CN1543162A - Method and adaptation device for mixed transmission of variable-length data packets and fixed-length cells - Google Patents

Abstract

The invention discloses a method and an adaptation device for mixed transmission of variable-length data packets and fixed-length cells. The method and the adaptation device complete the mapping between the variable-length data packet and the unified framing protocol unit UFPDU, the fixed-length cell and the modified asynchronous transfer mode ATM cell, and the unified framing protocol unit UFPDU and the modified asynchronous transfer mode ATM Cells are processed in the same virtual container/virtual tributary VC/VT or Transmission over bare fiber/cable. The header of the unified framing protocol data unit UFPDU is compatible with the ATM header of the asynchronous transfer mode, and the transmission of variable-length data packets adopts connection or connectionless mode. The invention not only greatly improves the transmission efficiency of synchronous digital system/synchronous optical network SDH/SONET or bare optical fiber/cable, but also provides identification and priority of high-level data protocols, and can provide variable-length data packets and fixed-length information for relevant network equipment. Metatransfer interface.

Description

Method and adaptation device for mixed transmission of variable-length data packets and fixed-length cells

Technical field:

The invention relates to related data transmission in information network. In particular, it involves mixed transmission of variable-length data packets and fixed-length cells on the same virtual container/virtual branch VC/VT or bare optical fiber/cable of the synchronous digital system/synchronous optical network SDH/SONET transmission line. The PDU method and adaptation device can provide packet transmission interfaces for relevant information network equipment, such as asynchronous transfer mode ATM interface and Ethernet medium independent interface MII.

Background technique:

In various transmission systems and information networks, network endpoints use synchronous digital system/synchronous optical network SDH/SONET equipment to complete the transmission of variable-length packets or asynchronous transfer mode ATM cells. Variable-length data packets (Internet Protocol IP packets, Ethernet media access control MAC frames, etc.) are encapsulated into PPP protocol data units PDU through point-to-point protocol PPP, and the protocol data unit (PPP PDU) is then controlled by advanced data link HDLC (or through the link access procedure LAPS on SDH, or through the general framing procedure GFP) into corresponding protocol data units, and then in a virtual container/virtual branch VC of synchronous digital system/synchronous optical network SDH/SONET /VT to teleport. Variable-length data packets can also be processed by the ATM adaptation layer (AAL) in the asynchronous transfer mode ATM network, and then divided according to the fixed length, and assembled into an asynchronous transfer mode ATM cell together with the cell header, in the synchronous digital system/ It is transmitted in a virtual container/virtual tributary VC/VT of synchronous optical network SDH/SONET. Variable-length data packets can be encapsulated into variable-length protocol data units and asynchronous transfer mode ATM cells through the above-mentioned multiple technologies, and can also be transmitted on bare optical fibers/cables.

The main defect of the above-mentioned technology is that in a virtual container/virtual branch VC/VT of Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET or on bare optical fibers/cables, only variable-length protocol data units or asynchronous transfer mode ATM signals can be transmitted. One type of protocol data unit PDU in the unit, but cannot transmit two kinds of protocol data unit PDU at the same time, so that the transmission efficiency of synchronous digital hierarchy/synchronous optical network SDH/SONET or bare optical fiber/cable is low.

The ATM Forum (ATM Forum) defines the ATM-based frame transmission method FAST (Frame based ATM over SONET/SDH Transport, fb-fbatm-0151.000, July, 2000) on the synchronous digital system SDH, which is encapsulated by the ATM adaptation layer AAL protocol High-level user data grouping, but its main drawbacks are:

(1) The bearer user data is mainly encapsulated by the ATM adaptation layer AAL5, resulting in the unit to be transmitted at the link layer being an integer multiple of 48 bytes (excluding the 4/8 bytes of the cell header defined by the ATM Forum), or will be The transmission unit adds padding (Padding) to make it an integer multiple of 48 bytes;

(2) The 32-bit frame check sequence FCS is used in the FAST frame format, but in most cases, real-time services such as voice or video do not require this frame check protection;

(3) There is no clear mention of how to distinguish between the two protocol data units (PDUs) when mixed transmission of variable-length packets and ATM cells in asynchronous transfer mode;

(4) FAST does not provide a connectionless data transmission function similar to the Internet Protocol IP network;

(5) When the high-level data packet is long, FAST divides it into multiple FAST frames for transmission, but the sequence number and position of the packet will occupy 3 bytes of overhead, which is relatively large;

(6) The load priority (such as the priority of high-level data user services) is not provided in the protocol data unit PDU of FAST, so that the network forwarding node working in the connectionless mode cannot provide different services such as language/video and data. Forwarding and switching strategies cannot guarantee the quality of service (QoS) of real-time user services.

"System and method for mapping fixed-length packets and variable-length packets on SONET/SDH" (WO 0217543) proposed by SCOTT JAMES, WEN-LUNG CHEN, GORDON LEE by storing 4n cells of bytes (n is a positive integer ), map these asynchronous transfer mode ATM cell byte streams and variable-length data packets encapsulated with high-level data link control HDLC into a multi-frame Superframe composed of 4n virtual tributaries VT. The disadvantages of this scheme are: (1) variable-length packets and fixed-length packets adopt different encapsulations, which increases the complexity of the implementation of related transmission and switching equipment; (2) because switching equipment uses virtual channel identifiers/virtual path Symbol VPI/VCI realizes cell switching, and the use of advanced data link control HDLC frame can only realize point-to-point transmission, and it is impossible to use a switching unit to complete variable-length packet and fixed-length packet switching; (3) because n is variable, The multiframe structure is complex, and it increases the end-to-end transmission delay of ATM cells in asynchronous transfer mode.

Invention content:

The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, and propose a method for mixed transmission of variable-length data packets and fixed-length cells and an adaptation device thereof, which are used for realizing variable-length data packets and cells between network endpoints, and synchronously Hybrid transmission on the same virtual container/virtual tributary VC/VT or bare optical fiber/cable of digital hierarchy/synchronous optical network SDH/SONET.

The mixed transmission method of variable-length data packets and fixed-length cells for realizing the object of the present invention includes transmission processing in two directions of sending and receiving, as shown in FIG. 1 . The processing flow of this method is slightly different under the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET or bare optical fiber/cable transmission mode, in which:

The sending direction is carried out according to the following process described in Figure 1(a):

(1) Use standard media independent interface MII, asynchronous transfer mode universal test and operation interface UTOPIA and other interfaces to receive variable-length data frames and fixed-length cells from user terminals, transmission equipment, switches and other network components, and convert variable-length data The load part in the frame, that is, the variable length data packet, is stored in the sending packet first-in-first-out memory, and the cells are directly put into the sending cell first-in-first-out memory;

(2) Add control header and header extension and packet check sequence PCS to the variable-length data packet, encapsulate it into a unified framing protocol data unit UFPDU, and convert the fixed-length cell into a modified cell format at the same time. The header error control HEC field of the cell format can be used optionally;

(3) Add a "special flag F" between the unified framing protocol data unit UFPDU and the cell to distinguish the boundary between the two, so as to distinguish the boundary between different protocol data units PDU, and according to the quality of service QoS characteristics of the user business, the unified group Frame protocol data unit UFPDU and modified cells are mixed;

(4) Add padding protocol data unit PPDU to the mixed flow composed of "special flag F" and unified framing protocol data unit UFPDU and cells to ensure the rate of the four (namely F, UFPDU, ATM cell, PPDU) The sum is equal to the net transmission rate of the virtual container/virtual tributary VC/VT of the synchronous digital system/synchronous optical network SDH/SONET or the bare optical fiber/cable line to achieve rate adaptation;

(5) Transparency processing is performed on the unified framing protocol data unit UFPDU, cell, and padding protocol data unit PPDU, that is, the transmitted unified framing protocol data unit UFPDU, cell, and padding protocol data unit PPDU and other three protocol data In the unit PDU, the "special flag F" that appears is processed;

(6) In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, load or map the mixed stream composed of "special flag F", unified framing protocol data unit UFPDU, cell, and filling protocol data unit PPDU To the virtual container/virtual tributary VC/VT of the synchronous digital system/synchronous optical network SDH/SONET, and for the payload in the virtual container/virtual tributary VC/VT, a self-synchronizing scrambling code with a polynomial of x ⁴³ +1 is used Selectable scrambling is performed by the scrambler; in the bare optical fiber/cable transmission mode, only the self-synchronizing scrambler with the polynomial x ⁴³ +1 is used for the above mixed stream to perform optional scrambling;

(7) In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, add the segment overhead SOH and channel overhead POH of the synchronous digital system/synchronous optical network SDH/SONET frame to the scrambled payload to form a synchronous digital system /Synchronous optical network SDH/SONET transmit frame, and use polynomial g(x)=x ⁷ +x ⁶ +1 to scramble the transmit frame;

(8) Perform bit conversion on the bytes of the synchronous digital system/synchronous optical network SDH/SONET transmission frame, or the above-mentioned (scrambled) mixed stream bytes in the bare optical fiber/cable transmission mode, and use the transmission clock to generate differential output data signals , output to the line by driving the output data signal.

