CN100370778C - Method for Transporting Service in Resilient Packet Ring Network - Google Patents

Abstract

The invention discloses a method for transmitting services in an elastic packet ring network, comprising: using the general framing protocol payload frame header extension field to carry the elastic packet ring frame header information; setting the elastic packet ring network according to the frame format of the general frame processing protocol Management frame: manage the transmission service of the elastic packet ring network through the elastic packet ring network management frame. The invention can improve user service data encapsulation efficiency and physical layer bandwidth utilization rate, simplify system design and reduce cost.

Description

Method for Transporting Service in Resilient Packet Ring Network

technical field

The invention relates to the field of communication technology, in particular to a method for transmitting services in an elastic packet ring network.

Background technique

At present, with the development of the Internet, the data traffic is growing explosively, which provides new requirements for the development of the metropolitan area network that acts as a link between the enterprise network and the wide area network. Resilient packet data ring RPR technology is a new network architecture and technology designed to meet the requirements of packet-based metropolitan area network; it is a ring network composed of packet switching nodes. Its topology is shown in Figure 1. The adjacent Nodes are connected by a pair of optical fibers; its network topology is based on two rings transmitting in opposite directions.

RPR (Resilient Packet Ring) technology is a MAC (Media Access Control Layer) layer protocol that optimizes data service transmission on a ring structure, and can adapt to various physical layers, such as SDH (Synchronous Transmission Hierarchy), Ethernet, DWDM ( Dense wavelength division multiplexing), which can effectively transmit data of various business types such as voice and image. It combines the economical, flexible, and scalable features of Ethernet technology, and absorbs the advantages of SDH ring network's 50ms fast protection, and has network topology automatic discovery, ring bandwidth sharing, fair allocation, and strict COS (business classification) and other functions.

In the new generation of SDH/SONET (Synchronous Digital Hierarchy/Synchronous Optical Network) products, the RPR ring network technology has been embedded in the SDH equipment, and the RPR over SDH (SDH bears RPR) networking method can be used to make full use of the existing resources of the transmission network, and enhance the carrying capacity of the transmission network for data services. RPR over SDH enables operators to provide high-speed data services while retaining support for traditional circuit-based voice services. RPR over SDH adopts the hierarchical structure shown in Figure 2. Correspondingly, the user's service packet processing flow is shown in Figure 3:

Step1: Customer's data package;

Step2: Add the customer's data packet to the RPR Head to facilitate the protocol processing of the RPR layer. The user's data is regarded as the payload in the RPR to form the RPR frame format.

Step3: The package that encapsulates the RPR data header is then encapsulated with the GFP Head to form a GFP frame and mapped to the SDH frame format;

Step4: SDH is transmitted in optical fiber or copper cable.

The encapsulated GFP frame format includes: the core header in the GFP frame header, the payload frame header, and the GFP payload area includes: the PRP frame header, user payload data, and FCS (Frame check sequence).

It can be seen from the figure that the user's data packet needs to be encapsulated by adding RPR header and GFP header, and then transmitted by the physical medium. Such two-layer encapsulation will reduce the transmission efficiency; at the same time, it involves multi-layer processing, including encapsulation and extraction of different protocols, resulting in complex structural design and increased product development costs.

In order to ensure normal transmission of user services on the RPR ring network, various signaling messages need to be transmitted between nodes. In the prior art, the RPR protocol layer and the GFP protocol layer are processed separately and independently, and are designed to be processed by different modules without any relationship with each other, which makes the system design complicated, and the transmission and processing efficiency is relatively low .

Contents of the invention

The purpose of the present invention is to provide a method for transmission in a resilient packet ring network, to solve the problems of complex processing and low transmission efficiency in the RPR ring network in the business layer transmission signaling mode in the prior art, and to ensure the safe and reliable transmission of RPR signaling while simplifying product design.

The purpose of the present invention is achieved through the following technical solutions:

A method for transmitting services over a resilient packet ring network, comprising:

A. Utilizing the general framing protocol payload frame header extension field to carry the RPR frame header information;

B. Arbitrarily select a value in the domain reservation situation of the general framing protocol frame to be defined as the elastic packet ring network management frame;

C. Manage the transmission service of the RPR network through the RPR network management frame.

The RPR network management frames include: management control frames, fair frames, and idle frames.

The domain is a PTI domain or a UPI domain.

