Large particle frame format design method, service processing method and network of metropolitan area transmission network

Abstract

The invention relates to a metropolitan area transmission network large particle frame format design method, a service processing method and a metropolitan area transmission network large particle frame format design network, and relates to the technical field of network design. According to the method, a 5Gbps time slot of a metropolitan area transmission network segment layer is subdivided, a 1Gbps granularity sub-time slot is constructed, and the 1Gbps granularity sub-time slot of the metropolitan area transmission network segment layer is realized by adding time division multiplexing circulation in the 5Gbps time slot of the metropolitan area transmission network segment layer; configuring a 1Gbps granularity sub time slot frame format and an overhead format of the 1Gbps granularity sub time slot; further subdividing the 1Gbps granularity sub time slot of the metro transmission network segment layer through the fine granularity metro transmission network; constructing a kx10Mbps small particle frame format adaptive to the 5Gbps particle time slot and the 1Gbps particle sub time slot; and scheduling each fine-grained time slot by using the overhead so as to realize the transmission of each fine-grained data.

Description

Technical Field

[0001] The present invention relates to the technical field of power network design, and in particular to a method for designing large-granularity frame formats, a service processing method, and a network for a metropolitan area transmission network. Background Art

[0002] Except for relay protection and security control services, various services in the power system have basically been IP-enabled. The dispatching data network and the integrated data network have become the main services consuming bandwidth. When the original SDH technology carries IP services, the bandwidth efficiency is not high, and the maximum rate of SDH is only 10 Gbps, which affects the bearing of IP services. However, relay protection and security control services are the lifelines of the power system, and low-bandwidth dedicated lines based on time slot isolation will serve the power system for a long time. To adapt to the changes in power system services and solve the numerous requirements of current complex network operation and flexible service management, building an end-to-end cost-effective integrated service transmission capacity within the metropolitan area has become an inevitable trend in the development of the power transmission network.

[0003] In terms of technology trends, SPN reuses the robust industrial chain advantages of Ethernet, uses the Ethernet 66B code block kernel as the basis, and expands the TDM time slot cross-networking ability on the basis of large-capacity packet IP devices to provide a more cost-effective end-to-end transmission network for multi-service integrated bearing. As the new power system evolves towards digitalization and intelligence, the power transmission network faces new challenges such as large bandwidth, differential bearing, flexible scheduling, and intelligent operation and maintenance. Relying on its powerful packet capabilities and TDM time division multiplexing technology based on large and small particle time slot cross, SPN constructs a new generation of power transmission network to fully match the differential bearing and hard isolation transmission requirements of various power services. When SPN technology is used in the power transmission network, it can solve many challenges faced during the digital transformation of the power industry and the implementation of the ubiquitous power Internet of Things strategy. The new generation of power communication network networking architecture of SPN is as Figure 1 shown. For the IP-based management large area services with rapid bandwidth growth, SPN packet slicing is used for bearing; for the production control large area services that are sensitive to network jitter and have high network determinacy requirements, the CBR time slot cross-channel of SPN is used for bearing; the end-to-end physical isolation between the SPN cross-channel and the SPN packet slice meets the end-to-end physical isolation requirements between data communication network services, dispatching data network services, and power dedicated line services. Summary of the Invention

[0004] In order to solve the above technical problems or at least partially solve the above technical problems, the present invention provides a method for designing large-granularity frame formats, a service processing method, and a network for a metropolitan area transmission network.

[0005] In a first aspect, the present invention provides a method for designing large-granularity frame formats for a metropolitan area transmission network, including:

[0006] Sub-divide the 5Gbps time slots in the metro transmission network segment layer to construct 1Gbps granular sub-time slots. Among them, the 1Gbps granular sub-time slots in the metro transmission network segment layer are realized by adding time-division multiplexing cycles to the 5Gbps time slots in the metro transmission network segment layer; configure the 1Gbps granular sub-time slot frame format and its overhead format of the 1Gbps granular sub-time slots; further sub-divide the 1Gbps granular sub-time slots in the metro transmission network segment layer into 10Mbps small particle shards through the fine-grained metro transmission network; construct a kx10Mbps small particle frame format that adapts to 5Gbps granular time slots and 1Gbps granular sub-time slots; use overheads at all levels to schedule each fine-grained time slot to achieve each fine-grained data transmission.

[0007] Furthermore, in the time-division multiplexing cycle, the 5Gbps time slot x is divided into sub-time slots x.1, sub-time slots x.2, sub-time slots x.3, sub-time slots x.4, and sub-time slots x.5; in each time slot cycle from time slot 1 to time slot 20 of the 5Gbps time slot, 5x1Gbps granular time slots appear in sequence.

[0008] Furthermore, the overhead of the 1Gbps granular sub-time slot frame in the metro transmission network segment layer realizes the information identification of the 1Gbps granular sub-time slot in the metro transmission network fault layer by extending the use of the reserved bit field segment in the overhead of the 5Gbps granular time slot frame in the metro transmission network segment layer, and only needs to occupy 8 bits of the reserved bit field segment in total.

[0009] Furthermore, the overhead format of the 1Gbps granular sub-time slot frame includes: time slot activation indication (C bit), Client Calendar A, Client Calendar B, time slot adjustment request (CR bit), time slot adjustment response (CA bit), SE-A, SE-B, Granularity, and Sub-slot ID.

[0010] Furthermore, when SE-A is 1, it jointly indicates the information of the 1Gbps sub-time slot configuration table A with the Client Calendar A and Sub-slot ID fields; when SE-B is 1, it jointly indicates the information of the 1Gbps sub-time slot configuration table B with the Client Calendar B and Sub-slot ID fields; when SE-A and SE-B are both 0, the 1Gbps granular time slot is in the deactivated state at this time; the length of Granularity is three bits, and the default is 001, indicating a granularity of 1Gbps; Sub-slot ID: indicates the time slot number of the current sub-time slot.

[0011] Furthermore, when the granularity of the large-grained time slot is 5Gbps, the small-grained multiplexing cycle contains a total of 480 sub-segments and 20 fine-grained basic units, and the valid range of the multi-frame indication field in the fine-grained basic unit overhead is 0 to 19; when the granularity of the large-grained time slot is 1Gbps, the small-grained multiplexing cycle contains a total of 96 sub-segments and 4 fine-grained basic units, and the valid range of the multi-frame indication field in the fine-grained basic unit overhead is 0 to 3.

[0012] In a second aspect, the present invention provides a service processing method, based on the large-granularity frame format design method of the metropolitan area transmission network, comprising:

[0013] On the CBR service access node, execute:

[0014] Step 1: Receive CBR service.