The receiving direction is carried out according to the following process described in Figure 1(b):

(1) Receive the synchronous digital system/synchronous optical network SDH/SONET mixed stream when sending frames or bare optical fiber/cable transmission mode, recover the clock and data from the input differential data (or directly input the clock), and convert the data bits into byte;

(2) In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, frame delimitation is performed according to the (A ₁ , A ₂ ) byte of the synchronous digital system/synchronous optical network SDH/SONET frame, and the descrambling polynomial is used g(x)=x ⁷ +x ⁶ +1 for descrambling;

(3) In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, extract and process the segment overhead SOH and channel overhead POH of the synchronous digital system/synchronous optical network SDH/SONET frame, and detect the remote deterioration indicator RDI and alarm of the line Indicates whether an error occurs in the signal AIS, byte interleaved parity check BIP-x (x=8 or 96), and gives a corresponding error indication;

(4) When the synchronous digital system/synchronous optical network SDH/SONET transmission mode, according to the pointer indication in the control overhead, take out the payload in the virtual container/virtual tributary VC/VT;

(5) In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, if the payload in the virtual container/virtual tributary VC/VT of the sender has been scrambled, the polynomial x ⁴³ +1 is used for self-synchronous descrambling ; In the bare optical fiber/cable transmission mode, the polynomial x ⁴³ +1 is used to descramble the scrambled data bytes;

(6) Search for "special flag F" in the received byte stream, and perform byte "destuffing" processing, identify and delete PPDU format 3 and abnormal interruption in the rate-adapted filling protocol data unit PPDU Grouping, the data between two "special flags F" is used as a protocol data unit PDU for subsequent processing;

(7) When the header error control HEC field in the unified framing protocol data unit UFPDU or letter element of the sender exists, complete the error control processing of the header of the protocol data unit PDU according to ITU I.361. The correct protocol data unit PDU of the error control HEC is processed subsequently, and the protocol data unit PDU that is still incorrect after being processed by the header error control HEC is discarded;

(8) In the correct protocol data unit PDU received by the header error control HEC, identify the unified framing protocol data unit UFPDU and the cell, if the payload type PT field ≠ 111B and the length is 52/53, then determine the protocol data unit PDU is a letter element, if the load type PT=111B, then determine that the protocol data unit PDU is a unified framing protocol data unit UFPDU, and when the packet check sequence PCS of the unified framing protocol data unit UFPDU exists, it is then cycled Redundancy check CRC-32 processing;

(9) Process the filling protocol data unit PPDU, take out the load of the unified framing protocol data unit UFPDU, put it into the first-in-first-out memory of the received packet, and perform possible protocol data unit PDU format conversion on the cell, and then the protocol data The unit PDU is put into the first-in-first-out memory of the received cells;

(10) According to the standard media independent interface MII and asynchronous transfer mode universal test and operation interface UTOPIA and other interfaces to transmit protocol data unit PDU format requirements, take out the packet and cell in the received packet/cell first-in-first-out memory, complete possible After the format conversion, it is sent to network components such as user terminals, transmission equipment, and switches.

In the method for mixed transmission of variable-length data packets and fixed-length cells, the unified framing protocol data unit (UFPDU) is sequentially composed of control header, header extension, variable-length data packet and PCS field.

The above method for mixed transmission of variable-length data packets and fixed-length cells, wherein the rate adaptation is to send the unified framing protocol data unit UFPDU in order from high to low according to the priority when the cells are not sent. , when the unified framing protocol data unit UFPDU is not sent, the padding protocol data unit PPDU used for rate adaptation is sent, and the padding protocol data unit PPDU has a different format.

The above-mentioned mixed transmission method of variable-length data packets and fixed-length cells, wherein the process of transparent processing is:

(1) The sender replaces the "special flag F" that appears in the sending protocol data unit PDU with two bytes, one is "escape 8-bit binary group", the other is "special flag F" and "filling special mask code" (8-bit binary group) after "XOR" value;

(2) The sender replaces the "escaped 8-bit binary group" that appears in the sending protocol data unit PDU with two bytes, one is "escaped 8-bit binary group", and the other is "escaped 8-bit binary group" Group" and "filling special mask" (8-bit binary group) after "XOR" value;

(3) The settings of "escape 8-bit binary group" and "fill special mask" can be changed, and the default values of the two are 0x7d (hexadecimal) and 0x20 respectively, and the transparent processing transformation will replace 0x7e and 0x7d with (0x7d, 0x5e) and (0x7d, 0x5d).

In the mixed transmission method of variable-length data packets and fixed-length cells, the receiver performs byte "defilling" processing by first replacing (0x7d, 0x5e) and (0x7d, 0x5d) with 0x7e and 0x7d respectively, Then, the data between the two "special flags F" is identified as a protocol data unit PDU.

In the method for mixed transmission of variable-length data packets and fixed-length cells, the unified framing protocol data unit (UFPDU) encapsulated by variable-length packets is composed of the following fields:

(1) Unified Framing Protocol Virtual Connection Identifier/Unified Framing Protocol Network Node Identifier UFPVCI/UFPNNI field, which is used to indicate the logical virtual connection identifier or hierarchical area network node address of the Unified Framing Protocol Data Unit UFPDU . When it represents the virtual connection identifier UFPVCI of the unified framing protocol, its meaning is similar to the virtual channel identifier/virtual path identifier VPI/VCI in the ATM cell of the asynchronous transfer mode, which is allocated by the signaling protocol; when it represents the network node address , it is used to distinguish different network nodes in the unified framing protocol networking area;

(2) The payload type PT field, which is used to distinguish the unified framing protocol data unit UFPDU and the fixed-length cell in the mixed flow of the unified framing protocol data unit UFPDU and the fixed-length cell;

(3) Packet loss priority PLP field, which is used to identify the packet loss priority in the unified framing protocol data unit UFPDU. During packet transmission, if congestion occurs in the transfer/switching node, the PLP can be discarded first = 1 grouping;

(4) header error control HEC field, which adopts the same processing as the header error control HEC of the standard cell, and is used to ensure the correctness of the protocol data unit PDU header;

(5) The packet check sequence exists to identify the PCSE field, which indicates whether to use the packet check sequence PCS to perform error control on the relevant fields of the unified framing protocol data unit UFPDU;

(6) Packet priority field PPF field, which is used to identify the load packet priority of the unified framing protocol data unit UFPDU, which is convenient for the network transfer/switching node to perform different processing on the protocol data unit PDU;

(7) High layer protocol identifier ULPI field, which is used to identify information such as the type of high layer data protocol carried in the unified framing protocol data unit UFPDU;

(8) The last paragraph indicates the LSI field, which is used to identify whether the payload area of a certain unified framing protocol data unit UFPDU is the beginning or middle part of a certain high-level user protocol data unit PDU, or is a certain high-level user protocol data unit The full or last part of the PDU;

(9) The Payload field, which is used to store a complete protocol data unit PDU or a part of a protocol data unit PDU (user data packet) of a high-level user, or an operation management and maintenance OAM packet;

(10) Packet Check Sequence PCS field, which is used to perform error check protection on the header, header extension, and data load area (or only the header extension and data load area) of the unified framing protocol data unit UFPDU, The generating polynomial is g(x)=x ³² +x ²⁶ +x ²² +x ¹⁶ +x ¹² +x ¹¹ +x ¹⁰ +x ⁸ +x ⁷ +x ⁵ +x ⁴ +x ² +x+1;

It should be noted that the header error control HEC field in the unified framing protocol data unit UFPDU, the entire header extension field (packet check sequence presence identifier PCSE, packet priority field PPF, high-level protocol identifier ULPI, and the last segment indicating LSI ) and the packet check sequence PCS field can be programmed to choose whether to use.

In the mixed transmission method of variable-length data packets and fixed-length cells, the filling protocol data unit PPDU has the following five forms:

(1) Filling PDU format 1, which is used for operation, maintenance and management OAM when the unified framing protocol is connected to the network. The filling PDU includes the header and the payload area of the unified framing protocol data unit UFPDU, and the content of the payload area is related to the operation of the asynchronous transfer mode ATM The load of maintenance and management OAM is the same;

(2) fill PDU format 2, be the operation maintenance management OAM cell of asynchronous transfer mode ATM, the operation maintenance management OAM cell of this filling PDU and standard asynchronous transfer mode ATM is identical;

(3) Filling PDU format 3, consisting of three 8-bit binary groups such as "special flag F", special character 0xdd (programmable to other values), "special flag F", this format is suitable for synchronous digital system/synchronous optical High occupancy rate of network SDH/SONET or bare optical fiber/cable transmission lines;

(4) filling PDU format 4, including the header of the unified framing protocol data unit UFPDU, without header extension, payload area, packet check sequence PCS field;

(5) Filling PDU format 5, which is a standard asynchronous transfer mode ATM idle cell.