Described step C comprises:

C1. Encapsulate the service data by using the general framing protocol;

C2. Inserting the elastic packet ring network management frame according to a predetermined method;

C3. Transmitting information of different nodes on the RPR network through the RPR network management frame.

The specific booking methods are as follows:

Inserting the elastic packet ring network management frame at regular intervals or inserting the elastic packet ring network management frame when it is necessary to detect the states of the different nodes.

Said step C3 comprises:

transmitting the status and control information of the different nodes through the management control frame;

transmitting traffic information between the different nodes through the fair frame;

The transmission rate between the different nodes is adjusted through the idle frame.

As can be seen from the technical solution provided by the present invention above, the present invention realizes the transfer of signaling protocol through the GFP encapsulation layer in the RPR ring network, encapsulates the PRR header in the net load frame header extension field area of GFP, and makes full use of the GFP The header extension area improves the encapsulation efficiency, simplifies the encapsulation process and multi-layer complex processing of signaling transmission, reduces the occupation of physical layer bandwidth, and makes the signaling transmission simple and reliable; due to the reduction of encapsulation layers, the system Design complexity, which in turn can reduce equipment cost. The present invention also utilizes the formed GFP transfer channel to realize RPR ring network protection.

Description of drawings

Figure 1 is a schematic diagram of the RPR ring network structure;

Fig. 2 is a network hierarchy diagram of prior art SDH/SONET carrying RPR;

Fig. 3 is prior art RPR over SDH/SONET user business packet processing flowchart;

Fig. 4 is a schematic diagram of the frame structure of GFP;

Figure 5 is a schematic diagram of the structure of the GFP payload head;

Fig. 6 is the encapsulation format when utilizing the GFP extension header to transmit the signaling of the upper layer business or the agreement in the method of the present invention;

Fig. 7 is the GFP frame format to user service data encapsulation process and encapsulation in the method of the present invention;

Fig. 8 is GFP client frame format;

Fig. 9 is the encapsulation format when utilizing the GFP client management frame to transmit the signaling or the protocol of the upper layer business in the method of the present invention;

Fig. 10 is the encapsulation format when the signaling or protocol of the upper layer service is transmitted by defining a new type frame in the method of the present invention;

Fig. 11 is a flowchart of the method of the present invention;

Fig. 12 is a schematic diagram of implementing 1:1 protection by inserting a management control frame in the method of the present invention.

Detailed ways

The core of the present invention is to use the GPF (General Framing Protocol) layer to carry the signaling protocol in the RPR ring network, and encapsulate the PRR header in the payload frame header extension area of GFP, and realize each node through the channel formed by the GFP encapsulation layer. Communication between signaling and business data.

In order to enable those skilled in the art to better understand the solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments.

At first the GFP frame structure used in the present invention is made a simple explanation:

The GFP frame format is defined in detail in the G.7041 standard. The GFP frame structure is shown in Figure 4, including two parts: the GFP frame header (Core Header) and the GFP payload area (GFP Payload Area). Among them, the GFP frame header includes: frame length identification (PLI) and frame header error check (Core HEC). PLI is 2 bytes, which indicates the length of the payload of the frame, and the frame header error check is also 2 bytes. It uses the CRC-16 error detection method to provide protection for the frame header; the GFP payload area includes: payload header (Payload Header), payload information domain (Payload Information) and payload frame check sequence (Payload FCS) three parts.

According to the above GFP protocol definition, the present invention utilizes the GFP layer to realize the encapsulation of upper-layer user signaling and protocols, specifically including:

(1) Use the extended section of the GFP frame to carry the RPR encapsulation header

The structure of the GFP Payload Header (Payload Header) is shown in Figure 5, including: 2-byte type field (Payload Type), 2-byte type field check (Type HEC), and 0-60 bytes of extended header information field (including the 2-byte extended header verification field).

It can be seen that the extension header in the payload header can be used to carry the RPR header, and the RPR frame header information can be directly inserted into this area to realize the encapsulation of the RPR layer. The header includes but is not limited to the following information: source node address, destination node address, RPR internal and external Ring ID, TTL (Time to live), control information, protocol type and other information. Of course, the extension header in the payload header can also be used to transmit the signaling or protocol of the upper layer service, and the user information is directly inserted into this area to complete the transmission of the information protocol. The signaling encapsulation format is shown in Figure 6.