[0015] Step 2: CBR services are mapped into kx10Mbps small-granular channels through the CBR tributary board. In the small-granular time slot cross-connect board, multiple kx10Mbps small-granular channels are multiplexed into the specified time slots in the fine-granular basic unit 0 to the fine-granular basic unit 3, and form a 1G large-granular customer service flow.

[0016] Step 3: Map the 1G customer service flow of the fine-grained basic unit 0 to the fine-grained basic unit 3 into the 1G large-grained time slot, and complete the large-grained time slot multiplexing through the large-grained time slot cross module of the 1G time slot, and then send it to the east-west line board of the SPN network;

[0017] At the intermediate forwarding node of the SPN network, the SPN equipment demultiplexes the 1Gbps large-granularity time slot data corresponding to the 1G large-granularity customer service flow from the interface, and sends the data to the small-granularity time slot cross-connect board, and then demultiplexes the kx10Mbps small-granularity channel data flow in the small-granularity time slot cross-connect board; in the sending direction of the intermediate forwarding node, the small-granularity time slot cross-connect board and the large-granularity time slot cross-connect board complete the step-by-step multiplexing, and send the data to the CBR service egress node;

[0018] At the CBR service egress node, the reverse process of the CBR service access node is completed.

[0019] In the third aspect, the present invention provides a multi-granularity service processing SPN network structure, including: a main control cross board, an east-bound line board, a west-bound line board, a small-granularity time slot cross board, and a CBR branch board that run a large-granularity time slot cross module. The east-bound line boards and the west-bound line boards between different SPN network structures are interconnected via east-west links. The main control cross board, east-bound line board, west-bound line board, small-granularity time slot cross board, and CBR branch board of the SPN network structure implement the service processing method based on the large-granularity frame format design method of the metropolitan area transmission network.

[0020] The above technical solution provided by the embodiments of the present invention has the following advantages compared with the prior art:

[0021] The 5Gbps time slots in the metropolitan area transmission network segment layer are subdivided to construct 1Gbps granular sub-time slots. Among them, the 1Gbps granular sub-time slots in the metropolitan area transmission network segment layer are realized by adding time-division multiplexing cycles in the 5Gbps time slots in the metropolitan area transmission network segment layer; configure the 1Gbps granular sub-time slot frame format and its overhead format of the 1Gbps granular sub-time slot; further subdivide the 1Gbps granular sub-time slots in the metropolitan area transmission network segment layer into 10Mbps small particle shards through a fine-grained metropolitan area transmission network; construct a kx10Mbps small particle frame format that adapts to 5Gbps granular time slots and 1Gbps granular sub-time slots; use overhead to schedule each fine-grained time slot to achieve each fine-grained data transmission. Under the solution of this application, when the large particles support 5G, the 8-route networking requires at least 50G small particle service board capacity; when the large particles support 1G, the 8-route networking requires at least 18G small particle service board capacity. This solution can greatly improve the networking and evolution capabilities of SPN in the power grid scenario. Improvement of network transmission flexibility: By allocating 96 sub-shards for the 1Gbps sub-time slot to adapt to medium and low bandwidth services (such as power monitoring), it reduces the bandwidth waste caused by the 5Gbps fixed granularity. At the same time, the number of fine-grained basic units allocated for the 1Gbps sub-time slot is less than the number of fine-grained basic units allocated for the 5Gbps time slot, which speeds up the time slot adjustment response speed.

[0022] This application multiplexes the existing overhead fields in the metropolitan area transmission network segment to ensure compatibility with the existing metropolitan area transmission network. This application supports online time slot adjustment through the SE-A / SE-B switching sub-time slot configuration table, and supports SE-A / SE-B configuration 0, so that the 1Gbps granular time slot is disabled and restored to the 5Gbps granular time slot, and the dynamic adjustment of the metropolitan area transmission network time slot configuration table is restored. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The drawings here are incorporated into the description and form a part of this description, showing embodiments that conform to the present invention and are used together with the description to explain the principles of the present invention.

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, for those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the schematic diagram of the channel layer and segment layer of the metropolitan area transport network;

[0026] Figure 2 Schematic diagram of the basic data unit of the metropolitan area transmission network segment layer with a granularity of 5 Gbps for a 100G instance;

[0027] Figure 3 Schematic diagram of the basic data unit of the metropolitan area transmission network segment layer with a granularity of 5 Gbps for a 50G instance;

[0028] Figure 4 Schematic diagram of the instance frame of the metropolitan area transmission network segment layer;

[0029] Figure 5 Schematic diagram of the multiple-frame of the metropolitan area transmission network segment layer for a 100G instance;

[0030] Figure 6 Schematic diagram of the multiple-frame of the metropolitan area transmission network segment layer for a 50G instance;

[0031] Figure 7 Schematic diagram of the Calendar dynamic negotiation of the metropolitan area transmission network;

[0032] Figure 8 Schematic diagram of the code block of the fine-grained channel of the fine-grained metropolitan area transmission network;

[0033] Figure 9 Schematic diagram of the multiplexing process of the FGU of the fine-grained metropolitan area transmission network;

[0034] Figure 10 Schematic diagram of the relationship between the fine-grained basic unit sequence and the metropolitan area transmission network interface in the 5 Gbps service channel of the 100G metropolitan area transmission network instance;

[0035] Figure 11 Schematic diagram of the composition structure of the fine-grained basic unit when transmitted through a 10GE interface;

[0036] Figure 12 Schematic diagram of the format of the fine-grained basic unit of the fine-grained metropolitan area transmission network;

[0037] Figure 13 Schematic diagram of the encapsulation and mapping of the fine-grained service to form the fine-grained basic unit;

[0038] Figure 14 Schematic diagram of the overhead of each fine-grained basic unit;

[0039] Figure 15 Schematic diagram of the GCC filling method;

[0040] Figure 16 Schematic diagram of the CRC calculation;

[0041] Figure 17 Schematic diagram of the encapsulation and mapping of the fine-grained service to form the fine-grained basic unit;

[0042] Figure 18 This is a schematic diagram of the frame overhead of 1Gbps granular sub - time slots provided by an embodiment of the present invention;

[0043] Figure 19 This is a schematic diagram of the corresponding relationship between 1Gbps granular sub - time slots and fine - grained basic units provided by an embodiment of the present invention;

[0044] Figure 20 This is a schematic diagram of the corresponding relationship between 5Gbps granular time slots and fine - grained basic units provided by an embodiment of the present invention;

[0045] Figure 21 This is a flowchart of a service processing method provided by an embodiment of the present invention;

[0046] Figure 22 This is a schematic diagram of a multi - granularity service - processing SPN network structure provided by an embodiment of the present invention. Detailed implementation manners

[0047] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0048] It should be noted that in this article, the terms "include", "comprise" or any other variant thereof are intended to cover non - exclusive inclusion, so that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, an element defined by the phrase "including a..." does not exclude the existence of additional identical elements in the process, method, article or device including the said element.