The transmission of filling PDU format 1 and format 2 depends on the transmission bandwidth of the operation, maintenance and management OAM protocol data unit. When filling PDU format 1 and format 2 are not sent, the preferred order of filling PDU sending is filling PDU format 3 and filling PDU format 4 , Filling PDU format 5.

The adaptation device that realizes the object of the present invention comprises: service side interface, grouping/asynchronous transfer mode cell Packet/ATMCell first-in-first-out memory FIFO, unified framing protocol data unit/asynchronous transfer mode cell UFPDU/ATM Cell sending processor, Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Transmit Processor, Line Side Interface, Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Receiver Processor, Unified Framing Protocol Data Unit/Asynchronous Transfer Mode Cell UFPDU/ATM Cell Receiving and Processing devices, overhead interfaces, microprocessor interfaces and other units or modules, among which the synchronous digital hierarchy/synchronous optical network SDH/SONET transmit processor and synchronous digital architecture/synchronous optical network SDH/SONET receiving processor are only used Optical network SDH/SONET transmission mode.

The functions and connections of each module are as follows:

(1) The service side interface is used to send/receive data frames and cells through the service input/output interface, realize the packet or cell transmission with the packet/cell first-in-first-out memory FIFO, and complete the service input/output interface and packet /Format conversion between the protocol data unit PDU in the cell first-in-first-out memory FIFO, this interface is connected with the service input/output interface, sending and receiving packets/cell first-in-first-out memory FIFO;

(2) Packet/ATM Cell (Packet/ATM Cell) first-in-first-out memory FIFO, including four memories such as sending/receiving packet first-in-first-out memory FIFO and sending/receiving cell first-in-first-out memory FIFO, which are used to store sending and receiving For packets and cells in the receiving direction, the four memories are connected to the service side interface, unified framing protocol data unit/cell UFPDU/ATM Cell sending or receiving processor;

(3) Unified framing protocol data unit/cell UFPDU/ATM Cell sending processor, which is used to complete the packet and cell input into the packet/cell first-in-first-out memory FIFO, and encapsulate them into unified framing protocol data unit UFPDU and Modified cells, mixed unified framing protocol data unit UFPDU and modified cells, add padding protocol data unit PPDU to realize rate adaptation, and add "special flag F" to distinguish boundaries between protocol data units PDUs. After transparent processing and scrambling of the payload to be loaded into the virtual container/virtual tributary VC/VT or bare optical fiber/cable transmission line, in the synchronous digital system/synchronous optical network SDH/SONET transmission mode, output to the synchronous Digital system/synchronous optical network SDH/SONET transmission processor, and in the bare fiber/cable transmission mode, directly output to the line side interface;

(4) Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Transmitting Processor, used to send and process Unified Framing Protocol Data Unit/Cell UFPDU/ATM Cell in Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET transmission mode The protocol data unit PDU mixed stream input by the device is loaded (mapped) into the virtual container/virtual tributary VC/VT of the synchronous digital system/synchronous optical network SDH/SONET, generating segment overhead SOH and channel overhead POH, and assembling the synchronous digital system/ Synchronize optical network SDH/SONET frame, scramble the frame and send it to the line side interface;

(5) Line-side interface, used for parallel/serial input to the synchronous digital system/synchronous optical network SDH/SONET transmission processor, or the input of the unified framing protocol data unit/cell UFPDU/ATM Cell transmission processor Exchange, generate transmission clock and differential data signal, output the data signal to the line; receive input data signal from the physical line, complete the recovery of the received clock signal and data recovery, and perform data serial/parallel conversion, according to the synchronous digital system/synchronous optical Network SDH/SONET and bare fiber/cable two different transmission methods, the converted data is transmitted to the Synchronous Digital System/Synchronous Optical Network SDH/SONET receiving processor, or unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor;

(6) Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor, search the data input by the line side interface to determine the starting position of the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET frame, and descramble the received data frame , take out the segment overhead SOH and channel overhead POH in the frame, determine the starting position of the virtual container/virtual branch VC/VT and the starting position of the first complete protocol data unit PDU in the payload area according to the pointer mechanism, and then the frame The middle data is sent to the unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor;

(7) Unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor, used for the virtual container/virtual tributary VC/VT payload area input to the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor Data, or the data input by the line-side interface in the bare fiber/cable transmission mode, undergoes descrambling, receiving delimitation, and "de-stuffing" processing, completes the header error control HEC calculation of the received packet, and identifies the unified framing protocol data unit UFPDU and cells, delete and fill the protocol data unit PPDU, complete the calculation of the packet check sequence PCS, convert the correct format of the unified framing protocol data unit UFPDU and cells, and send them to the receiving packet/cell first-in-first-out memory FIFO respectively, and pass the service The side interface converts the format and outputs it;

(8) Overhead interface, which is used to complete the setting and retrieval of OAM-related information for operation, maintenance and management. This interface is compatible with the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Transmit Processor, Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Receiver Processor 1. The unified framing protocol data unit/cell (UFPDU/ATM Cell) sending processor is connected with the unified framing protocol data unit/cell (UFPDU/ATM Cell) receiving processor;

(9) Microprocessor interface, used to realize the connection with an external microprocessor, and complete the configuration and status output of the adapter device.

It should be noted that the synchronous digital hierarchy SDH virtual container VC is functionally the same as the synchronous optical network SONET virtual tributary VT, so the description of the synchronous digital hierarchy SDH virtual container VC in the present invention is also applicable to the synchronous optical network SONET virtual tributary VT.

The above-mentioned adaptation device, wherein the unified framing protocol data unit/cell UFPDU/ATM Cell sending processor outputs to the synchronous digital system/synchronous optical network SDH/SONET sending processor or the protocol data unit PDU mixed flow of the line side interface has 4 Types, unified framing protocol data unit UFPDU, cell, padding protocol data unit PPDU and "special flag F".

The above-mentioned adaptation device, wherein the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor or the line side interface outputs to the protocol data unit PDU mixed flow of the unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor has 4 Types, unified framing protocol data unit UFPDU, cell, padding protocol data unit PPDU and "special flag F".

The present invention has the following advantages:

(1) Complete the hybrid transmission of variable-length data packets and fixed-length cells on a single virtual container/virtual tributary VC/VT or bare optical fiber/cable of synchronous digital system/synchronous optical network SDH/SONET, greatly improving transmission efficiency ;

(2) It can also complete the transmission of variable-length data packets or fixed-length cells alone on a single virtual container/virtual branch VC/VT or bare optical fiber/cable of Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET;

(3) In the connection-oriented transmission mode, the defined variable-length data packet control header is fully compatible with the standard cell header, which reduces the processing complexity in related transmission and exchange;

(4) According to the business characteristics of high-level data packets, it can be determined whether to use the packet check sequence PCS to provide error check protection, which has a wide range of applications;

(5) Provide the protocol type indication function of high-level data packets (such as IPv4, IPv6, etc.);

(6) Provide priority for the transmission of variable-length data packets, which is convenient for switching equipment to adopt differentiated services to improve the service quality QoS of real-time services;

(7) Provide data packet segmentation/reassembly functions that may be required by high-level data packets;

(8) It can provide a connectionless data transmission function similar to the Internet Protocol IP network for high-level data packets.

Description of drawings:

Fig. 1 is a functional block diagram of the mixed transmission method of variable-length data packets and fixed-length cells proposed by the present invention.

Fig. 2 is a format diagram of the unified framing protocol data unit proposed by the present invention.

Fig. 3 is a diagram of the ATM cell format of the modified asynchronous transfer mode proposed by the present invention.

Fig. 4 is a schematic diagram of mixed transmission of advanced data link control HDLC frame flag, variable-length unified framing protocol data unit and fixed-length cells.

Fig. 5 is a schematic diagram of mixed transmission of variable-length unified framing protocol data unit and fixed-length cell stream mapped to a single virtual container VC of synchronous digital hierarchy SDH.

Fig. 6 is an adaptation processing device for mixed transmission of variable-length unified framing protocol data units and fixed-length cells.

FIG. 7 is a format diagram of an Ethernet physical layer frame.

FIG. 8 is a format diagram of an Ethernet media access control MAC frame.

FIG. 9 is a format diagram of a unified framing protocol data unit (UFPDU) generated when transmitting an Ethernet medium access control MAC frame.

Fig. 10 is a diagram of an application example of the present invention.

Detailed ways:

The implementation method and device of the present invention will be described in detail below in conjunction with the accompanying drawings.

As shown in Figure 2, the unified framing protocol data unit UFPDU proposed by the present invention includes the unified framing protocol virtual connection identifier/unified framing protocol network node identifier UFPVCI/UFPNNI field, load type PT field, packet loss Priority PLP field, header error control HEC field, packet check sequence presence identifier PCSE field, packet priority field PPF field, high-level protocol identifier ULPI field, last segment indication LSI, payload field, packet check sequence PCS field, etc. , the meanings of each field in the protocol data unit are as follows:

(1) Unified Framing Protocol Virtual Connection Identifier/Unified Framing Protocol Network Node Identifier UFPVCI/UFPNNI (28 bits), which is used to identify the logical identifier or hierarchical area network node related to the Unified Framing Protocol Data Unit UFPDU address.