For user service data encapsulation, the RPR encapsulation and GFP encapsulation processes in the prior art are combined, which simplifies the encapsulation process and improves protocol encapsulation efficiency compared with the prior art. The encapsulation process of user service data and the format of the encapsulated GFP frame are shown in FIG. 7 .

Step1: Customer's data package;

Step2: Encapsulate the customer's data packet into the GFP header, carry the RPR protocol in the GFP frame header, form a GFP frame, and map it to the SDH frame format;

Step3: SDH is transmitted in optical fiber or copper cable.

The encapsulated GFP frame format includes: GFP frame header, payload frame header, payload extension frame header including RPR frame header, GFP payload area includes: user payload data, and also includes frame check sequence FCS.

(2) Use the GFP client management frame to define the RPR ring network management frame

Frames defined according to the GFP format are divided into two categories:

a. GFP client frame: complete the encapsulation of client side information, including client data frame (encapsulation of client data information) and client management frame (encapsulation of some client management information);

b. GFP control frame: defines GFP connection management, currently only defines the Idle (idle) frame of GFP.

According to the definition of the GFP protocol, the PLI field of the GFP core frame header indicates the payload length indication. When PLI=0~3, it is represented as a GFP control frame, which defines GFP connection management. According to the current protocol, the control frame is only defined as a GFP Idle frame when PLI=0, which is used for rate adaptation in the data mapping process. PLI=1~3 is reserved and not defined at present. When PLI=4～65535, represent as GFP client frame, as shown in Figure 8, complete the encapsulation of client side information, comprise client data frame (encapsulate client data information) and client management frame (encapsulate some clients' management information frames).

PTI (Payload type Identifier, payload type indication), used to indicate the type of user data transmitted in GFP encapsulation, is currently defined in ITU-t G.7041 as shown in Table 1 below:

Table 1:

  Payload type indication PTI type bits <15:13> usage 000 Client Data 100 ClientManagement (client management frame) Others Reserved

When the frame type identifier PTI=100, it means the customer management frame, which is used for client management information transmission. At present, only two kinds of UPI=00000001 are defined in the UPI (User payload Identifier, user payload identifier) field as the client signal loss (Loss of Client Signal); UPI＝00000010 is character synchronization loss (Loss of Character Synchronization); UPI＝00000000, 00000011～11111111 are undefined.

It can be seen that the undefined customer management frame when UPI=00000000, 00000011~11111111 can be used to transmit the signaling or protocol of the upper layer service, and the user information can be directly inserted into this area to complete the transmission of the information protocol. The signaling encapsulation format is shown in Figure 9 Show.

For example, by defining the value of UPI to distinguish management control frames, fair frames, and idle frames of the RPR protocol:

When UPI=00000011, it is defined as RPR management control frame;

When UPI=00000100, it is defined as RPR fair frame;

In this way, the management frame can be quickly extracted through hardware logic for subsequent corresponding processing, thereby improving processing efficiency.

(3) Utilize the new type frame to define the RPR ring network management frame

It can be seen from Table 1 that PTI=000 and PTI=100 are used to define customer data frame and customer management frame respectively, and the PTI field contains 3 bits, which can represent 8 types of frames at most, so the currently unused type PTI= 001-011 and PTI=101-111 can all be used to define transmission signaling, and the signaling encapsulation format is shown in FIG. 10 .

For example, by defining different PTI values to distinguish whether it is a service frame or a management control frame:

When PTI=001, it is defined as a management control frame;

When UPI=101, it is defined as a fair frame;

In this way, the management frame can be quickly extracted through hardware logic for subsequent corresponding processing, thereby improving processing efficiency.

The GPF frame is used to transmit different signaling of the user through the above three methods, which can be selected according to the actual situation.

Fig. 11 is a flowchart of the method of the present invention, comprising the following steps:

Step S1: use the GFP protocol payload frame header field to carry the RPR frame header information;

Step S2: Set the RPR management frame according to the GFP frame format, including: management control frame, fair frame, and idle frame. The specific definition is as follows:

Utilize arbitrarily select a value in the reserved situation of user payload identification UPI of general framing protocol customer management frame to be defined as described RPR network management frame; or

A value is arbitrarily selected from the reservation status of the PTI indicated by the payload type of the general framing protocol frame and defined as the RPR management frame.

The above two definition methods have been described in detail above, and will not be repeated here.

