WO2007128193A1

WO2007128193A1 - A method for transmitting/receiving the control information in ason and the system thereof

Info

Publication number: WO2007128193A1
Application number: PCT/CN2007/001142
Authority: WO
Inventors: Feng Huang
Original assignee: Alcatel Lucent
Priority date: 2006-04-30
Filing date: 2007-04-09
Publication date: 2007-11-15
Also published as: CN101064565B; CN101064565A

Abstract

A method for transmitting/receiving the control information in Automatic Switched Optical Network (ASON) and the system thereof. The method includes: a1), extracting the control information and encapsulating it; b1), mapping the encapsulated control information into the fix insert byte of the STM-N frame structure; c1), transmitting the STM-N (Synchronous Transport Module) frame. Within the method, the control information includes the signaling, route or link manage information. There is an available 1152Kbit/s bandwidth in a standard container C4 path of STM-N according to the present invention, which expands the bandwidth for the control signals effectively such as the ASON signaling or link resource manage, etc.; further, the control signal is handled with the Ethernet interface, which can achieve the interconnection and interworking between the in-band and other out-band control paths (such as DCN network).

Description

Control information transmission/reception method and system thereof in automatic switched optical network

The present invention relates to optical transmission technology, and more particularly to a control information transmission/reception method and system thereof in ASON (Automatic Switched Optical Network). Background technique

ASON is defined by ITU-T (International Telecommunication Union Telecommunication Standardization Sector) G.8080. The biggest difference from traditional OTN (Optical Transport Network) is that it is a dynamic network, represented by dynamic allocation of bandwidth and network. In the automatic discovery of topology, the realization of this dynamic feature mainly comes from the role of its control plane. The key technologies for constructing the control plane are routing technology, signaling technology, and link management technology.

Routing technology performs routing operations and information discovery of network topologies and resources, passes link state information and calculates the best routing path to another node. Draft ITU-T G.7715/Y.1706 defines the establishment of switching in ASON. Connection SC and soft permanent connection SPC path routing function structure and requirements and ASON routing structure, path selection, routing attributes, abstract information and state transition diagram and other functional components, routing messages are transmitted through DCN (data communication network), G The .7712 specifies a possible implementation of the DCN.

Signaling technology is used to complete the automatic switch connection function, achieve fast end-to-end optical path protection monitoring and recovery, quickly establish, remove and maintain an optical path across the all-optical network, ASON signaling messages can be in-band Transfer, or it can be an out-of-band transfer. Typically, it uses D1-D12 bytes of in-band control signaling based on DCC (Data Communication Path), SDH (Synchronous Digital Transmission System) frame structure SOH (segment overhead).

Link resource management is used to control channel management and maintenance, connectivity verification of transmission links, and fault isolation/location. There are many different link resources in ASON, such as fiber links, wavelength links, various STM layer links and VC (virtual container) layer links in SDH, and so on. These links are called SNP (subnet point) links in ASON. For routing protocol scalability and route diversity, multiple different SNP links can be combined into SNPP (subnet point pool) links. The SNPP link resources are managed by the LRM (Link Resource Manager), that is, the SNP link connection is allocated or released according to the request of the connection controller. But before managing and controlling these SNPP link resources, you first need to find these Link resources and their control entities, this is the automatic discovery technology.

ITU-T G.7714 proposes a general, functional framework description of the automatic discovery technology for transport networks, and discusses mechanisms such as layer adjacency discovery, physical medium adjacency discovery, control entity logical adjacency discovery, and service capability exchange, but no It involves the specific implementation mechanism of the discovery process and detailed attribute parameters. The discovery mechanism based on path trace bytes and ECC (Embedded Communication Channel) in different layers in SDH and OTN specified in ITU-T G.7714.1 is to load discovery messages on these path trace bytes (in The SDH uses the Jx byte or the TTI byte in the OTN network, or the physical layer DCC path corresponding to the ECC is transmitted to the neighboring node.

In the SDH network, the following methods can be used: In the RS (Regeneration Section) layer, the J0 segment trace byte and the regenerative segment DCC (D1-D3) can support the adjacency between the RS segment layer TCP (terminal junction point). Relationship; At the MS (multiplex section) layer, the DCC (D4-D12) of the multiplex section can be used to discover the adjacency relationship between the TCPs of the MS segment layer; in the higher-order VC layer, the high-order channel layer J1 trace byte It can be used to find the adjacency relationship between TCPs of the high-order VC layer; at the low-order VC layer, the low-order channel layer J2 trace bytes can be used to find the adjacency relationship between TCPs of the low-order VC layer.