The UFPVCI/UFPNNI field has the following two forms: the first form is that it represents the virtual connection identifier UFPVCI of the unified framing protocol, and its meaning is similar to the virtual channel identifier/virtual channel identifier VPI/VCI in the cell, where the virtual channel The VPI part of the identifier occupies 8/12 bits, corresponding to the user network interface/network node interface UNI/NNI respectively, and the VCI part of the virtual path identifier occupies 16 bits, which is allocated by the signaling protocol; the second form is that it represents unified framing The protocol network node identifier UFPNNI, that is, the network node address, is used to distinguish different network nodes in the UFP networking area. The unified framing protocol network node identifier UFPNNI has a total of 28 bits, the first 14 bits indicate the sink node in the unified framing protocol UFP domain of the packet, and the last 14 bits indicate the source node in the unified framing protocol UFP domain of the packet. The user endpoint address ranges (such as Internet Protocol IP addresses) included in different UFP domain nodes are specified by the network management protocol. Since this method is a connectionless method, it cannot guarantee that the packets arrive in sequence; if it is necessary to ensure that the packets arrive in sequence, the high-level protocol can add a sequence number in the payload area of the protocol data unit.

(2) Payload type PT (3 bits), which identifies the payload type of the UFPDU. When the unified framing protocol data unit UFPDU and the cell are mixed, the load type PT=111B (binary) indicates that a certain protocol data unit is a unified framing protocol data unit UFPDU, and PT≠111B indicates that a certain protocol data unit is Cell.

(3) Packet loss priority PLP (1 bit): Indicates the packet loss priority of the unified framing protocol data unit UFPDU. The function and usage of PLP are the same as the cell loss priority CLP in the cell. During the UFPDU transmission process, if congestion occurs in the transfer/switching node, the packets with packet loss priority PLP=1 can be discarded first.

(4) Packet Check Sequence Existence Flag PCSE (1 bit): flag indicating whether the unified framing protocol data unit UFPDU uses the Packet Check Sequence PCS. PCSE=1/0 respectively indicates the presence/absence of the packet check sequence PCS field.

(5) Packet priority field PPF (3 bits): indicates the packet priority of the unified framing protocol data unit UFPDU. PPF=000~111B indicates the priority of the load, and 111 indicates the highest priority.

(6) High-level protocol identifier ULPI (3 bits): identifies information such as the high-level data protocol type of the Payload of the unified framing protocol data unit UFPDU. The high-level protocol identifier ULPI=0x04 indicates that the UFPDU payload is an IPv4 packet, ULPI=0x06 indicates that the UFPDU payload is an IPv6 packet, and ULPI=0x07 indicates that the UFPDU payload is a point Point-to-Point Protocol PPP packet. Other ULPI values are temporarily reserved.

(7) The last section indicates LSI (1 bit): the last section indicates that LSI=1 identifies that the payload area of a certain unified framing protocol data unit UFPDU is the complete part or the last part of a certain high-level user protocol data unit, and LSI=0 Identify the payload area of a unified framing protocol data unit (UFPDU) as the beginning or middle part of a certain high-level user protocol data unit.

(8) Header error control HEC (8 bits): The header error control adopts the same processing as the header error control HEC in the standard cell, that is, the generator polynomial g(x)=x ⁸ +x ² +x+1 pair Calculate the remainder of the multiplication result of the header 4-byte information polynomial and ^x8 , and put the remainder into this field after adding 01010101B for processing.

(9) Payload Payload: the payload area stores a complete protocol data unit or a part of a protocol data unit (user data packet) of a high-level user, or an OAM packet for operation, management and maintenance.

(10) Packet Check Sequence PCS (32 bits): Used to perform error check protection on the header, header extension, and data payload area (or header extension and data payload area) of the unified framing protocol data unit UFPDU, The generator polynomial is g(x)=x ³² +x ²⁶ +x ²² +x ¹⁶ +x ¹² +x ¹¹ +x ¹⁰ +x ⁸ +x ⁷ +x ⁵ +x ⁴ +x ² +x+1.

It should be noted that the fields in the dashed box in Figure 2 are optional, that is, the header error control HEC in the unified framing protocol data unit UFPDU, the entire header extension field (packet check sequence presence flag PCSE, packet priority Level field PPF, high layer protocol identifier ULPI, last segment indication LSI), packet check sequence PCS field can be programmed to choose whether to use.

As shown in Fig. 3, the modified asynchronous transfer mode ATM cell proposed by the present invention has a load of fixed-length packets. The meaning of each field in the protocol data unit is the same as that of the corresponding field in the standard cell, the difference is that the header error control HEC field (in the dashed box) in the protocol data unit is optional, that is, it is determined by the network management does it exist.

As shown in Fig. 4, the protocol data unit mixed flow of the present invention is made up of " special mark F ", unified framing protocol data unit UFPDU, cell and filling protocol data unit PPDU, wherein the effect of filling protocol data unit PPDU is rate adaptation match. The length of "special flag F" is one byte (octet binary group), which can distinguish the boundary between two adjacent protocol data units in the mixed stream of protocol data units. These protocol data units include unified framing protocol data unit UFPDU , cell and filling protocol data unit PPDU, two adjacent protocol data units can belong to the same type (such as a cell and a cell), and can also belong to different types (such as a unified framing protocol data unit UFPDU and a cell). When sending the unified framing protocol data unit UFPDU, cell and padding protocol data unit PPDU, the sending order of the bytes starts from byte number 1, and the sending order of the bits in the byte starts from the most significant bit of the byte (bit 7) to the lowest bit (bit 1).

As shown in Figure 5, the unified framing protocol data unit UFPDU and the cell of the present invention are sequentially loaded (or mapped) into the virtual container VC of the Synchronous Digital Hierarchy SDH according to policies such as service priority, and the pointer adjustment is performed by the segment overhead SOH The H1 and H2 bytes are given. Since the beginning of the cell and the unified framing protocol data unit UFPDU is changed in the virtual container VC payload area, it should be noted that the last part of a virtual container VC payload area may only be loaded with a protocol data unit (cell or unified group frame protocol data unit UFPDU), and the rest of the same protocol data unit is loaded into the beginning part of the virtual container VC load area of the next Synchronous Digital Hierarchy SDH frame.

As shown in Figure 6, the adaptation device of the present invention includes: service side interface, packet/asynchronous transfer mode cell Packet/ATM Cell FIFO, unified framing protocol data unit/cell UFPDU/ATM Cell sending process Device, Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Transmit Processor, Line Side Interface, Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Receiver Processor, Unified Framing Protocol Data Unit/Cell UFPDU/ATMCell Receiver Processor, Overhead interface, microprocessor interface and other units or modules, but the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Transmit Processor and Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET Receive Processor are only used for Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET transmission mode, in which:

The service side interface, the completed functions include: (1) generate and identify the control signals required by the service input/output interface, and send/receive data on the service input/output interface; (2) realize and send the cell first-in first-out memory FIFO, sending packet FIFO, receiving packet FIFO, receiving cell FIFO, packet or cell transmission among four memories; (3) realize service input/output interface and the above four Protocol data unit PDU format conversion between memories.

When transmitting Ethernet services, the protocol data unit transmitted in the service input/output interface is the Ethernet physical frame shown in Figure 7, and the service side interface converts the Ethernet physical frame into the Ethernet media access frame shown in Figure 8. Control the MAC frame and output it to the first-in-first-out memory FIFO for sending packets. The Ethernet media access control MAC frame is an Ethernet physical frame except the two fields of the preamble and the frame start delimiter, and the remaining fields are transmitted as the payload of the unified framing protocol data unit UFPDU. The transmission interface types supported by the service input/output interface include: (1) Universal Test and Operation Interface UTOPIA for Asynchronous Transfer Mode, (2) PoS Interface for Packet Transmission on Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET, (3) Media Independent Interface MII interface, (4) synchronous digital system/synchronous optical network SDH/SONET interface for transmitting cells, (5) quasi-synchronous digital system PDH interface for transmitting cells or data packets, (6) cell transmission defined by ATM Forum interface.

Packet/Cell Packet/ATM Cell FIFO, including sending cell FIFO, sending packet FIFO, receiving packet FIFO, receiving cell FIFO The memory is used to store variable-length packets and cells in the sending and receiving directions.

Unified framing protocol data unit/cell UFPDU/ATM Cell sending processor, complete the following functions:

(1) Generate and send a unified framing protocol data unit/cell

Perform possible format conversion on the cell received from the ATM Cell first-in-first-out memory FIFO of the sending cell, that is, decide whether to use the header error control HEC field according to the setting of the hybrid transmission system.