[0049] To clearly illustrate the technical solution of this application, first, SPN (Slicing Packet Network) and MTN (Metro Transport Network) are introduced. The main network layering architecture of SPN includes:

[0050] Slicing Packet Layer (SPL): It realizes the addressing, forwarding, and bearer pipeline encapsulation of IP, Ethernet, and CBR (Constant BitRate) services, and provides various service types such as L2VPN, L3VPN, and CBR transparent transmission.

[0051] Slicing Channel Layer (SCL): It adopts the MTN channel layer and MTN section layer technologies based on TDM time slots to provide end-to-end channels for network services and slices.

[0052] Slicing Transport Layer (STL): It is used to provide IEEE 802.3 Ethernet physical layer encoding and decoding and optical transmission medium processing, and realizes efficient large-bandwidth transmission capabilities.

[0053] In the above architecture, the MTN technology mainly realizes the metro transport network channel layer (MTN path) and the metro transport network section layer (MTN Section). The MTN technology extends the ability of Ethernet slices based on the native Ethernet kernel, which can not only be fully compatible with Ethernet but also avoid packet traversing the L2 / L3 storage look-up table, thus providing the L1 channel networking ability with deterministic low latency and hard pipe isolation. The metro transport network section layer is located between the metro transport network channel layer and the IEEE 802.3 Ethernet PHY layer of the slicing transport layer, and realizes the rate adaptation of the access data stream of the metro transport network channel layer, the mapping and demapping, multiplexing and demultiplexing, and frame overhead insertion and extraction functions of the data stream on the section layer, provides hard pipe isolation and OAM monitoring technology, and complies with the OIF FlexE 2.0 and FlexE 2.1 specifications. The specific technical requirements include: supporting N PHY members to be bound to a metro transport network interface group, N≥1. When the number of members in the interface group is greater than 1, it is required to support the tolerable delay difference of each bound PHY not less than 2us; the alignment of N members in the interface group and the detection mechanism for lost alignment; the mechanism for supporting the physical layer detection alarm and error notification of PHY members to the metro transport network interface group; supporting the frequency offset and rate adaptation between the metro transport network Client and the metro transport network section layer and the metro transport network interface; supporting the metro transport network Client to access any one or more relevant time slots within the metro transport network interface; supporting two modes of static configuration and dynamic negotiation of the time slot allocation table. MTN is located between the physical layer and the data link layer of traditional network technologies. Specifically, MTN embeds the metro transport network channel layer and the metro transport network section layer in the physical coding sublayer of traditional network technologies, dividing the physical coding sublayer into upper and lower layers.

[0054] Both the channel layer and section layer of the metropolitan area transport network are designed based on 66B code blocks. The 66B code blocks derived from the Ethernet frame content are used as units for TDM (Time Division Multiplex) time slotting and switching, achieving hard slice isolation.

[0055] Figure 1 In it, the 66B code blocks obtained by encoding the ABC Ethernet frame are divided. The 66B code block A, 66B code block B, and 66B code block C respectively belong to the original Ethernet frame A, Ethernet frame B, and Ethernet frame C. After decoding, each 66B code block A, 66B code block B, and 66B code block C can form the complete Ethernet frame A, Ethernet frame B, and Ethernet frame C. Different channels in the channel layer of the metropolitan area transport network upload the 66B code blocks belonging to different Ethernet frames in the corresponding time slots in a fixed order. The rate matching of the channels in the metropolitan area transport network occupies the number of time slots of the section layer frame of the metropolitan area transport network. The 66B code blocks of the channels at the transmitting end are sequentially mapped one by one into the time slots of the section layer of the metropolitan area transport network and sent to the receiving end PHY through the transmitting end PHY; after receiving the data, the receiving end PHY sends it to the corresponding time slots of the section layer of the metropolitan area transport network for demapping, and recovers the 66B code block sequence of the transmitting end from the MTN section layer frame. The 66B code blocks belonging to different Ethernet frames can be transmitted in a non-interfering and isolated manner during the transmission of the MTN section layer link because the positions of the time slots are fixed.

[0056] The basic data unit (BDU) frame format of the 5Gbps granularity section layer of the metropolitan area transport network includes: one overhead 66B code block and 20460 payload 66B code blocks; for 5Gbps granularity, as Figure 2 shown, the payload of the 100G instance-based section layer of the metropolitan area transport network has 20×1023 code blocks, as Figure 3 shown, the payload of the 50G instance-based section layer of the metropolitan area transport network has 10×1023×2 code blocks.

[0057] As Figure 4 shown, 8 basic data units (BDUs) of the section layer of the metropolitan area transport network form an instance frame; further, as Figure 5 shown, for the 100G instance, 32 instance frames of the section layer of the metropolitan area transport network form a multiplex frame, which is an 8×20461×32×66B information structure; as Figure 6 shown, for the 50G instance, 16 instance frames of the section layer of the metropolitan area transport network form a multiplex frame, which is an 8×20461×16×66B information structure.

[0058] The static configuration of Calendar refers to the selection of the service recovery configuration of the Client of the receiving-end metro transmission network corresponding to the two interconnected metro transmission network interface groups. The extraction of the metro transmission network Client is completely based on the configuration information issued by the local controller, rather than the configuration information extracted from the Client Calendar A / B fields of the metro transmission network interface overhead at the receiving end. The correctness of the Client interconnection configuration is guaranteed by the controller, and the configuration information extracted from the Client Calendar A / B fields can be used for consistency verification.

[0059] The dynamic negotiation of Calendar follows Section 7.3.4 of OIF FlexE v2.0. The dynamic negotiation of Calendar refers to the service recovery of the metro transmission network Client corresponding to the two interconnected metro transmission network interfaces. The extraction of the Client is completely realized through negotiation based on the information in the C, CR, CA, and Client Calendar A / B fields of the metro transmission network interface overhead. The processing flow is as Figure 7 shown.

[0060] When the Client configuration sent by the metro transmission network interface group A uses Client Calendar A, corresponding to C = 0 and CR = 0; the specific operation steps of the Calendar dynamic negotiation are as follows:

[0061] Step 1: The metro transmission network interface group A updates the configuration information of Client Calendar B at the sending end;

[0062] Step 2: The metro transmission network interface group A sets CR = 1 at the sending end and waits for the metro transmission network interface group B to feedback the CA information; a timeout processing mechanism is introduced in Step 2 to confirm the timeliness of the CA feedback and avoid exceptions. The default recommended timeout is 1 s, and the timeout can be configured. If the CA information is not received after the timeout, an alarm is reported for easy operation and maintenance.