In the OTN network, the discovery methods that can be used are: In the optical channel transmission unit-k (OTUK) layer, the segment monitoring byte and the general communication channel-O (GCCO) can be used to discover the adjacency between the OTUk layer TCP, in particular The source access point identifier (SAPI) sub-domain in the segment monitoring byte can carry the discovery message; in the optical channel data unit -k (ODUk) layer, the segment monitoring byte and the general communication channel -1 (GCCl It can be used to discover the adjacency relationship between the ODUk layer TCPs, in particular, the source access point identifier (SAPI) sub-domain in the segment monitoring byte can carry the discovery message.

However, the automatic discovery technology based on Jx byte has compatibility problems with the original transmission network. In the original transmission network, Jx bytes may be used for channel monitoring or device connectivity monitoring; on the other hand, Jx The bandwidth of the byte is only 64Kbit/s. In a large-scale ASON network, the message traffic that is automatically discovered is large, which cannot satisfy the high-bandwidth communication, and the convergence speed is slow.

Based on the ECC-based automatic discovery technology, as mentioned above, the D1-D3 bytes in the DCC constitute the regenerative segment.

DCC, D4-D12 bytes constitute a multiplex section DCC, which may be used for control signaling exchange between terminals. Its total 768 kbit/s data communication channel is still unable to control signaling and link resource management. Meet the needs of high-bandwidth communication in large-scale ASON networks and fast convergence.

The invention is to solve the bandwidth problem of control information transmission in ASON, and because of different control letters The problem of compatibility with the original transport network may occur due to the way the information is transmitted. Summary of the invention

According to an aspect of the present invention, a control information transmission method in an ASON, comprising: al), extracting control information and performing encapsulation; M), mapping the encapsulated control information into an STM-N (synchronous transmission module) frame In the structure R (fixed insertion byte) byte; cl), STM-N frame transmission.

In the above transmission method, the control information includes signaling, routing, or link management information.

In the above transmission method, the step a) is performed by using a PPP (Point-to-Point Communication Protocol), LAPS (Link Access Procedure), or GFP (Common Framing Procedure) protocol.

According to another aspect of the present invention, a method for receiving control information in an ASON includes: a2) receiving an STM-N frame; b2) extracting control information mapped in an R byte thereof in the STM-N frame; c2) Decapsulating and restoring the mapped control information.

In the above receiving method, the control information includes signaling, routing, or link management information.

In the above receiving method, the step a2) is performed by using the PPP, LAPS, or GFP protocol.

According to another aspect of the present invention, an automatic optical network system includes a transmitting end and a receiving end, wherein: the transmitting end extracts control information and performs corresponding encapsulation, mapping into R bytes in an STM-N frame structure, and performing STM - N frame transmission; the receiving end receives the STM-N frame, extracts the control information mapped in the R byte, and decapsulates and restores the control information;

In the above automatic optical network system, the receiving end further encapsulates the restored control information into an Ethernet signal to implement interworking with the out-of-band DCN control information.

In the above automatic optical network system, the control information includes signaling, routing, or link management information.

According to the inventive concept, R bytes in the STM-N frame structure are used to transmit control information such as ASON signaling, routing, or link resource management. Since the R bytes are not used in the STM-N frame structure, there is no and The original network compatibility problem, 2x9=18 bytes in a standard container C4 of STM-N, a total of 1152 Kbit/s bandwidth, thus effectively expanding the control information transmission mode and available bandwidth; further, light The network unit uses the Ethernet interface to process the Ethernet processing of the control information, which can effectively realize the interconnection and intercommunication between the in-band and other out-of-band control channels (such as DCN network). DRAWINGS

1 is a structural diagram of an ASON system of the present invention;

2 is a control information transmitting/receiving method in the ASON of the present invention;

3 is a schematic diagram of an ASON control information transmission/reception method of the present invention;

4 is a schematic diagram of R byte insertion in an SDH frame multiplexing process;

Figure 5 shows the STM-N frame structure and its use of R bytes. detailed description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a communication channel exchange composed of R bytes of an STM-N frame in a transmission link 12 formed by an optical interface STM-N between an optical network element 11 and an optical network element 13 in an ASON system according to the present invention. Control information. Here, the control information may be control signaling 121, link management information 122, or routing information 123, such as auto-discovery messages in link management information 122: Hello, Config, ConfigACK, and the like.