Encapsulating the variable-length packets received from the FIFO of the sending packet Packet into a unified framing protocol data unit UFPDU. When the variable-length packet is encapsulated into a UFPDU, the hybrid transmission device THE at the network source adds a header, header extension, and packet check sequence to the variable-length packet.

Set the unified framing protocol virtual connection identifier/unified framing protocol network node identifier UFPVCI/UFPNNI field in the header, make the payload type PT=111B, and set the packet loss priority PLP=0/1 according to the importance of the packet. The header error control HEC field is optional, but if the packet check sequence PCS is not selected for use (at this time, the packet check sequence exists and the flag PCSE=0), then the header error control HEC field must be used, and its generator polynomial is g( x)=x ⁸ +x ² +x+1, the calculation method of the header error control HEC at the sender is the same as the calculation method of the cell HEC.

Need to carry out the data of packet check sequence PCS protection for World Wide Web WWW business etc., set packet check sequence existence sign PCSE=1; For the data that does not need packet check sequence PCS error protection such as IP voice VoIP, set packet check sequence existence sign PCSE=0. Set the packet priority field PPF=000~111B according to the quality of service QoS characteristics of the business. According to the protocol of the high-level data load, set a reasonable high-level protocol identifier ULPI value. When the payload is an IPv4 packet, set ULPI=0x04, when the payload is an IPv6 packet, set ULPI=0x06, and when the payload is a PPP packet, set ULPI=0x07. The use of other values of ULPI can be defined at the time of implementation.

At the source network component, if the length of the protocol data unit to be sent is greater than the maximum transmission unit length MTU, the information to be sent needs to be divided according to the length of [MTU minus PDU control overhead length] to form M data blocks (1, 2 , 3, ---, M, M is a positive integer). When the data blocks are assembled into a unified framing protocol data unit UFPDU, for the unified framing protocol data unit UFPDU formed by loading the data block (1, 2, ---, M-1) into the payload, set its last segment to indicate LSI =0, and for the unified framing protocol data unit UFPDU formed by the last data block M, set its last segment indication LSI=1.

The load area is loaded with a complete high-level protocol data unit PDU or a part thereof, or an OAM packet for operation, maintenance and management.

The polynomial used in the PCS calculation of the packet ^check sequence is g(x)=x ³² +x ²⁶ +x ²² +x ¹⁶ +x ¹² +x ¹¹ +x ¹⁰ +x 8 +x ⁷ +x ⁵ +x ⁴ +x ² +x+1.

When the packet check sequence existence flag PCSE=1, the information field protected by the packet check sequence PCS depends on whether the header error control HEC field exists. When the header error control HEC field exists, the information field protected by the packet check sequence PCS is the header extension and payload field of the unified framing protocol data unit UFPDU; when the header error control HEC field does not exist, the packet check sequence The information fields protected by the PCS are the header, header extension and payload fields of the unified framing protocol data unit UFPDU. When the packet check sequence existence flag PCSE=0, the packet check sequence PCS field does not exist.

The typical calculation method of the sender's packet check sequence PCS is: set the initial value of the remainder register to all "1" (32 bits), assume that the information polynomial of the information field to be protected is m(x), and calculate m(x) x ³² ÷ The remainder of g(x) (modulo '2' division), after the above remainder is XORed with 0xFFFFFFFF, it is put into the PCS field of the packet check sequence, the highest bit is placed in bit 7 of byte (N-3), and the lowest bit Put in bit 0 of byte N.

When transmitting Ethernet medium access control MAC frames, the unified framing protocol data unit/cell UFPDU/ATMCell sending processor takes the Ethernet medium access control MAC frame as the payload, and the unified framing protocol data unit generated according to the above processing UFPDU is shown in Figure 9.

(2) Rate adaptation

The function of rate adaptation is to add filling protocol data unit PPDU to the mixed flow of "special flag F", unified framing protocol data unit UFPDU, and cell protocol data unit, so as to ensure that it is sent to the synchronous digital system/synchronous optical network SDH The sum of the rate of the above-mentioned protocol data unit and the padding protocol data unit PPDU of the SONET processor or the line side interface is equal to the net rate of the virtual container VC of the synchronous digital hierarchy SDH, or the transmission rate of the bare fiber/cable physical line, for example, for synchronous Transmission module STM-1, the rate is 149.76Mbps. The principle of rate adaptation is: to send cells first. When there is no cell to send, the unified framing protocol data unit UFPDU with priority from high to low is sent sequentially. If there are neither cells nor UFPDUs waiting to be sent, a padding protocol data unit PPDU for rate adaptation will be sent, which has the following form:

1) Filling PDU format 1 is used for operation, maintenance and management OAM when the unified framing protocol is connected to the network. The filling PDU includes the unified framing protocol data unit UFPDU header and payload area in Figure 2, and is identified by a specific unified framing protocol virtual connection Character/Unified Framing Protocol Network Node Identifier UFPVCI/UFPNNI identifies the unified framing protocol data unit UFPDU of the virtual path level F4 and virtual path level F5, the header error control HEC is a must, the content of the payload area and the asynchronous transfer mode The load of ATM operation maintenance management OAM is the same;

2) filling PDU format 2 is the operation maintenance management OAM cell of the asynchronous transfer mode ATM of Fig. 3 format, and this filling PDU is identical with the operation maintenance management OAM cell of standard asynchronous transfer mode ATM;

3) Filling PDU format 3 consists of 3 8-bit binary groups such as "special flag F", special character 0xdd (programmable to other values), "special flag F", etc. This format is suitable for synchronous digital system/synchronous optical network SDH /SONET or bare optical fiber/cable transmission line occupancy is high;

4) The padding PDU format 4 includes the header of the unified framing protocol data unit UFPDU shown in Fig. 2, and the header error control HEC is a necessary item at this time. The 5 bytes of the header of the unified framing protocol data unit UFPDU are (0x0, 0x0, 0x0, 0x1, the effective value of the header error control HEC), and there is no header extension, payload area, and packet check sequence PCS field;

5) filling PDU format 5 is an ATM idle cell in asynchronous transfer mode, and its cell head 5 bytes are (0x0, 0x0, 0x0, 0x1, the effective value of header error control HEC), and the payload field places 48 bytes of " 01101010".

The transmission of filling PDU format 1 and format 2 depends on the transmission bandwidth of OAM protocol data unit for operation, maintenance and management. When filling PDU format 1 and format 2 are not sent, the preferred sending order of filling PDU is filling PDU format 3, filling PDU format 4, Fill PDU Format 5.

(3) Transparency processing

Transparency processing is completed The processing method when "special flag F" appears in the sent PDU, where "special flag F" refers to the flag used for boundary positioning between different PDUs, using 0x7e, and can also be programmed to other values.

The sender replaces the "special flag F" that appears in the sending protocol data unit PDU with two bytes, one is "escape 8-bit binary group", the other is "special flag F" and "filling special mask" ( 8-bit binary group) value after "exclusive OR". The above processing is also performed on the escaped 8-bit binary group appearing in the sending PDU. Both the escape 8-bit binary group and the padding special mask can be changed by software, and the default values are 0x7d and 0x20 respectively. As an example, the transparent processing transformation is as follows:

1) Replace 0x7e with 0x7d, 0x5e

2) Replace 0x7d with 0x7d, 0x5d

(4) Scrambling

Unified framing protocol data unit/cell UFPDU/ATM Cell sending processor can choose (programmable) whether to scramble the mixed flow of "special flag F", unified framing protocol data unit UFPDU, cell and padding protocol data unit PPDU , the scrambling uses a self-synchronizing scrambler whose polynomial is x ⁴³ +1. Before the scrambling calculation starts, the initial value of the scrambling code is set to all "1".

Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET transmit processor, complete the following functions:

(1) Unified framing protocol data unit/cell UFPDU/ATM Cell mapping

The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET sending processor sends the unified framing protocol data unit/cell UFPDU/ATM Cell input "special flag F", unified framing protocol data unit UFPDU, cell and padding The protocol data unit PPDU mixed flow is loaded into the virtual container VC of the synchronous digital hierarchy SDH according to the method shown in Fig. 5 . It should be noted that this kind of mapping is generally carried out in the high-order virtual container VC, and can also be carried out in the low-order virtual container VC according to the configuration, but the multiplexing efficiency in the high-order virtual container VC is high, which can better reflect the advantages of the present invention. For example, when using virtual container VC-12 mapping, a synchronous transport module STM-1 only includes 63 virtual containers VC-12, and its maximum transmission efficiency is 63*2.048/149.76=86%. When virtual container VC-4 is used for mapping, one synchronous transfer module STM-1 includes one virtual container VC-4, and its maximum transmission efficiency is 149.76/149.76=100%.

According to the principle of the management unit pointer AU-PTR, the (H ₁ , H ₂ ) bytes in the management unit pointer AU-PTR can indicate the starting position of the virtual container VC, and H ₄ in the channel overhead POH is used to indicate the first complete The head of the protocol data unit PDU is at the position of the virtual container VC of the SDH frame of the current synchronous digital system.

