the rate adjustment is performed on the client service corresponding to a specific time slot. With reference to the above-mentioned Fig. 4 and related explanations, use the mode of PSI[N*j+i+1] cyclic assignment to indicate that the corresponding customer service of a specific time slot is adjusted, then the (N*j+i +1) OTN frame can adjust the client service assigned to the i-th time slot. For example, if there are 4 customer services and 16 time slots, N=16, i=1~16, j=0~14, then the second OTN frame, the 18th OTN frame, and the 34th OTN frame in the multiframe OTN frame, ..., the 226th OTN frame can adjust the customer service corresponding to the first time slot, and use JC, NJO, PJO and other adjustment control overheads to process; and the 17th OTN frame in the multiframe, the 33rd OTN frames, ..., the 241st OTN frame can adjust the customer service corresponding to the 16th time slot, and use JC, NJO, PJO and other adjustment control overheads for processing.

In the above-mentioned practical application example, it is suitable for the situation that the time slot division of the OPU payload area is fixed, that is, the OPU payload area is divided according to certain rules, and are respectively labeled as time slot #1, time slot #2, ..., time slot Slot #N, each time slot is in a fixed position in the OPU payload area. At this time, as long as the serial number of the time slot is obtained, it can be determined which part of the payload area in the OTN frame structure the corresponding customer service occupies, reflecting the The invention relates to (mixed) low-speed service signals that have a fixed relationship between bandwidths and have a certain relationship with the bandwidth of the OPU payload area, such as low-speed CBR signals, low-speed ODU signals, low-speed data signals, or a mixture of multiple signals therein, etc. The division and allocation of the OPU payload area and the OPU overhead processing method adopted.

When the customer service signals of any bandwidth are mixed and multiplexed into the OTN frame structure, the OPU payload area of the OTN frame is divided into several sub-blocks, and each sub-block occupies a certain number of OPU payload columns. In the OPU overhead area, use The payload structure corresponding to the multiframe alignment sequence MFAS indicates that PSI indicates the corresponding information of the client port and the corresponding client service type, and uses the three reserved words RES1, RES2 and RES3 in the OPU overhead area to indicate that the corresponding client service is in the OPU payload area The sub-block position information of the sub-block, as shown in Figure 2, the three reserved words RES1, RES2 and RES3 in the first row, second row and third row in the 15th column, so that the position of the customer service in the OPU payload area It can be accurate to the column. The OPU payload area has a total of 3080 columns. As shown in Figure 8, it can be represented by a 12-bit length. Therefore, these three bytes can indicate that the customer service occupies the start column of the OPU payload area. and end columns.

The relevant overhead can be allocated in the following way: PSI[0] with MFAS value of 0, that is, PT, still indicates that multiple low-speed service signals are contained in the OPU payload area, and the value is a value from 0x80 to 0x8F; The OPU overhead PSI[1] of the OTN frame of 1 indicates the number N of client ports contained in the OPU payload area (supporting the access of a maximum of 254 client service signals), as shown in Figure 9, N indicates the number of client ports, and the MFAS value is used PSI[i+1] (1≤i≤N) corresponding to (i+1) represents the customer service type information corresponding to the i-th customer port, and the relevant information is set as follows:

PSI[2] 0000 0000: ODU1

PSI[3] 0000 0001: ODU2

... 0000 0010: OC-3/STM-1

0000 0011: OC-12/STM-4

0000 0100: OC-48/STM-16

0000 0101: OC-192/STM-64

0000 1000: GbE

0000 1001: FC100

At this time, the three reserved words RES1, RES2 and RES3 in the OPU overhead area indicate that the client service occupies the sub-block position of the OPU payload area.

You can also use PSI[N*j+i+1] overhead to indicate the customer service type corresponding to the i-th customer port, where 1≤i≤N, 0≤j≤[254/N]-1([254/N] is the integer part of N divided by 254), at this time, the combination of the low 4 bits of RES2 and the 8 bits of RES1 in the OPU overhead area indicates the start column of the customer service, and the combination of the 8 bits of RES3 and the high 4 bits of RES2 indicates the end column of the customer service.

