1、 International Telecommunication Union ITU-T G.7044/Y.1347TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU (10/2011) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Data over Transport Generic aspects General SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE, INTERNET PROTOCOL ASPECT
2、S AND NEXT-GENERATION NETWORKS Internet protocol aspects Transport Hitless adjustment of ODUflex(GFP) Recommendation ITU-T G.7044/Y.1347 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHA
3、RACTERISTICS COMMON TO ALL ANALOGUE CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH
4、 METALLIC LINES G.400G.449 COORDINATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 MULTIMEDIA QUALITY OF SERVI
5、CE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.1999 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 General G.7000G.7099Transport network control aspects G.7700G.7799 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999
6、 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.7044/Y.1347 (10/2011) i Recommendation ITU-T G.7044/Y.1347 Hitless adjustment of ODUflex(GFP) Summary Recommendation ITU-T G.7044/Y.1347 defines hitless adjustment of ODUflex(GFP) (HAO), which provides a control me
7、chanism to hitlessly increase or decrease the bandwidth of an ODUflex(GFP) connection in an optical transport network (OTN). History Edition Recommendation Approval Study Group 1.0 ITU-T G.7044/Y.1347 2011-10-29 15 ii Rec. ITU-T G.7044/Y.1347 (10/2011) FOREWORD The International Telecommunication Un
8、ion (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommunication Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions
9、and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembly (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on t
10、hese topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the ex
11、pression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applic
12、ability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory language such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with th
13、e Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Recommendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicabi
14、lity of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement thi
15、s Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2012 All rights reserved. No part of this publication may be reproduced, by any means what
16、soever, without the prior written permission of ITU. Rec. ITU-T G.7044/Y.1347 (10/2011) iii Table of Contents Page 1 Scope 1 2 References. 1 3 Definitions 1 3.1 Terms defined elsewhere 1 3.2 Terms defined in this Recommendation . 1 4 Abbreviations and acronyms 2 5 Conventions 3 6 Introduction 3 6.1
17、Methodology . 3 6.2 Control overhead 4 6.3 Resize protocol . 8 6.4 Management and/or control plane interaction 10 7 Resize procedure . 10 7.1 Bandwidth Increase 11 7.2 Bandwidth Decrease . 17 8 Maintenance signals 26 Annex A HAO SDL diagrams 27 A.1 Hitless adjustment of ODUflex(GFP) (HAO) process ov
18、erview . 27 A.2 HAO SDL diagrams . 29 Appendix I BWR rate change stability measurement . 36 Rec. ITU-T G.7044/Y.1347 (10/2011) 1 Recommendation ITU-T G.7044/Y.1347 Hitless adjustment of ODUflex(GFP) 1 Scope This Recommendation specifies hitless adjustment of ODUflex(GFP) (HAO) that should be used to
19、 hitlessly increase or decrease the bandwidth of an ODUflex(GFP) that is transported in an optical transport network (OTN). The Recommendation is based on the OTN signals specified in ITU-T G.709. 2 References The following ITU-T Recommendations and other references contain provisions which, through
20、 reference in this text, constitute provisions of this Recommendation. At the time of publication, the editions indicated were valid. All Recommendations and other references are subject to revision; users of this Recommendation are therefore encouraged to investigate the possibility of applying the
21、 most recent edition of the Recommendations and other references listed below. A list of the currently valid ITU-T Recommendations is regularly published. The reference to a document within this Recommendation does not give it, as a stand-alone document, the status of a Recommendation. ITU-T G.709 R
22、ecommendation ITU-T G.709 (2009), Interfaces for the Optical Transport Network (OTN). ITU-T G.798 Recommendation ITU-T G.798 (2010), Characteristics of optical transport network hierarchy equipment functional blocks. ITU-T G.870 ITU-T Recommendation G.870 (2012), Terms and definitions for optical tr
23、ansport networks (OTN). ITU-T Z.100 Recommendation ITU-T Z.100 (2007), Specification and Description Language (SDL). 3 Definitions 3.1 Terms defined elsewhere This Recommendation uses the following terms defined elsewhere: 3.1.1 Terms defined in ITU-T G.870: GMP normal mode GMP special mode OPUk mul