(2) Generation and processing of overhead bytes

The frame delimiting bytes (A ₁ , A ₂ ) of the Synchronous Digital Hierarchy SDH frame are generated. Programmable selection of inserted line data communication channels (D ₁ -D ₁₂ ).

All bit streams after scrambling of the previous synchronous digital system SDH frame are used to calculate byte interleaving check BIP, BIP-8 adopts even check, and the result is put into B ₁ byte. Perform byte interleaving check BIP-96 even parity calculation on all bit streams of the previous synchronous digital system SDH frame except the first to third lines of the section overhead SOH, and put the result into byte B ₂ . Calculate BIP-8 for the SDH payload envelope SPE of the previous synchronous digital system SDH frame, BIP-8 uses even parity, and the result is put into B ₃ bytes.

Monitor the transmission performance of the channel according to relevant specifications, and transmit the monitoring results to the other end with _G1 bytes. Insert automatic protection switching APS channel bytes (K ₁ , K ₂ ) according to relevant specifications.

(3) Scrambling

The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET transmit processor can use a frame synchronizer to scramble the transmission frame stream. The polynomial used is g(x)=x ⁷ +x ⁶ +1, and the Synchronous Digital Hierarchy SDH frame control byte (A ₁ , A ₂ ), J ₀ and Z ₀ are not scrambled.

Line side interface

In the sending direction, the line-side interface transmits data from the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET sending processor or unified framing protocol data unit/signal according to the Synchronous Digital Hierarchy/Synchronous Optical The UFPDU/ATM Cell transmits the byte data received by the processor, completes the parallel/serial conversion, and sends it to the line in a differential manner (TXD ⁺ , TXD ^- ). The data transmission clock should meet the G.707 and Bellcore GR-253-CORE specifications, and the accuracy for 155.52MHz/622.08MHz is ±20ppm.

In the receiving direction, the line side interface recovers the clock from the received differential data (RXD ⁺ , RXD ^- ) or directly inputs the received clock reference, and recovers the data from (RXD ⁺ , RXD ^- ) to complete the serial/parallel conversion, Delivered to the Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor or Unified Framing Protocol Data Unit/Cell UFPDU/ATM Cell receiving processor. Whether the loss of detection signal LOS occurs, and if so, an indication is given through the overhead interface.

Synchronous digital system/synchronous optical network SDH/SONET receiving processor, complete the following functions:

(1) Receive segment processing

The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor can take out the segment data communication channels (D ₁ ~ D ₄ ) in the segment overhead SOH, and complete the SDH frame definition of the Synchronous Digital Hierarchy according to the (A ₁ , A ₂ ) bytes. boundary. In 4 consecutive frames, if there is a delimitation error, the out-of-frame signal LOF can be given.

The synchronous digital system/synchronous optical network SDH/SONET receiving processor descrambles the received stream, and whether to use descrambling can be programmed. The descrambling polynomial is g(x)=x ⁷ +x ⁶ +1, and the synchronous digital system SDH frame control bytes (A ₁ , A ₂ ), J ₀ , and Z ₀ do not participate in descrambling.

(2) Receive overhead processing

The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor can detect whether the remote line deterioration indication RDI and alarm indication signal AIS occur, and give an indication if they occur. The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor can take out the line data channel (D ₄ ~ D ₁₂ ) and output it through the overhead interface. According to the BIP principle of byte interleaved parity check, BIP-8 errors and BIP-96 errors can be detected, and corresponding error indications are given through the overhead interface.

(3) Receive pointer processing

The Synchronous Digital Hierarchy/Synchronous Optical Network SDH/SONET receiving processor realizes the correct interpretation of the pointer, takes out the payload in the virtual container VC, and hands it to the unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor for processing. If an invalid pointer is generated, a LOP error indicating that the corresponding pointer is missing is given through the overhead interface.

Unified framing protocol data unit / cell UFPDU / ATM Cell receiving processor, complete the following functions:

(1) Descrambling

Unified framing protocol data unit/cell UFPDU/ATM Cell receiving processor receives data mixed stream from synchronous digital system/synchronous optical network SDH/SONET receiving processor or line side interface in byte mode, and can be programmed to choose whether to input Mixed flow descrambling, the mixed flow includes "special flag F", unified framing protocol data unit UFPDU, cell and padding protocol data unit PPDU. Descrambling uses a self-synchronizing descrambler whose polynomial is x ⁴³ +1. Before the descrambling calculation starts, the initial value of the scrambling code is set to all "1".

(2) Receiving delimitation and "de-filling" processing

Search for "special flag F" in the received (after descrambling) data byte stream, perform byte "destuffing" processing (Destuffing), delete rate-adapted filling PDU (filling PDU format 3) and abnormal interrupt packet, The data between the two "special flags F" after the above processing is used as a PDU to carry out unified framing protocol data unit and cell identification. Abnormal interrupt grouping means that the number of bytes between two "special flags F" is less than 5.

The "de-stuffing" process completes the opposite process of sending, that is, the following two special 8-bit binary groups are transformed into an 8-bit binary group: 0x7d, 0x5e are replaced by 0x7e, 0x7d, 0x5d are replaced by 0x7d.

(3) Identify unified framing protocol data units and cells

When the header error control HEC field in the unified framing protocol data unit UFPDU or letter element of the sender exists, perform cyclic redundancy check on the first 4 bytes according to g(x)=x ⁸ +x ² +x+1 Check the CRC-8 calculation, add 01010101 to the result, and compare it with the received 5th byte. If it is correct, treat the protocol data unit PDU as the correct PDU for subsequent processing; otherwise, correct a single byte in the first 4 bytes. Bit error. If a multi-bit error occurs, the protocol data unit PDU is discarded.

In the received protocol data unit PDU, if the payload type PT field≠111B and the length is 52/53 (the header error control HEC field does not exist/exists), then the protocol data unit PDU is determined to be a cell. Discard the protocol data unit PDU that satisfies the payload type PT field ≠ 111B and the length ≠ 52/53.

In the received protocol data unit PDU, if the payload type PT=111B, it is determined that the protocol data unit PDU is a unified framing protocol data unit UFPDU; if the payload type PT=111B and the packet check sequence presence flag PCSE=1, then The packet check sequence PCS field exists, and the protocol data unit PDU needs to be processed by cyclic redundancy check CRC-32.

(4) Receive packet check sequence PCS calculation

The typical method for the receiver to calculate the cyclic redundancy check CRC-32 is: set the initial value of the remainder register to be all "1", and set the polynomial of the information field of the field to be protected to be m(x)', then first use serial or parallel Calculate the remainder of m(x)′·x ³² ÷g(x) by look-up table method. Exclusively OR (modulo 2 addition) the obtained remainder result with 0xFFFFFFFF, and compare the obtained result with the packet check sequence PCS in the received frame to determine whether there is an error in the protocol data unit PDU. When there is an error, correct the error that can be corrected, otherwise discard the protocol data unit PDU.

(5) Receive protocol data unit PDU storage

After determining that a protocol data unit PDU is a unified framing protocol data unit UFPDU or cell, first perform a possible format conversion of the protocol data unit PDU, and then put it into the receiving packet/cell Rx Packet/ATM Cell first-in-first-out Memory FIFOs.

The overhead interface is used for setting and taking out the operation, maintenance and management information related to the unified framing protocol data unit UFPDU of OAM and ATM cell in asynchronous transfer mode. In the synchronous digital system/synchronous optical network SDH/SONET transmission mode, the setting of optional control bytes in the segment overhead SOH and channel overhead POH in the sending direction is also completed, and the control bytes in the segment overhead SOH and channel overhead POH in the receiving direction are realized. take out.

The microprocessor interface mainly implements the interface with the external microprocessor, including the working mode setting and testing of the adapter device, the status register, the state output of the adapter device, and related control logic.