For example, if 4 customer services are connected, the value of N is 4, that is, the OPU payload area is divided into 4 sub-blocks, the value of i is 1 to 4, and the value of j is 0 to 62, then PSI[2 ], PSI[6], ..., PSI[250] values indicate the first customer service type, and the corresponding RES3~RES1 values indicate the first customer service, that is, the end position of the corresponding sub-block in the OTN frame structure and Start position; ...; PSI[5], PSI[9], ..., PSI[253] position indicates the fourth customer service type, and the corresponding RES3~RES1 positions indicate the end of the fourth customer service in the OTN frame structure position and start position.

This cyclic assignment method can be used to indicate the rate adjustment of a specific customer service. If the corresponding customer service is a low-speed CBR or low-speed ODU service, it can be determined whether it needs to be set in PSI[N*j+i +1] The OTN frame corresponding to the i-th customer service is adjusted, and the adjustment process adopts the method specified in the G.709 standard.

The method of using PSI[N*j+i+1] to cyclically specify each customer service can ensure that the adjustment cycle for low-speed CBR or low-speed ODU customer services is small, and there is an adjustment opportunity every N frames, otherwise, it may need to go through It takes 256 frames to perform an adjustment operation on a customer service. The method of adjusting according to this cyclic assignment can compensate the frequency offset difference within the range specified by the standard.

Similarly, the value of the multiframe alignment sequence MFAS can also be used to specify the corresponding customer service to indicate that the rate adjustment of the customer service can be performed. For example, in the case of accessing 4 customer services, according to the value of bit[78] of MFAS Determine which client service is to be adjusted for rate. When the client service is a low-speed CBR signal or a low-speed ODU signal, it is necessary to determine whether to use asynchronous mapping. The adjustment control byte JC, negative adjustment opportunity byte NJO, and The positive adjustment opportunity byte PJO is adjusted accordingly.

Using this overhead processing method, the mapping and multiplexing processing of up to 254 different customer services to OTN frames can be realized, including CBR services of different customers, low-speed ODU services of different customers, data services of different customers, and CBR of different customers Mixed multiplexing and mapping of services, low-speed ODU services and data services, it is not limited by the division of OPU payload areas, and is not limited by the bandwidth of accessed customer services.

Another practical application example is as follows: For the mapping and multiplexing of two STM-4 plus one GbE customer service signals to the OPU1 payload area, the situation is as follows:

According to the bandwidth requirements of different client ports, the payload area of the OPU is divided into three sub-blocks (sub-block #1 to sub-block #3), divided according to the number of client service ports, and the payload area belonging to each client service port Defined as sub-blocks, the bandwidth size of each sub-block is not limited. For STM-4, the corresponding sub-block occupies 952 columns, and for GbE services, the corresponding sub-block occupies 1904 columns. The sub-block division of the OPU payload area, the start and end positions of the OPU payload area occupied by each client port, and the service type information of each client are shown in FIG. 10 .

Client port #1 is STM-4, occupying 952 columns between the 17th and 968th columns:

The initial location value of client port #1 should be 0000 0001 0001;

The end position value should be 0011 1100 1000;

Therefore, RES1, RES2, and RES3 are 0x11, 0x80, and 0x3C, respectively.

Client port #2 is STM-4, occupying 952 columns between columns 969 and 1920:

The initial location value of client port #2 should be 0011 1100 1001;

The end position value should be 0111 1000 0000;

Therefore, RES1, RES2, and RES3 are 0xC9, 0x03, and 0x78, respectively.

Client port #3 is GbE, occupying 1904 columns between 1921 and 3824 columns:

The initial location value of client port #3 should be 0111 1000 0001;

The end position value should be 1110 1111 0000;

Therefore, RES1, RES2, and RES3 are 0x81, 0x07, and 0xEF, respectively.

For OTN frames with MFAS values of (3*j+1+1), (3*j+2+1) (0≤j≤83), the corresponding RES3~RES1 and PSI[3*j+1+1] , PSI[3*j+2+1] overhead areas are respectively used to bear the position of the first STM-4 and the second STM-4 customer service in the OPU1 payload area and the customer service type information. At this time, they can be respectively Adjust the mapping of the first STM-4 and the second STM-4 customer service to the OPU payload area to compensate for the frequency deviation between the STM-4 service and the OTN frame; the MFAS value is (3*j+ 3+1) The RES3-RES1 and PSI[3*j+3+1] overhead areas of the corresponding OTN frame are used to carry the location of the GbE client service in the OPU1 payload area and the client service type information.