24、tiframe Resize Multiframe (RMF) 3.2 Terms defined in this Recommendation None. 2 Rec. ITU-T G.7044/Y.1347 (10/2011) 4 Abbreviations and acronyms This Recommendation uses the following abbreviations and acronyms: ACK Acknowledge BG BWR Generator BR BWR Receiver BRG BWR Relay Generator BRR BWR Relay R
25、eceiver BWR Bandwidth Resize CC Consistent Configuration Cmnumber of m-bit client data entities Cnnumber of n-bit client data entities CnDdifference between Cnand (m/n Cm) CRC Cyclic Redundancy Check CTRL Control CV Consistent Verification EMF Equipment Management Function FRR Flex RCOH Receiver GMP
26、 Generic Mapping Procedure HAO Hitless Adjustment of ODUflex HO High Order LC Link Connection LCAS Link Capacity Adjustment Scheme LCR Link Connection Resize LG LCR Generator LO Low Order LR LCR Receiver MC Matrix Connection MSI Multiplex Structure Identifier NACK Negative Acknowledgement NCS Networ
27、k Connectivity Status NE Network Element ODU Optical channel Data Unit ODUk Optical channel Data Unit-k OH Overhead OPU Optical channel Payload Unit OPUk Optical channel Payload Unit-k OTN Optical Transport Network Rec. ITU-T G.7044/Y.1347 (10/2011) 3 PSI Payload Structure Identifier RCOH Resize Con
28、trol Overhead RES Reserved for future international standardization RG RCOH Generator RMF Resize Multiframe RP Resizing Protocol RR RCOH Receiver SDL Specification and Description Language TPID Tributary Port ID TS Tributary Slot TSCC Tributary Slot Connectivity Check TSGS Tributary Slot Group Statu
29、s TSOH Tributary Slot Overhead VCAT Virtual Concatenation xI CI or MI or AI 5 Conventions Transmission order: The order of transmission of information in all the diagrams in this Recommendation is first from left to right and then from top to bottom. Within each byte the most significant bit is tran
30、smitted first. The most significant bit (bit 1) is illustrated at the left in all the diagrams. Value of reserved bit(s): The value of an overhead bit, which is reserved or reserved for future international standardization, shall be set to “0“. 6 Introduction Hitless adjustment of ODUflex(GFP) (HAO)
31、 is a resizing mechanism within the optical transport network (OTN) that allows it to support an increase or decrease of ODUflex(GFP) client data rate across its entire end-to-end path. In many ways, it is similar to the virtual concatenation/link capacity adjustment scheme (VCAT/LCAS). It should be
32、 noted that unlike the VCAT, where each component of the end-to-end container is an optical channel data unit-k (ODUk) which can be connected through the OTN independently from all other ODUk components of the same container, an ODUflex signal is carried over a single end-to-end path over a group of
33、 tributary slots on each high order-optical channel payload unit-k (HO OPUk) of the path. ODUflex(GFP) resizing has the advantage over VCAT and LCAS that since all the TSs that carry the ODUflex(GFP) client signal follow the same path from the source of the OTN to the sink, it is not necessary to co
34、mpensate for the individual TSs having different timing delays. In addition, the ODUflex is a single managed entity rather than containing separate managed entities for each member of a VCAT group. It should also be noted that unlike VCAT/LCAS resizing, which requires participation by only the borde
35、r NEs, HAO requires the participation of each and every NE along the ODUflex(GFP) path. 6.1 Methodology HAO functionality in the ODUflex(GFP) to packet source and sink adaptation functions and in HO ODUk to LO ODUflex adaptation source and sink functions provides a control mechanism to hitlessly inc
36、rease or decrease the capacity of an ODUflex(GFP) connection to meet the bandwidth 4 Rec. ITU-T G.7044/Y.1347 (10/2011) needs of the application. To accomplish hitless bandwidth adjustment of an ODUflex(GFP) connection, all nodes in the connection must support the HAO protocol, otherwise, the connec
37、tion requires tear down and rebuilding. The bit rate adjustment of the ODUflex(GFP) occurs simultaneously among all the nodes in the ODUflex(GFP) connection to prevent buffer overflow or underflow. A resizable ODUflex(GFP) occupies the same number of tributary slots on every link of the server. In c
38、ases of bandwidth adjustment (i.e., increase or decrease), the same number of tributary slots (at least one TS) on each link traversed by the resized ODUflex(GFP) must be involved. Resizable ODUflex(GFP) bit rates are specified in Table 7-8 of ITU-T G.709, illustrated in Figure 6-1, where n is the n
39、umber of tributary slots that are assigned to the resizable ODUflex(GFP). The HAO application supports ODUflex(GFP) bandwidth increase or decrease from current n range to a different n range if the link of the server permits. G.7044-Y.1347(11)_F6-1ODUflex(GFP)n ODU2.ts(n = 1 to 8)ODUflex(GFP)n ODU3.