As shown in Figure 10, the present invention can be used for point-to-point transmission and point-to-multipoint or network transmission. In Figure 10(a), the hybrid transmission equipment HTE receives variable-length packets (such as Ethernet frames) and fixed-length cells from network components such as switches, routers, servers, and network terminals through standard network interfaces NI. Including media independent interface MII, asynchronous transfer mode general test and operation interface UTOPIA. The hybrid transmission equipment HTE encapsulates the received variable-length packets and fixed-length cells into protocol data units (PDUs) according to the given format of the present invention, and transfers the protocol data units (PDUs) of the two forms to the synchronous digital system/synchronous optical network SDH/ Mixed transmission on the same virtual container/virtual tributary VC/VT or bare fiber/cable of SONET. The mixed transmission equipment THE on the receiving side completes the identification and separation of the two received PDUs, and then decapsulates the two PDUs to complete the format conversion of the PDUs, and through the network interface, the variable-length data packets and The fixed-length cells are submitted to network components such as switches, or transmitted to the sink network component NE in the form submitted by the source network component NE. In Figure 10(b), the variable-length data packet/fixed-length cell transmission process in the source-sink network element NE is basically the same as that in Figure 10(a), the difference is that the network nodes (mixed transmission The equipment HTE/switch SW) has a switching function. In Fig. 10(b), it is assumed that a certain network has 6 network nodes, and the numbers are N1-N6 respectively. The source network component NE converts the format of the received variable-length data packet/fixed-length cell, and transmits it to the N1 node. The hybrid transmission equipment HTE of the N1 node completes the identification and separation of the two received PDUs, and then transmits the variable-length data packets and fixed-length cells to the switch through the standard interface to complete the exchange. Carry out standard virtual channel/virtual channel VP/VC switching on the cells, and send the cells to port 2 or port 3 of N1 respectively. There are two forms for the exchange of variable-length data packets, one is the unified framing protocol virtual connection identifier/unified framing protocol network node identifier UFPVCI/UFPNNI uses the unified framing protocol virtual connection identifier UFPVCI, at this time N1 The switch SW of the node completes the corresponding VP/VC exchange, but the basic unit of exchange is the variable-length protocol data unit PDU. The other is that UFPVCI/UFPNNI adopts the unified framing protocol network node identifier UFPNNI. At this time, the switch SW of the N1 node needs to determine the output of the protocol data unit PDU to port 2 or port 3 of N1 according to the routing algorithm. The hybrid transport equipment THE in N1 converts the format of the variable-length data packets/fixed-length cells waiting to be sent in a certain port (1, 2, 3) to form a unified framing protocol data unit UFPDU or a modified cell, The two protocol data unit PDUs are sent out through synchronous digital hierarchy/synchronous optical network SDH/SONET or bare optical fiber/cable transmission lines. The hybrid transmission equipment HTE in N2 completes the identification and separation of the unified framing protocol data unit UFPDU or the modified cell PDUs received from the N1 node, and then sends the variable-length data packets and cells to the switch SW through the standard interface Make an exchange. Other subsequent processing of the N2 node is the same as that of the N1 node. The processing of other nodes in the network is also the same as that of N1 node. The hybrid transmission equipment HTE in the sink endpoint completes the identification and separation of the unified framing protocol data unit UFPDU or the modified cell received from the N6 node, and then passes the standard interface (such as the asynchronous transfer mode general test and operation interface UTOPIA) delivers the variable-length data packets and cells to the network element NE for subsequent processing.

Claims (8)

1. an elongated packet mixes the method that transmits with fixed length cell, comprises the transmission processing that sends and receive both direction, wherein:

Sending direction is undertaken by following process:

(1) Media Independent Interface (MII), asynchronous transfer mode universal test and the operation-interface interfaces such as (UTOPIA) of use standard, receive elongated Frame and fixed length cell from network componentses such as user terminal, transmission equipment and switches, with the payload segment in the elongated Frame, it is elongated packet, deposit in and send grouping push-up storage (FIFO), and cell is directly put into transmission cell push-up storage (FIFO);

(2) the elongated packet that will send in the grouping push-up storage (FIFO) is taken out, and adds control header and extension header and packet checks sequence (PCS), is packaged into unified framing protocol Data Unit (UFPDU); The fixed length cell that will send simultaneously in the cell push-up storage (FIFO) takes out and is transformed into the cell format of modification, and header error control (HEC) field in the cell format of this modification can be selected to use;

(3) between unified framing protocol Data Unit (UFPDU) and cell, add " distinctive mark (F) " that distinguishes both borders, with border between difference different agreement data cell (PDU), and, will unify framing protocol Data Unit (UFPDU) and the cell revised mixes according to service quality (QoS) characteristic of customer service;

(4) in the mixed flow of " distinctive mark (F) " and unified framing protocol Data Unit (UFPDU) and cell composition, add filling protocol Data Unit (PPDU), guarantee that the speed sum of this (being F, UFPDU, ATM cell, PPDU) equals the net rate of the virtual container of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET)/empty branch road (VC/VT) or bare fiber/cable line, to realize rate adapted;

(5) unified framing protocol Data Unit (UFPDU), cell and filling protocol Data Unit (PPDU) being carried out the transparency handles, promptly in the unified framing protocol Data Unit (UFPDU), cell and the filling protocol Data Unit three kinds of protocol Data Units (PDU) such as (PPDU) that send, " distinctive mark (F) " of appearance handles;

(6) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, mixed flow with " distinctive mark (F) ", unified framing protocol Data Unit (UFPDU), cell, filling protocol Data Unit (PPDU) composition, pack into or be mapped to virtual container/empty branch road (VC/VT) of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET), and to the net load in virtual container/empty branch road (VC/VT), the employing multinomial is x ⁴³+ 1 self-synchronous scrambler carries out selectable scrambling; When bare fiber/cable load mode, only above-mentioned mixed flow being adopted multinomial is x ⁴³+ 1 self-synchronous scrambler carries out selectable scrambling;

(7) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, the section overhead (SOH) and the path overhead (POH) that net load after the scrambling are added SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) frame, form SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) transmit frame, and this transmit frame is adopted multinomial g (x)=x ⁷+ x ⁶+ 1 carries out scrambling;

(8) to SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) transmit frame, or the byte of above-mentioned (after the scrambling) mixed flow during bare fiber/cable load mode is carried out the bit conversion, and use tranmitting data register to produce the difference outputting data signals, by driving, output on the circuit this outputting data signals;

Receive direction is undertaken by following process:

Mixed flow when (1) receiving SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) transmit frame or bare fiber/cable load mode, recovered clock and data from the differential data of input (or directly input clock) are transformed to byte with data bit;

(2) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, according to (the A of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) frame ₁, A ₂) byte is carried out the frame demarcation, and employing descrambling multinomial g (x)=x ⁷+ x ⁶+ 1 carries out descrambling;

(3) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, take out and handle the section overhead (SOH) and the path overhead (POH) of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) frame, the detection line far-end worsens indication (RDI), alarm indication signal (AIS), whether byte-interleaved parity check BIP-x (x=8 or 96) mistake takes place, and provides corresponding wrong indication;

(4) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode,, take out the net load in virtual container/empty branch road (VC/VT) according to the pointer indication in the control expense;

(5) when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, if multinomial x is then adopted in the net load scrambling in transmit leg virtual container/empty branch road (VC/VT) ⁴³+ 1 carries out the motor synchronizing descrambling; When bare fiber/cable load mode, the data byte of scrambling is adopted multinomial x ⁴³+ 1 carries out descrambling;

(6) search " distinctive mark (F) " in the byte stream that receives, and carry out byte and " go to fill " (Destuffing) processing, PPDU form 3 in the filling protocol Data Unit (PPDU) of identification and deletion rate adapted and aborted grouping are carried out subsequent treatment with the data between two " distinctive mark (F) " as a protocol Data Unit (PDU);

(7) unify header error control (HEC) in framing protocol Data Unit (UFPDU) or the cell when field exists when transmit leg, I.361 finish the error control of protocol Data Unit (PDU) header handles according to the ITU of International Telecommunication Association, the protocol Data Unit (PDU) correct to header error control (HEC) carries out subsequent treatment, still incorrect protocol Data Unit (PDU) after abandoning header error control (HEC) and handling;

(8) in the correct protocol Data Unit (PDU) of the header error control (HEC) that receives, unified framing protocol Data Unit (UFPDU) of identification and cell, if load type (PT) field ≠ 111B and length are 52/53, judge that then this protocol Data Unit (PDU) is a cell, if load type (PT)=111B, judge that then this protocol Data Unit (PDU) is unified framing protocol Data Unit (UFPDU), when the packet checks sequence (PCS) of unified framing protocol Data Unit (UFPDU) when existing, again it is carried out cyclic redundancy check (CRC) (CRC-32) and handle;

(9) handle filling protocol Data Unit (PPDU), to unify the load of framing protocol Data Unit (UFPDU) takes out, put into and receive grouping push-up storage (FIFO), and cell carried out possible protocol Data Unit (PDU) format conversion, this protocol Data Unit (PDU) is put into received cell push-up storage (FIFO) again;

(10) according to the call format of transport protocol data unit (PDU) on the Media Independent Interface (MII) of standard and asynchronous transfer mode universal test and the operation-interface interfaces such as (UTOPIA), take out to receive grouping and cell in the packet/cell push-up storage (FIFO), send to network componentses such as user terminal, transmission equipment and switch after finishing possible format conversion.

2. method according to claim 1 is characterized in that unifying framing protocol Data Unit (UFPDU) and is made up of control header, extension header, elongated packet and packet checks sequence (PCS) field successively.

3. method according to claim 1, it is characterized in that rate adapted divides three kinds of situations to send, promptly one is directly to send cell, the 2nd, when not sending cell, according to priority send unified framing protocol Data Unit (UFPDU) from high to low successively, the 3rd, if in the unit that neither posts a letter, when also not sending out framing protocol Data Unit (UFPDU) unified, send the filling protocol Data Unit (PPDU) of different-format.