Next, the control information transmission/reception method in the ASON system will be further described with reference to FIG. 2: The transmitting end - the optical network network element 11, extracts the control information, and performs corresponding encapsulation and mapping into the standard STM-N frame structure of the SDH. Section, performing SDH data frame transmission;

Step S21, extracting control information and performing encapsulation. The control information may be signaling control information, routing information, and/or resource management information. The encapsulation method can be point-to-PPP, LAPS. or GFP protocol encapsulation. When the LAPS protocol encapsulation mode is adopted: When the upper layer control information comes, a special frame start character is added, and it is judged whether the data has the same identifier. The special characters with the same function, if any, perform special character conversion, add the padding byte, and then perform FCS (frame check) processing and transmit; when using GFP protocol encapsulation mode: This protocol is usually used to encapsulate data information. The GFP frame is composed of a core frame header and a payload area, and encapsulates control information into its payload area and performs load frame check sequence FCS processing and GFP core frame header processing.

Step S22, mapping the control information into R bytes in the STM-N frame structure of the SDH digital transmission module. Generally, in the SDH transmission system, time division byte interleave multiplexing is used. In order to form a regular STM-N frame structure in the multiplexing process, it is necessary to add multiple insertions of R bytes, and R bytes belong to useless bytes. , in the transmission process of the STM-N frame structure, there is no use, here, we use SDH frame The R byte carries the control information after the above encapsulation processing. Figure 3 is a schematic diagram of the R byte insertion of the 34 Mbit/s multiplexed into the STM-N signal. First, the 34 Mbit/s signal is first adapted to the corresponding standard container C3 by the code rate adjustment, and then the corresponding POH is added. (Channel overhead) Packed into VC3, the frame structure at this time is 9x85 (row X column) In order to facilitate the receiver to locate VC3, so that it can be directly detached from the high-speed signal, add 3 words on the VC3 frame. The PTR (pointer) of the section, the information structure at this time is the tributary unit TU3 (the information structure corresponding to the signal of 34 Mbit/s), the frame structure of TU3 is a little broken, and the gap part needs to be added first, usually using the R word Section insertion mode, the information structure after inserting 6 bytes of R bytes is the tributary unit group TUG3, and the three TUG3s are combined into the C4 signal structure by the R byte insertion method, because TUG3 is the information structure of 9 X 86, so 3 The information structure of TUG3 combined by byte interleave multiplexing is 9×258 columns of block frame structure and C4 is 9 X 260 block frame structure, so two columns are added in front of the three TUG3 composite structures ( 2x9) R bytes make it the information structure of C4, the rest of the work is C4 multiplexed STM-N go, i.e. C4 VC4 ^ AU-4 AUG STM-N. Thus, in the 34M digital signal multiplexing process, there are 2x9 R bytes in C4 of STM-N and 6 R bytes in TUG3; if only 2x9 R bytes of C4 are used to carry the control after encapsulation processing For information, the control channel bandwidth using this method will be 1152 Kbit/s.

Step S23: The STM-N optical interface performs electrical-to-optical conversion and transmission on the multiplexed STM-N data frame. Figure 4 shows the STM-1 frame structure and its R byte. The frame structure consists of three parts: SOH, AU-PTR (Management Unit Pointer), PayLoad (Information Payload). The SOH includes RSOH (regeneration section overhead) and MSOH (multiplex section overhead), RSOH consists of the 1st to 3rd lines of the SOH in the STM-N signal, and the MSOH consists of the 5th to 8th lines of the SOH in the STM-N signal. ; AU-PTR is located in the 4th line of the STM-N frame, a total of 9 bytes; In the information payload, the POH is loaded as part of the payload with the information code block in the STM-1 frame, which is responsible for the low-speed signal. Channel performance monitoring, management, and control. As mentioned earlier, the R bytes in the payload carry the encapsulated control information.

The receiving end - the optical network element 13 receives the STM-N data frame of the SDH, extracts the control information mapped in the R byte in the data frame structure, and decapsulates the control information of the restored transmitting end;

Step S23', the STM-N optical interface receives the optical signal and performs optical-to-electrical conversion, and outputs an STM-N data frame;

Step S22', extracting and restoring the control information mapped in the R byte in the SDH data frame structure; in step S21, decapsulating the control information and performing restoration. Packaged by LAPD protocol In the formula, the decapsulation method is: determining a special character, determining the starting point of the frame, receiving the information, performing inverse transformation of the special character, removing the padding byte, restoring the control information, and sending it to the upper layer protocol layer for processing. If it is a GFP encapsulation, the decapsulation method is: determining a frame header by using a GFP cyclic CRC delimitation method, and using a length indication field to indicate a frame length, and extracting control information is sent to an upper layer protocol layer for processing.