Claims (15)

1. an overhead processing method for business multiplexing in an OTN network, characterized in that: it adopts the following steps: A. When low-speed service signals are mapped and multiplexed to OTN, the OPU payload area of the OTN frame is divided, and the OPU payload area is divided into several time slots of the same size; B. In the OPU overhead area, the payload structure corresponding to the multiframe alignment sequence MFAS is used to indicate that the PSI indicates the information of allocating each time slot to the corresponding client port and the corresponding client service type. 2. the overhead processing method of service multiplexing in the OTN network according to claim 1, is characterized in that: in described step A, described each time slot is arranged in order of serial number in the OPU payload area, is fixedly positioned at In the OPU payload area. 3. the overhead processing method of service multiplexing in the OTN network according to claim 1, is characterized in that: in described step A, each described time slot adopts the mode of TDM time division multiplexing in the OPU payload area , fixedly located in the OPU payload area according to the serial number. 4. the overhead processing method of service multiplexing in the OTN network according to claim 1, is characterized in that: in described step B, described payload structure indication PSI byte is divided into two sections, represents relevant The customer service type corresponding to the time slot and the allocated customer port. 5. according to the overhead processing method of service multiplexing in the OTN network described in claim 1 or 2 or 3 or 4, it is characterized in that: adopt the value designation corresponding time slot of multi-frame alignment sequence MFAS, represent that this time slot Adjust the rate of the customer service corresponding to the slot. 6. The overhead processing method of service multiplexing in the OTN network according to claim 1 or 2 or 3 or 4, characterized in that: the mode of indicating the PSI cyclic assignment to the payload structure is used to represent a specific time slot The rate of the corresponding customer service is adjusted. 7. The overhead processing method of service multiplexing in the OTN network according to claim 1, characterized in that: the low-speed service signal is a low-speed CBR signal, a low-speed ODU signal, a low-speed data signal, or multiple signals wherein mix. 8. the overhead processing method of service multiplexing in the OTN network according to claim 7, is characterized in that: for described low-speed CBR signal or low-speed ODU signal, need to judge whether to adopt asynchronous mapping, by the adjustment in the OPU overhead area Control byte JC, negative adjustment opportunity byte NJO, and positive adjustment opportunity byte PJO perform corresponding adjustment control. 9. An overhead processing method for business multiplexing in an OTN network, characterized in that: A. When low-speed service signals are mapped and multiplexed to OTN, the OPU payload area of the OTN frame is divided, and the OPU payload area is divided into several sub-blocks; B. In the OPU overhead area, use the payload structure corresponding to the multiframe alignment sequence MFAS to indicate that PSI represents the corresponding information of the client port and the corresponding client service type, and use the overhead byte in the OPU overhead area to indicate that the corresponding client service is in the OPU Sub-block location information in the payload area. 10. The overhead processing method of service multiplexing in the OTN network according to claim 9, characterized in that: the sub-block position information of the customer service in the OPU payload area is indicated by three reserved words in the OPU overhead area . 11. the overhead processing method of service multiplexing in the OTN network according to claim 9, it is characterized in that: adopt the mode of PSI cyclic assignment to payload structure indication, represent the specific customer service in the OPU payload area subblock location. 12. The overhead processing method of service multiplexing in the OTN network according to claim 9 or 10 or 11, characterized in that: the method of using the payload structure to indicate PSI cyclic assignment indicates that a certain specific customer service Make rate adjustments. 13. The overhead processing method of service multiplexing in the OTN network according to claim 9 or 10 or 11, characterized in that: the value of the multiframe alignment sequence MFAS is used to specify the corresponding customer service, indicating that the customer service is performed rate adjustment. 14. The overhead processing method of service multiplexing in OTN network according to claim 9, characterized in that: the low-speed service signal is a low-speed CBR signal, a low-speed ODU signal, a low-speed data signal, or multiple signals therein mix. 15. The overhead processing method of service multiplexing in the OTN network according to claim 14, characterized in that: for the low-speed CBR signal or the low-speed ODU signal, it is necessary to judge whether to use asynchronous mapping, and the adjustment in the OPU overhead area Control byte JC, negative adjustment opportunity byte NJO, and positive adjustment opportunity byte PJO perform corresponding adjustment control.

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