[0063] Step 3: After receiving CR = 1, the metro transmission network interface group B checks the legality of the configuration information extracted from Client Calendar B. If it meets the rules, it sets CA = 1;

[0064] Step 4: After receiving CA = 1, the metro transmission network interface group A sets C = 1 and sends it;

[0065] Step 5: The metro transmission network interface group A switches the FlexE Client service configuration, enables the configuration information of Client Calendar B, and sends the service. The metro transmission network interface group B enables the configuration information of Client Calendar B to extract the service.

[0066] The metropolitan area transport network interface group supports binding multiple physical PHY layer links, and the metropolitan area transport network Client is carried on the bundled MEN interface group link. The time slots corresponding to a metropolitan area transport network Client can be distributed on different PHYs within the metropolitan area transport network interface group. When some PHY links fail, the metropolitan area transport network Clients that have nothing to do with the faulty PHY links can be transmitted normally; the time slots of the metropolitan area transport network Clients related to the faulty PHY links need to be isolated to implement the fault isolation function in the case of multi-PHY binding of the metropolitan area transport network interface group.

[0067] The OAM functions, OAM frame formats, and OAM mechanisms of the metropolitan area transport network Section layer follow the specific specifications of OIF FlexE 2.0 and OIF FlexE 2.1. The overhead and alarm function requirements implemented by the OAM monitoring technology supported by the metropolitan area transport network section layer are as follows:

[0068] It is necessary to implement the Group_Number_Mismatch (GNM) alarm for the metropolitan area transport network interface group number mismatch: Each metropolitan area transport network interface group has a 20-bit group number. All members within an interface group must have the same group number. When the group number in the overhead frame with correct CRC check received by any member interface within the interface group is inconsistent with the configured expected value, the Group_Number_Mismatch alarm for the metropolitan area transport network interface group will be generated, that is, the Group_Number_Mismatch alarm for the metropolitan area transport network interface group; and when the group numbers in the overhead frames with correct CRC check received by all member interfaces are in line with the configured expected values, this alarm is cleared.

[0069] It is necessary to implement the Loss of Group Alignment (LOGA) alarm: When any abnormality occurs in any member PHY instance in a metropolitan area transport network interface group, such as signal loss, 66B code block positioning, frame loss, multiframe loss, delay exceeding the standard, etc., resulting in the incorrect recovery of the metropolitan area transport network section layer, the Loss of Group Alignment alarm is reported. When all members of the metropolitan area transport network interface group are working properly, the Loss of Group Alignment alarm is cleared.

[0070] It is necessary to implement the Map Mismatch (MM) alarm for the metro transmission network: 32 or 16 overhead multiplex frames form a complete Map field of the metro transmission network. The position values of the bits with '1' in the Map of the metro transmission network correspond to the values of the PHY instance numbers. A complete Map of the metro transmission network is carried in all the metro transmission network interface PHY instances within the interface group. When the member interfaces of the interface group receive an overhead multiplex frame with correct CRC check, if the Map of the metro transmission network received by any PHY instance member within the interface group is inconsistent with the expected Map of the metro transmission network, or the received PHY instance number value has no corresponding bit in the expected Map of the metro transmission network, or the received PHY instance numbers of different PHY instances within the group are equal, then the Map Mismatch alarm for the metro transmission network is generated.

[0071] It is necessary to implement the Instance_Number_Mismatch (INM) alarm: When the PHY instance number in the overhead frame with correct CRC check received by the member interfaces of the interface group is inconsistent with the expected value configured at the receiving end, the Instance_Number_Mismatch alarm is generated. When the instance number in the overhead frame with correct CRC check received by the member interface conforms to the expected value configured at the receiving end, the Instance_Number_Mismatch alarm is cleared.

[0072] It is necessary to implement the Loss of MTN Section Overheadframe (LOF) alarm for the metro transmission network: There are the following two detection mechanisms for LOF:

[0073] If the synchronization header, control block type, or O code of the metro transmission network section layer frame does not match at the expected position 5 times, then the Loss of MTN Section Overheadframe alarm is generated.

[0074] According to the specifications of ITU-T G.798.1 and G.8023, when the receiving end is in the out-of-frame (OOF) state for 3 ms, it enters the frame loss state. When the receiving end is in the in-frame state for 3 ms, the frame loss state is cleared. The out-of-frame state is an intermediate transition state. When the synchronization header (2 bits: 10), control block type (0x4b), and "O" code field (0x5) in the first code block of the metro transmission network section layer overhead frame do not match 5 times, the receiving end enters the out-of-frame state. When a legal and valid first code block is detected in two consecutive FlexE overhead frames, the out-of-frame state is exited and the in-frame state is entered.

[0075] It is necessary to implement the Loss of Multi-frame (LOMF) alarm at the metro transport section layer (MTN Section overhead Loss of Multi-frame): There are the following two detection mechanisms for the Loss of Multi-frame alarm at the metro transport section layer:

[0076] For the multi-frame at the metro transport section layer, when the receiving end fails to detect the change of the OMF bit from "0" to "1" or from "1" to "0" in two consecutive metro transport section overhead frames with correct CRCs as expected, it enters the Loss of Multi-frame alarm state at the metro transport section layer.

[0077] The multi-frame at the metro transport section layer is composed of 32 or 16 basic frame structure units of the metro transport section overhead. The synchronization of the multi-frame at the metro transport section layer can be achieved by locating the OMF bit in the metro transport section overhead frame. The OMF bits in the first 16 / 8 metro transport section overhead frames in the multi-frame at the metro transport section layer are "0", and the OMF bits in the last 16 / 8 metro transport section overhead frames in the multi-frame at the metro transport section layer are "1".

[0078] When the CRC is correct, when in the IN-multiframe state, if the OMF bit transition does not occur as expected for two consecutive times, it enters the Loss of Multi-frame state; when the CRC is correct, when in the Out-Ofmultiframe state, if the Out-of-multiframe bit transition occurs as expected for two consecutive times, it enters the IN-multiframe state.

[0079] According to the specifications of ITU-T G.798.1 and G.8023, when the receiving end is in the Out-of-multiframe state for 10 ms continuously, it enters the Loss of Multi-frame state; when the receiving end enters the IN-multiframe state, the Loss of Multi-frame state is cleared immediately.

[0080] It is necessary to implement the Remote PHY Fault (RPF) alarm: At the receiving end, when the member interface detects a local PHY fault, such as signal loss, 01 header block lock failure, AM lock failure, high bit error rate, or other PCS layer alarms, the Remote PHY Fault bit in the first instance overhead frame in the transmitted PHY is set to 1 to notify the remote metro transport section layer of the local PHY fault.