Step S3: use the GFP protocol to encapsulate the service data. During the protocol encapsulation process, the RPR protocol is inserted into the GFP protocol payload frame header field, and the encapsulation of the GFP protocol and the RPR protocol is completed at one time.

Step S4: Insert the RPR management frame in a predetermined manner. According to actual needs, the RPR management frame can be inserted at regular intervals or the RPR management frame can be inserted when the status of different nodes on the RPR ring network needs to be detected. The management of the RPR ring network is implemented through these management frames.

Step S5: Transmit the information of different nodes on the RPR ring network through the RPR management frame, so as to realize the management of user services and the RPR ring network.

For example:

transmitting the status and control information of the different nodes through the management control frame;

transmitting traffic information between the different nodes through the fair frame;

The transmission rate between the different nodes is adjusted through the idle frame.

As long as the protocol channel between two network elements can be provided, different network elements can use the channel service flow information, network topology information, congestion information between stations, etc., so that each node can extract packets through hardware and send them to the upper layer software for processing. In this way, the management of the RPR ring network can be implemented.

Fig. 12 shows the process of realizing 1:1 protection of the RPR ring network through the management frame in the method of the present invention, that is, the link status between the two network elements is transmitted through the GFP signaling channel between the two network elements, and the service is realized. choose. The implementation process is as follows:

1. Node A double-transmits the service, and transmits the same service on the working path and the protection path at the same time;

2. The destination node B selects and receives services, and selects the end with a good signal;

3. To facilitate business judgment at point B, a status confirmation message can be sent periodically at point A.

For example, when PTI=010, it is defined as a 1:1 management control frame;

In this way, the management and control frame of PTI=010 between nodes A and B in Figure 12 can be used to transmit the link state information between the two nodes, and the hardware logic can quickly extract the management and control frame by identifying the frame of PTI=010 to provide Migrate the protocol state machine for the software, thus realizing 1:1 protection based on the packet level.

The specific business implementation process is as follows:

1. A node only sends business data to B node through the working path;

2. In order to ensure that Node B can monitor the quality of the working path in real time, Node A regularly sends a management control frame with PTI=010 from the working path to Node B;

3. In order to ensure that Node B can monitor whether the protection path is good or bad in real time, Node A regularly sends a management control frame with PTI=010 from the protection path to Node B;

4. The node B monitors the management control frame of PTI=010 received by the working path and the protection path respectively. If it can be received regularly, it means that the link state is normal.

5. If the working path from A to B fails (such as a fiber failure), node B will not be able to receive regular management control frames on the working path, which can trigger the upper layer software to renegotiate the business path between nodes A and B;

6. After the negotiation between nodes A and B is completed, node A sends the service to B from the protection path, and node B can normally receive the service on the protection path, thereby realizing service protection.

While the invention has been described by way of example, those skilled in the art will appreciate that there are many variations and changes to the invention without departing from the spirit of the invention, and it is intended that the appended claims cover such variations and changes without departing from the spirit of the invention.

Claims (6)

1. A method for transmitting services over a resilient packet ring network, characterized in that it comprises: A. Utilizing the general framing protocol payload frame header extension field to carry the RPR frame header information; B. Arbitrarily select a value in the domain reservation situation of the general framing protocol frame to be defined as the elastic packet ring network management frame; C. Manage the transmission service of the RPR network through the RPR network management frame. 2 . The method for transmitting services in an RPR network according to claim 1 , wherein the RPR network management frames include: management control frames, fair frames, and idle frames. 3 . 3. The method for transmitting services over an RPR network according to claim 1 or 2, wherein the domain is a PTI domain or a UPI domain. 4. The method for transmitting services over an RPR network according to claim 2, wherein said step C comprises: C1. Encapsulate the service data by using the general framing protocol; C2. Inserting the elastic packet ring network management frame according to a predetermined method; C3. Transmitting information of different nodes on the RPR network through the RPR network management frame. 5. The method for transmitting services over an RPR network according to claim 4, wherein the predetermined method is specifically: Inserting the elastic packet ring network management frame at regular intervals or inserting the elastic packet ring network management frame when it is necessary to detect the states of the different nodes. 6. The method according to claim 4, wherein said step C3 comprises: transmitting the status and control information of the different nodes through the management control frame; transmitting traffic information between the different nodes through the fair frame; The transmission rate between the different nodes is adjusted through the idle frame.

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