It should be noted that, according to the inventive concept, if the transmitting end-optical network element 11 carries different control information by using R bytes in the data frame structure, for example, carrying control signaling and automatic discovery message simultaneously, the above step S21 ' The carried control information needs to be further differentiated and sent to the corresponding upper layer protocol layer for processing. Since the control information is carried by IP, usually we can distinguish the type of control information carried by the protocol field or TCP/UDP port number of the IP layer, that is, which are control signaling, which are automatic discovery messages, and send Processed to the corresponding upper protocol layer.

In order to achieve interworking with other out-of-band control information, the upper layer protocol layer can be encapsulated into an Ethernet signal in one step to implement interworking with the Ethernet out-of-band DCN signaling channel. Meet different control channel transmission compatibility.

FIG. 5 is a schematic diagram of an optical network unit implementation structure for simply transmitting/receiving control information thereof, including an ASON control unit 51, a link resource management unit 52, a routing unit 53, an Ethernet interface unit 54, and a package processing unit. 55. A frame multiplexing/demultiplexing unit 56, wherein:

The ASON control unit 51, the link resource management unit 22, and the routing unit 53 will respectively generate respective control signals (such as control signaling, automatic discovery messages, etc., routing messages) for the optical network unit, and select different control channels. Transmission method (including selection of in-band or out-of-band transmission mode, or selection of different in-band transmission modes); and receiving control signals from other optical network units through different control channel transmission methods, and corresponding processing.

The encapsulation processing unit 24, for the transmitting end, encapsulates the control information from the upper layer, and the control information may be from the ASON control unit 51, the link resource management unit 22, or the routing unit 53 and any combination thereof; The processing may be performed by using LAPS protocol encapsulation or GFP protocol, etc.; for the receiving end, it receives control information from other optical network units for reverse decapsulation processing and sends it to the corresponding ASON control unit 51, link resource management Unit 22 or routing unit 53 performs the processing.

It should be noted that, if the receiving control channel carries different control information, for example, carrying control signaling and automatic discovery messages, the encapsulation processing unit 24 needs to enter one after decapsulation processing. Steps distinguish the control information and send it to the corresponding ASON control unit 51, link resource management unit 22 or routing unit 53 for processing. The above control information is carried by IP, usually through the protocol layer of the IP layer or the TCP/UDP port number. To distinguish between the types of control information carried, that is, which are control signaling, which are automatic discovery messages, and which are routing information.

The SDH frame multiplexing/demultiplexing unit 56, at the transmitting end, maps the above encapsulated control information into R bytes in the STM-N frame structure; at the receiving end, it extracts the STM-N frame structure Control information carried in the R byte.

In order to achieve interworking with other out-of-band control information, the optical network unit further includes an Ethernet interface unit 54, which will come from the ASON control unit 51, the link resource management unit 52, and/or the routing unit.

The control information of 53 is encapsulated into an Ethernet signal to implement interworking of the DCN signaling channels outside the Ethernet band.

While the foregoing is a description of the embodiments of the present invention, it is not intended to limit the scope of the invention, and various modifications may be made to the embodiments without departing from the scope and spirit of the invention. Such modifications are all within the scope of the invention.

Claims

Rights request

1. A method for controlling information transmission in an automatic optical network system, comprising -al), extracting control information and encapsulating;

M), mapping the encapsulated control information into an STM-N (synchronous transfer module) frame structure

R byte (fixed insertion byte);

Cl), perform STM-N frame transmission.

2. The method of claim 1 wherein the control information comprises signaling, routing or link management information.

3. The method of claim 1 or 2, wherein said step a) said using said package

PPP (Point-to-Point Communication Protocol), LAPS (Link Access Procedure Protocol), or GFP (Common Framing Procedure) protocol mode.

4. A method for receiving control information in an automatic optical network system, comprising:

A2), receiving an STM-N frame;

B2) extracting control information mapped in its R byte in the STM-N frame;

), decapsulating and restoring the mapped control information.

5. The method of claim 4 wherein the control information comprises signaling, routing or link management information.

The method according to claim 4 or 5, characterized in that said step a2) said decapsulating is reverse processed using PPP, LAPS, or GFP protocol.

7. An automatic optical network system, comprising: a transmitting end and a receiving end, wherein:

The transmitting end extracts control information and performs corresponding encapsulation and mapping into R bytes in the STM-N frame structure to perform STM-N frame transmission;

Receiving, by the receiving end, an STM-N frame, extracting control information mapped in the R byte, and decapsulating the control information;

8. The automatic optical network system according to claim 7, wherein the receiving end further encapsulates the restored control information into an Ethernet signal to implement interworking with the out-of-band DCN (data communication network) control information.

The automatic optical network system according to claim 7 or 8, wherein the transmitting end and the connecting end are connected The receiving control information includes signaling, routing or link management information.