[0081] It is necessary to implement the alarm for Client Calendar Mismatch (CCM): Each PHY instance at the metro transmission network segment layer has two time slot configurations, Calendar A / B. The currently used configuration is specified by the C-bit overhead. Calendar A / B is transmitted in the 3rd block of the first 20 / 10 overhead frames in the overhead multiframe at the metro transmission network segment layer, indicating the corresponding metro transmission network Client number in the time slot. Calendar A / B is 16 bits. A value of 0x0000 indicates that the corresponding time slot is unused (but available), and a value of 0xFFFF indicates that the corresponding time slot is unavailable. When there is a CRC error, it remains unchanged.

[0082] The alarm for Client Calendar Mismatch is cleared when a new CC / CCA / CCB value is received by a certain PHY instance at the metro transmission network segment layer, and the received CC / CCA / CCB and the expected CC / CCA / CCB time slot configuration values are compared:

[0083] When both the received CC and the expected CC values are '0', and the valid client number values (i.e., not 0x00000 or 0xfffff) of the same time slot allocation in the received CCA and the expected CCA are not equal, a CCAM alarm for that time slot is generated;

[0084] When both the received CC and the expected CC values are '1', and the valid client number values (i.e., not 0x00000 or 0xfffff) of the same time slot allocation in the received CCB and the expected CCB are not equal, a CCBM alarm for that time slot is generated.

[0085] If a CCAM alarm for Calendar A or a CCBM alarm for Calendar B occurs, a CCM alarm is generated.

[0086] The OAM overhead performance error events supported by the metro transmission network segment layer include:

[0087] Overhead CRC check error CRC16E (CRC16 check error):

[0088] When a CRC16 check error occurs in the frame overhead, a CRC check error event is reported once. It is cleared when the CRC16 check in the frame overhead is correct. The number of occurrences of CRC check errors can be accumulated.

[0089] Skew Tolerance Error (STE) of the component member delay difference:

[0090] When the time difference between the earliest-arriving member PHY and the latest-arriving member PHY in a metro transport network interface group exceeds the threshold or the buffer capacity, resulting in the inability to restore the member sorting, a member delay difference tolerance error event prompt is generated. When the time difference between the earliest-arriving member PHY and the latest-arriving member PHY in a metro transport network interface group is within the predetermined threshold and does not affect the member sorting restoration, the error event disappears.

[0091] Overhead C-bit error CBE (C-bit error):

[0092] In the overhead of a metro transport network section layer frame, when the contents of three C bits are inconsistent, a C-bit error is generated once. In the overhead of a metro transport network section layer frame, when the contents of the three C bits are the same, the error disappears. The number of accumulated C-bit errors is supported.

[0093] The fine-grained metro transport network fgMTN introduces the FGU (Fine Granularity Unit) layer to achieve finer-grained transmission, such as Figure 8 shown. The fine-grained channels of the fine-grained metro transport network are composed of a continuous sequence of 66B code blocks. The OAM of the fine-grained channels follows the OAM functions, insertion, and extraction methods of the metro transport network channel layer, with differences in format.

[0094] The FGU frame structure of the fine-grained basic unit sequence (fg-BU) conforms to the provisions of the 66B coding type in Clause 82 of IEEE 802.3. When transmitting in the service channel of the metro transport network channel layer, the rate adaptation can be achieved by adding or deleting Idle code blocks between the fine-grained basic units. The OAM code blocks of the metro transport network channel layer are located between the fine-grained basic units. The fine-grained basic unit has a fixed length, including a start (S0) code block, 195 data (D) code blocks, and an end (T7) code block, with a total length of 197 66B code blocks. When the FGU passes through a 10GE interface, no transcoding operation from S0 to S4 is performed, and it continues to be the S0 code block. The start (S0) code block is compatible with the Ethernet preamble and frame delimiter standards. The 195 data code blocks and the end (T7) code block provide a data area of 195×8 + 7 bytes. The data area is used to carry the overhead and payload content with a total length of 1567 bytes, including 7 bytes of multiplexing interface overhead and 1560 bytes of payload. The format of the fine-grained basic unit is as Figure 12 shown.

[0095] FGU multiplexing process: The FGU layer realizes finer-grained transmission by transmitting the fine-grained basic unit sequence through the service channels of the 5Gbps channel layer of the metropolitan area transmission network. In the service channels of the 5Gbps metropolitan area transmission network, the fine-grained basic unit sequence can provide 480 sub-slots of 10Mbps for carrying fine-grained channel signals. The fine-grained channel with a bandwidth of N×10Mbps will occupy N sub-slot shards. The multiplexing process of FGU is as Figure 9 shown. The 66B code blocks of customer services A, B......Z are mapped into one or more sub-slot time slots. After code block compression, every 24 sub-slots are mapped into the payload area of the fine-grained basic unit frame.

[0096] Taking the 100G metropolitan area transmission network example, the relationship between the fine-grained basic unit sequence and the metropolitan area transmission network interface is as Figure 10 shown. In addition to the service channels of the 5Gbps metropolitan area transmission network, every 40 fine-grained basic units can also form a multiframe for transmission in the 10GE interface, as specifically shown in Figure 11 shown. For the 5Gbps transmission bandwidth provided by the channel layer service channel, one fine-grained basic unit contains 24 sub-slots, each sub-slot is 65 bytes, and can carry 8 65B code blocks. Each sub-slot can be independently allocated to a fine-grained Sub-client for use. 20 fine-grained basic units form a multiframe, and 24×20 = 480 sub-slots are provided within the multiframe. The total bandwidth value of each sub-slot is 10.101Mbps, including packet customer signals or CBR customer signals, OAM information, IDLE. The bandwidth available for carrying customer signals (including ETH customer signals and CBR customer signals) is 10Mbps. When the 10GE physical interface carries FGU, 40 fine-grained basic units form a multiframe, and 24×40 = 960 sub-slots are provided within the multiframe. The total bandwidth value of each sub-slot is 10.101Mbps (including customer signals, OAM information, Idle). The bandwidth available for carrying customer signals (including ETH customer signals and CBR customer signals) is 10Mbps. The number of sub-slots occupied by the small-granularity Client of the metropolitan area transmission network on the 10GE interface shall not exceed 480. Each sub-slot carries 8 66B code blocks from the corresponding service (using the 66B coding type in Chapter 82 of IEEE 802.3). The unused time slots not allocated to the service are filled with 8 Error code blocks. The total of 24×8 = 192 66B code blocks of 24 sub-slots are compressed through the synchronization header from 66B to 65B (where the first bit of the 65B is 0 indicating a data code block and 1 indicating a control code block), and filled into the payload time slot. After adding 7-byte overhead, they are sequentially filled into the payloads of the D code block and T7 code block of the fine-grained basic unit. As Figure 13As shown, for each Sub-slot, the 65B code block received first is sent first; for each 65B code block, the compressed sync header is sent first, and the remaining 64 bits shall comply with the provisions of IEEE 802.3, and the LSB of each field is sent first.