4. method according to claim 1 is characterized in that being made up of following field the unified framing protocol Data Unit (UFPDU) that variable-length packets is packaged into:

(1) unify framing agreement virtual connections identifier/unification framing protocol network node identifier (UFPVCI/UFPNNI) field, this field is used to represent the logic virtual connections sign or the stepped zone network node address of unified framing protocol Data Unit (UFPDU); When the unified framing agreement virtual connections identifier of expression (UFPVCI), its implication is similar to the Virtual Path Identifier/virtual path identifiers (VPI/VCI) in asynchronous transfer mode (ATM) cell, is distributed by signaling protocol; When expression network node address, be used to distinguish the heterogeneous networks node in the unified framing agreement networking zone;

(2) load type (PT) field, this field is used for distinguishing the unified framing protocol Data Unit (UFPDU) and the fixed length cell of unified framing protocol Data Unit (UFPDU) and fixed length cell mixed flow;

(3) packet loss priority (PLP) field, this field is used for identifying the packet loss priority of unified framing protocol Data Unit (UFPDU), in the grouping transport process, if appearance is congested in the switching/routing node, can abandon the grouping of PLP=1 earlier;

(4) header error control (HEC) field, this field adopts the identical processing of header error control (HEC) with the standard cell, is used for the correctness of guarantee agreement data cell (PDU) header;

(5) there is sign (PCSE) field in the packet checks sequence, and whether this field represents to use packet checks sequence (PCS) that the relevant field of unified framing protocol Data Unit (UFPDU) is carried out error control;

(6) packet-priority territory (PPF) field, this field is used to identify the load packet-priority of unified framing protocol Data Unit (UFPDU), is used for network switch/routing node this protocol Data Unit (PDU) is carried out different processing;

(7) upper-layer protocol identifier (ULPI) field, this field is used for identifying the information such as high level data protocol type of unified framing protocol Data Unit (UFPDU) load;

(8) final stage indication (LSI) field, this field is used to identify a beginning or the middle part that certain load zones of unifying framing protocol Data Unit (UFPDU) is some high-rise User Agreement data cells (PDU), still is the intact part or the last part of some high-rise User Agreement data cells (PDU);

(9) load (Payload) field, this field is used to deposit the part (user data packets) of complete protocol Data Unit of high-rise user (PDU) or protocol Data Unit (PDU), or operation management maintain (OAM) grouping;

(10) packet checks sequence (PCS) field, this field are used for the header of unified framing protocol Data Unit (UFPDU), extension header, data payload area (or only extension header and data payload area) are carried out the error checking and correction protection, and generator polynomial is g (x)=x ³²+ x ²⁶+ x ²²+ x ¹⁶+ x ¹²+ x ¹¹+ x ¹⁰+ x ⁸+ x ⁷+ x ⁵+ x ⁴+ x ²+ x+1.

5. according to claim 1 or 3 described methods, it is characterized in that filling protocol Data Unit (PPDU) has following five kinds of forms:

(1) fills protocol Data Unit form 1, oam (OAM) when being used for the networking of unification framing agreement, this filling protocol Data Unit comprises the header and the load zones of unified framing protocol Data Unit (UFPDU), and the load zones content is identical with the load of the oam (OAM) of asynchronous transfer mode (ATM);

(2) filling protocol Data Unit form 2, is oam (OAM) cell of asynchronous transfer mode (ATM), and the filling protocol Data Unit is identical with oam (OAM) cell of the asynchronous transfer mode (ATM) of standard;

(3) fill protocol Data Unit form 3, be made up of three 8 binary system groups such as " distinctive mark (F) ", spcial character 0xdd (being programmed for other value), " distinctive mark (F) ", this form is applicable to SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) or bare fiber/cable transmission circuit occupancy condition with higher;

(4) fill the protocol Data Unit format 4, comprise the header of unified framing protocol Data Unit (UFPDU), do not have extension header, load zones, packet checks sequence (PCS) field;

(5) filling protocol Data Unit form 5, is asynchronous transfer mode (ATM) idle cell of standard.

6. an elongated packet mixes the adaptive device that transmits with fixed length cell, comprises the following function module:

The business side interface is used for transmission/receiving data frames and cell, realizes that packet/cell transmits and transmit control, protocol Data Unit (PDU) format conversion, and this interface is connected with professional input/output interface, packet/cell push-up storage (FIFO);

Packet/cell push-up storage (FIFO), mainly form by transmission/reception grouping push-up storage (FIFO) and transmission/reception cell push-up storage (FIFO), be used to deposit the grouping and the cell of transmission and receive direction, this memory sends with business side interface, unified framing protocol Data Unit/cell (UFPDU/ATM Cell) or receiving processor is connected;

SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) sends processor, be used for when SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) load mode, to unify protocol Data Unit (PDU) mixed flow that framing protocol Data Unit/cell (UFPDU/ATM Cell) sends the processor input, be mapped to virtual container/empty branch road (VC/VT) of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET), and generation section overhead (SOH) and path overhead (POH), assembling SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) frame is to delivering to the line side interface after this frame scrambling;

The line side interface, be used for SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) is sent processor, or unified framing protocol Data Unit/cell (UFPDU/ATM Cell) sends the input data of processor, carry out parallel/serial exchange, produce tranmitting data register and differential data signals, data-signal is outputed on the circuit; From the physical circuit receiving input data signal, finishing recovery of receive clock signal and data recovers, the serial/parallel conversion of the line data of going forward side by side, according to two kinds of different load modes of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) and bare fiber/cable, send data after the conversion to SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) receiving processor, or unified framing protocol Data Unit/cell (UFPDU/ATM Cell) receiving processor;

SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) receiving processor, the data search that is used for the line side interface is imported is to determine the original position of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) frame, and to the receiving data frames descrambling, take out section overhead (SOH) and path overhead (POH) in this frame, determine the original position of virtual container/empty branch road (VC/VT) original position and first complete protocol Data Unit (PDU) of load zones according to pointer mechanism, again data in the frame are delivered to unified framing protocol Data Unit/cell (UFPDU/ATM Cell) receiving processor;

The expense interface, be used for the setting and the taking-up of complete operation maintenance management (OAM) relevant information, this interface sends processor, SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) receiving processor, unified framing protocol Data Unit/cell (UFPDU/ATM Cell) transmission processor and unification framing protocol Data Unit/cell (UFPDU/ATM Cell) receiving processor with SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) and is connected;

Microprocessor Interface is used to realize be connected with all the other functional modules of external microprocessor, adaptive device, finishes the configuration and the state output of adaptive device;

It is characterized in that also comprising:

Unified framing protocol Data Unit/cell (UFPDU/ATM Cell) sends processor, be used to finish the cell that grouping and cell with packet/cell push-up storage (FIFO) input are packaged into unified framing protocol Data Unit (UFPDU) and modification respectively, the cell that mixes unified framing protocol Data Unit (UFPDU) and revise, add and fill protocol Data Unit (PPDU) to realize rate adapted, and the net load in prepare to pack into virtual container/empty branch road (VC/VT) or the bare fiber/cable transmission circuit carried out transparency processing and scrambling, the output of this transmission processor is connected to SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) and sends processor, or is connected to the line side interface in bare fiber/cable load mode;

Unified framing protocol Data Unit/cell (UFPDU/ATM Cell) receiving processor, be used for virtual container/empty branch road (VC/VT) net load district data to the input of SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) receiving processor, or the data of line side interface input when bare fiber/cable load mode, carry out descrambling, receive and delimit and " going to fill " processing, finishing the header error control (HEC) that receives grouping calculates, unified framing protocol Data Unit (UFPDU) of identification and cell, calculate packet checks sequence (PCS), protocol Data Unit (PPDU) is filled in deletion, correct unified framing protocol Data Unit (UFPDU) and cell are carried out format conversion, output to respectively and receive packet/cell push-up storage (FIFO), output to network components by business side interface transform format again.

7. adaptive device according to claim 6, it is characterized in that unified framing protocol Data Unit/cell (UFPDU/ATM Cell) sends processor and outputs to SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) transmission processor, or when bare fiber/cable load mode, output to the mixed flow of line side interface, form by unified framing protocol Data Unit (UFPDU), cell, filling protocol Data Unit (PPDU) and " distinctive mark (F) " four kinds of protocol Data Units (PDU).

8. adaptive device according to claim 6, it is characterized in that SDH (Synchronous Digital Hierarchy)/Synchronous Optical Network (SDH/SONET) receiving processor, or the line side interface outputs to the mixed flow of unified framing protocol Data Unit/cell (UFPDU/ATM Cell) receiving processor during bare fiber/cable load mode, is made up of unified framing protocol Data Unit (UFPDU), cell, filling protocol Data Unit (PPDU) and " distinctive mark (F) " four kinds of protocol Data Units (PDU).

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