[0097] During the forwarding process of the fine-grained channel, when performing rate adaptation and online bandwidth lossless adjustment, the addition and deletion of Idle code blocks can only be performed at the IPG position.

[0098] FGU frame overhead definition:

[0099] Each fine-grained basic unit has 56-bit overhead, and the payload area bits 0 to 55 of the first 66B data code block, and the specific format is as Figure 14 , including multi-frame indication (MFI), overhead channel usage indication (Flag), time slot increase adjustment notice (S bit), time slot effective indication (C bit), time slot adjustment request (CR bit), time slot adjustment response (CA bit), GCC channel, Client ID, Sub-slot ID, CRC. Among them, the GCC channel shares bit positions with Client ID and Sub-slot ID. When the Flag value is 11, the corresponding bit positions after CA are used for the GCC channel. When the Flag value is 00, it means that the corresponding bit positions are used for Client ID and Sub-slot ID.

[0100] The specific meanings of the FGU frame overhead fields are as follows:

[0101] Multi-frame indication (MFI): 6 bits in length, used to indicate the number of each fine-grained basic unit in the multi-frame. For the first fine-grained basic unit in the multi-frame, 0 is filled, and the MFI value of the subsequent fine-grained basic units increases by 1 in sequence. For the 5Gbps channel, the MFI value range is 0 to 19; for the 10GE interface, the MFI value range is 0 to 39.

[0102] Overhead channel usage indication (Flag): 2 bits in length, used to indicate whether the 33-bit position after CA is used for GCC or Client ID and Sub-slot ID. When the Flag value is 11, it means Figure 12The corresponding bit positions after CA are used for the GCC channel. When the Flag value is 00, it means the corresponding bit positions are used for the Client ID and Sub-slot ID. When there is a time slot adjustment requirement, only when the Flag value is 00, the S, C, CR, and CA bit positions may carry valid information with a value of 1. After the information with a value of 1 in the S, C, CR, and CA bit positions has been sent, the Flag value in the overhead will be restored to 11, and the S, C, CR, and CA bit positions will be restored to the default value of 0. The overheads of two consecutive frames composed of even frames with MFI = n (n = 0, 2, 4,...) and odd frames with MFI = n + 1 in the multi-frame have the same Flag value. When the Flag value of the overheads of two consecutive frames is 00, if there is no lossless adjustment message transmission in the overhead of the latter frame at the transmitting end, the S, C, CR, and CA bit positions are 0, and the Client ID and Sub-slot ID fields are invalid, and the receiving end ignores them. In the case of neither bandwidth adjustment nor management channel information, the Flag field is filled with the value 11, and the GCC content is filled with the Idle code block.

[0103] Time slot increase adjustment notice (S bit position): 1 bit length, used for the downstream to notify the upstream to start adjustment during time slot increase adjustment. When the S bit position is 1, the corresponding overhead Flag should be 00, and the Client ID involved in the adjustment is carried in the overhead, and the Sub-slot ID field is reserved (filled with 0 by the transmitting end and not forced to be detected by the receiving end).

[0104] Time slot effective indication (C bit position): 1 bit length, used for the time slot adjustment to take effect. After receiving CA, the adjusted time slot takes effect, and at this time, the C bit positions of the first three fine-grained basic units of a certain multi-frame are all set to 1 and sent. When the C bit position is 1, the corresponding overhead Flag should be 00, and the Client ID and Sub-slot ID information involved in the adjustment are carried in the overhead. When the bandwidth decreases, the Client ID is all zeros.

[0105] Time slot adjustment request (CR bit position): 1 bit length, used to send a time slot adjustment request. At this time, the CR bit positions of a certain fine-grained basic unit are all set to 1 and sent. When the CR bit position is 1, the corresponding overhead Flag should be 00, and the Client ID and Sub-slot ID information involved in the adjustment are carried in the overhead. When the bandwidth decreases, the Client ID is all zeros. After the CR message is sent, set the CA response timeout timer to 1 s. If there is no CA response after the timeout, the CR message is retransmitted. The maximum number of retransmissions of the CR message is 3 times.

[0106] Timing Adjustment Response (CA bit): 1 bit in length, used for the timing adjustment response after receiving the CR. At this time, the CA bits of a certain fine-grained basic unit are all set to 1 and sent. When the CA bit is 1, the corresponding overhead Flag should be 00, and the Client ID and Sub-slot ID information related to the adjustment are carried in the overhead. When the bandwidth is reduced, the Client ID is all zeros.

[0107] GCC Channel: 33 bits in length, used for transmitting management information, etc. The information transmission adopts the Ethernet packet format and should comply with the provisions of the IEEE 802.3 66B coding format in Chapter 82. According to the IEEE 802.3 bit transmission order of the 66B code block output by the encoder, the first 33 bits (bits 0 to 32, including the synchronization header) and the last 33 bits are sent on the GCC successively. It is necessary to send the first 33 bits (bits 0 to 32, including the synchronization header) in the even frames with MFI = n (n = 0, 2, 4,...) in the multi-frame first, and send the last 33 bits in the odd frames with MFI = n + 1. When the Flag field is 11 and there is no transmission of management channel information, the GCC content is filled with the Idle code block. See the GCC filling method in Figure 15 .

[0108] Client ID: 12 bits in length, the two high bits of the MSB are reserved, and currently only the last 10 bits are used temporarily. For the 5Gbps channel, the Client ID value can be updated segment by segment. When the Client ID bit value is all 0, it means not in use. The value with all 1 Client ID bits is reserved. The value with neither all 0 nor all 1 Client ID bits is a valid value and can be used normally.

[0109] Sub-slot ID: 12 bits in length, the two high bits of the MSB are reserved, and currently only the last 10 bits are used temporarily. For the 5Gbps channel, the Sub-slot ID value range is 0 to 479, and the value with all 1 bits is reserved; for the case where the FGU is carried on the 10GE interface, the Sub-slot ID value range is 0 to 959, and the value with all 1 bits is reserved.

[0110] CRC: 7 bits in length, generated by calculating the first 41 bits (including the fields after the Flag, excluding the first 2 reserved bits and 6-bit MFI). The first sent bit is used as the high bit (x40) for calculation. CRC7 polynomial: x7 + x5 + x4 + x2 + x + 1, with an initial value of 0. The CRC7 result [x6:x0] is sent with the high bit (x6) first. CRC7 calculation example: Request to allocate time slot #308 to service #291, as Figure 16 shown.

[0111] The current number of access services is not large enough, resulting in a waste of 5G time slot bandwidth. An 8-way routing network requires at least a 50G small-granularity service board capacity. For the power scenario, a 5Gbps large-granularity time slot granularity is not economically efficient. There is a need for a technology that can not only conform to the current technical architecture but also enhance the networking and evolution capabilities in the power scenario.

[0112] Embodiment 1

[0113] To solve the above problems, the present invention provides a method for designing a large-granularity frame format for a metropolitan area transmission network. The present application designs a new large-granularity frame format and its corresponding overhead format, providing a 1Gbps large-granularity time slot granularity transmission capability based on a 5Gbps time slot. At the same time, for the 1Gbps large-granularity time slot, the kx10Mbps small-granularity frame format is transformed to provide a 10Mbps granularity transmission capability. A method for designing a large-granularity frame format for a metropolitan area transmission network includes:

[0114] As Figure 17 shown, the 5Gbps time slot in the metropolitan area transmission network section layer is further subdivided to construct 1Gbps granularity sub-time slots. Among them, the 1Gbps granularity sub-time slots in the metropolitan area transmission network section layer are realized by adding time division multiplexing cycles to the 5Gbps time slots in the metropolitan area transmission network section layer. The 5Gbps time slot x is divided into time slot x.1 (occupying 1Gbps), time slot x.2 (occupying 1Gbps), time slot x.3 (occupying 1Gbps), time slot x.4 (occupying 1Gbps), and time slot x.5 (occupying 1Gbps). In each cycle of the 5Gbps time slots from time slot 1 to time slot 20, the 5x1Gbps granularity time slot sub-time slots x.1, sub-time slot x.2, sub-time slot x.3, sub-time slot x.4, and sub-time slot x.5 appear in sequence.

[0115] Configure the 1Gbps granularity sub-time slot frame format and its overhead format for the 1Gbps granularity sub-time slot.

[0116] The overhead of the 1Gbps granularity time slot frame in the metropolitan area transmission network section layer extends the reserved bit field in the 5Gbps granularity time slot frame overhead of the metropolitan area transmission network section layer to realize the information identification of the 1Gbps granularity time slot in the metropolitan area transmission network fault, and only 8 bits of the reserved bit field are required in total.

[0117] The overhead of the 1Gbps granularity time slot frame includes: time slot activation indication (C bit), Client Calendar A, Client Calendar B, time slot adjustment request (CR bit), time slot adjustment response (CA bit), SE-A, SE-B, Granularity, and Sub-slot ID.

[0118] When SE-A is 1, it jointly indicates the information of Sub-slot Configuration Table A of 1Gbps in combination with Client Time Slot Configuration Table A and Sub-slot ID field. When both SE-A and SE-B are 0, the 1Gbps granular time slot is in the de-enabled state.

[0119] When SE-B is 1, it jointly indicates the information of Sub-slot Configuration Table B of 1Gbps in combination with Client Time Slot Configuration Table B and Sub-slot ID field. When both SE-A and SE-B are 0, the 1Gbps granular time slot is in the de-enabled state.

[0120] Granularity: Three-bit length, default is 001, indicating that the FlexE granularity is 1Gbps at this time.

[0121] Sub-slot ID: Indicates the time slot number of the current sub-slot.

[0122] The SE-A / SE-B fields cooperate with the Sub-slot ID and Client Calendar A / Client Calendar B fields, supplemented by the multi-frame indication in the frame overhead of the metro transport network segment, to indicate Sub-slot Configuration Tables A and B of 1Gbps in the metro transport network segment. The sub-slot configuration related information is allocated in 5 multi-frames. Specifically as Figure 18 shown. The processing of Sub-slot Configuration Table A / B is similar to the processing flow of the 5Gbps time slot configuration table in the metro transport network segment layer.

[0123] Construct a kx10Mbps small-granularity frame format that adapts to 5Gbps granular time slots and 1Gbps granular sub-time slots.

[0124] When the granularity of the large-granularity time slot is 5Gbps, there are a total of 480 sub-fragments and 20 fine-grained basic units in the small-granularity multiplexing cycle. The valid range of the multi-frame indication field segment in the fine-grained basic unit overhead is 0 to 19, as Figure 19 shown.

[0125] When the granularity of the large-granularity time slot is 1Gbps, there are a total of 96 sub-fragments and 4 fine-grained basic units in the small-granularity multiplexing cycle; at the same time, the valid range of the multi-frame indication field segment in the fine-grained basic unit overhead changes from 0 to 19 to 0 to 3, as Figure 20 shown.

[0126] The sub-slot configuration related information is allocated in 5 multi-frames.

[0127] Embodiment 2

[0128] As Figure 21As shown, an embodiment of the present invention provides a service processing method, based on the large-granularity frame format design method of the metropolitan area transmission network, comprising:

[0129] On the CBR service access node, execute:

[0130] Step 1: Receive CBR service.

[0131] Step 2: CBR services are mapped into kx10Mbps small-granular channels through the CBR tributary board. In the small-granular time slot cross-connect board, multiple kx10Mbps small-granular channels are multiplexed into the specified time slots in the fine-granular basic unit 0 to the fine-granular basic unit 3, and form a 1G large-granular customer service flow.

[0132] Step 3: Map the 1G customer service flow of fine-grained basic unit 0 to fine-grained basic unit 3 into the 1G large-grained time slot, and complete the multiplexing of 5 1G granular time slots to 1 5G large-grained time slot through the large-grained time slot cross module of the 1G granular time slot to form a 5G large-grained data flow. At the same time, the Granularity field in the large-grained frame overhead is set to 001, and finally sent to the east-west line board of the SPN network;

[0133] At the intermediate forwarding node of the SPN network, the SPN equipment demultiplexes the 1Gbps large-granularity time slot data corresponding to the 1G large-granularity customer service flow from the interface, and sends the data to the small-granularity time slot cross-connect board, and then demultiplexes the kx10Mbps small-granularity channel data flow in the small-granularity time slot cross-connect board; in the sending direction of the intermediate forwarding node, the small-granularity time slot cross-connect board and the large-granularity time slot cross-connect board complete the step-by-step multiplexing, and send the data to the CBR service egress node;

[0134] At the CBR service egress node, the reverse process of the CBR service access node is completed, including:

[0135] After receiving the data from the upstream node through the Ethernet port, the egress node identifies the large-granularity frame structure of the metropolitan area transmission network and demultiplexes the large-granularity frames.

[0136] Identify fine-grained basic units from large-grained data streams, and then complete the demultiplexing of small-grained data streams;

[0137] Restore CBR services from small-granular data streams.

[0138] Example 3

[0139] like Figure 22As shown in the figure, an embodiment of the present invention provides a multi-granularity service processing SPN network structure, including: a master cross-board running a large-granularity time slot cross module, an eastward line board, a westward line board, a small-granularity time slot cross board, and a CBR branch board. The eastward line board and the westward line board between different SPN network structures are interconnected through an east-west link. The master cross-board, eastward line board, westward line board, small-granularity time slot cross board, and CBR branch board of the SPN network structure implement the service processing method based on the above-mentioned metro transmission network large-granularity frame format design method.

[0140] In the embodiments provided by the present invention, it should be understood that the disclosed structure and method can be implemented in other ways. For example, the structure embodiments described above are only illustrative. For example, the division of the units is only a logical function division. In actual implementation, there may be other division methods. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the displayed or discussed couplings or direct couplings or communication connections between each other can be through some interfaces, and the indirect couplings or communication connections of structures or units can be in electrical, mechanical or other forms.

[0141] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0142] In addition, in each embodiment of the present invention, the functional units can be integrated in a processing unit, or each unit can exist physically alone, or two or more units can be integrated in one unit. The above-mentioned integrated units can be implemented in the form of hardware or in the form of software functional units.

[0143] The above are only specific implementation manners of the present invention, enabling those skilled in the art to understand or implement the present invention. Various modifications to these embodiments will be obvious to those skilled in the art. The general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to these embodiments shown herein, but will be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. A method for designing a large-granularity frame format for a metropolitan area transmission network, characterized in that: include: The 5Gbps time slot of the metropolitan area transmission network segment layer is subdivided to construct 1Gbps granularity sub-time slots, wherein the 1Gbps granularity sub-time slots of the metropolitan area transmission network segment layer are realized by adding a time-division multiplexing cycle to the 5Gbps time slots of the metropolitan area transmission network segment layer; the 1Gbps granularity sub-time slot frame format and its overhead format of the 1Gbps granularity sub-time slot are configured; the 1Gbps granularity sub-time slots of the metropolitan area transmission network segment layer are further subdivided into 10Mbps small-granularity slices through a fine-grained metropolitan area transmission network; a kx10Mbps small-granularity frame format adapted to 5Gbps granularity time slots and 1Gbps granularity sub-time slots is constructed; and each level of overhead is used to schedule each fine-grained time slot to realize each fine-grained data transmission.

2. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: In the time-division multiplexing cycle, the 5Gbps time slot x is divided into sub-time slot x.1, sub-time slot x.2, sub-time slot x.3, sub-time slot x.4 and sub-time slot x.5; in each time slot cycle of 5Gbps time slot 1 to time slot 20, 5x1Gbps granularity time slots appear in sequence.

3. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: The overhead of the 1Gbps granularity sub-timeslot frame at the metropolitan area transmission network segment layer is extended by using the reserved bit field in the 5Gbps granularity time slot frame overhead at the metropolitan area transmission network segment layer to realize the information identification of the 1Gbps granularity sub-timeslot at the metropolitan area transmission network segment layer, and only needs to occupy 8 bits in the reserved bit field in total.

4. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: The overhead format of the 1 Gbps granularity sub-timeslot frame includes: timeslot validity indication (C bit), Client Calendar A, Client Calendar B, timeslot adjustment request (CR bit), timeslot adjustment response (CA bit), SE-A, SE-B, Granularity and Sub-slot ID.

5. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: When SE-A ​​is 1, it is combined with the Client Calendar A and Sub-slotID fields to indicate the information of the 1Gbps sub-timeslot configuration table A; when SE-B is 1, it is combined with the Client Calendar B and Sub-slot ID fields to indicate the information of the 1Gbps sub-timeslot configuration table B; when SE-A ​​and SE-B are both 0, the 1Gbps granularity time slot is disabled; the Granularity length is three bits, the default is 001, indicating that the granularity is 1Gbps; Sub-slot ID: indicates the time slot number of the current sub-time slot.

6. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: When the granularity of the large-grained time slot is 5Gbps, the small-grained multiplexing cycle contains a total of 480 sub-segments and 20 fine-grained basic units, and the valid range of the multiframe indication field in the fine-grained basic unit overhead is 0 to 19; when the granularity of the large-grained time slot is 1Gbps, the small-grained multiplexing cycle contains a total of 96 sub-segments and 4 fine-grained basic units, and the valid range of the multiframe indication field in the fine-grained basic unit overhead is 0 to 3.

7. The method for designing a large-granularity frame format for a metropolitan area transmission network according to claim 1, characterized in that: The sub-timeslot configuration related information is distributed in 5 multiframes.

8. A service processing method, based on the large-granularity frame format design method for a metropolitan area transmission network according to any one of claims 1 to 7, characterized in that: include: On the CBR service access node, execute: Step 1: Receive CBR service. Step 2: CBR services are mapped into kx10Mbps small-granular channels through the CBR tributary board. In the small-granular time slot cross-connect board, multiple kx10Mbps small-granular channels are multiplexed into the specified time slots in the fine-granular basic unit 0 to the fine-granular basic unit 3, and form a 1G large-granular customer service flow. Step 3: Map the 1G customer service flow of the fine-grained basic unit 0 to the fine-grained basic unit 3 into the 1G large-grained time slot, and complete the large-grained time slot multiplexing through the large-grained time slot cross module of the 1G time slot, and then send it to the east-west line board of the SPN network; At the intermediate forwarding node of the SPN network, the SPN equipment demultiplexes the 1Gbps large-granularity time slot data corresponding to the 1G large-granularity customer service flow from the interface, and sends the data to the small-granularity time slot cross-connect board, and then demultiplexes the kx10Mbps small-granularity channel data flow in the small-granularity time slot cross-connect board; in the sending direction of the intermediate forwarding node, the small-granularity time slot cross-connect board and the large-granularity time slot cross-connect board complete the step-by-step multiplexing, and send the data to the CBR service egress node; At the CBR service egress node, the reverse process of the CBR service access node is completed.

9. A multi-granularity service processing SPN network structure, characterized in that: include: The main control cross board, east-bound line board, west-bound line board, small-granularity time slot cross board and CBR branch board of the large-granularity time slot cross board running the large-granularity time slot cross board module, the east-bound line board and the west-bound line board between different SPN network structures are interconnected via east-west links, and the main control cross board, east-bound line board, west-bound line board, small-granularity time slot cross board and CBR branch board of the SPN network structure implement the service processing method described in claim 8 based on the large-granularity frame format design method of the metropolitan area transmission network described in any of claims 1-7.

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