40、ts(n = 9 to 32)ODUflex(GFP)n ODU4.ts(n = 33 to 80)IncreaseIncreaseIncreaseDecreaseDecreaseDecreaseODU2.ts ODU3.ts ODU4.ts0 1 8 9 32 33 7980ODUflex(GFP)bit rateFigure 6-1 Recommended ODUflex(GFP) bit rate in HAO capability The modification of the ODUflex(GFP) link and matrix connection configurations
41、 are the responsibility of the network management or control plane. 6.2 Control overhead Synchronization of changes in the capacity of an ODUflex(GFP) connection shall be achieved by resize control overhead (RCOH). The RCOH consists of fields dedicated to a specific function. Changes are sent in adv
42、ance so that the receiver can switch to the new configuration as soon as it arrives. The RCOH is carried in the HO OPUk tributary slot overhead (TSOH) and the OPUflex overhead as shown in Figure 6-2. These RCOH (RCOH1, RCOH2 and RCOH3) bytes are located in column 15, row 1, 2 and 3. The HO OPUk RCOH
43、 is carried in the tributary slot which is to be added or to be removed. If multiple tributary slots are involved in one resize operation, the protocol is carried in all of these TS RCOHs to be added or to be removed. The RCOHs of these TSs involved in the same resize operation are always the same a
44、nd transmitted identically. NOTE This Recommendation only specifies the RCOH for HAO protocol. For use of these bytes for other applications, refer to ITU-T G.709. The RCOH is divided into two parts: link connection resize (LCR) protocol overhead and bandwidth resize (BWR) protocol overhead. The LCR
45、 protocol overhead includes the control (CTRL) field, tributary port ID (TPID) field and tributary slot group status (TSGS) bit. The BWR protocol overhead includes the network connectivity status (NCS) bit, tributary slot connectivity check (TSCC) bit, resizing protocol indicator (RP) bit and bandwi
46、dth resize indicator (BWR_IND) bit. Rec. ITU-T G.7044/Y.1347 (10/2011) 5 The LCR protocol bits, the RP bit and the TSCC bit in the BWR protocol are carried in HO OPUk (k = 2, 3, 4) tributary slot overhead, and the NCS bit and BWR_IND bit in the BWR protocol are carried in the OPUflex overhead. G.704
47、4-Y.1347(11)_F6-2ColumnColumnRowRow1515112233441122331122334455667788BWR_INDRPBWR_INDTSCCRESRESRESRESRESRESRESTPIDRESRESCRC-5NCSRES TSGS CTRL TPIDCRC-3CRC-3RCOH1RCOH1RCOH2RCOH2RCOH3RCOH3PSIPSIOPUflex OHHO OPUk OHOPUflex RCOHHO OPUk RCOHFigure 6-2 RCOH format This RCOH supports ODUflex(GFP) LCR contr
48、ol fields and ODUflex(GFP) BWR control fields. The default value of this RCOH is all-0s. 6.2.1 Control (CTRL) field The control field is used to transfer LCR protocol status information from source to sink. It shall be used to provide the operation indication of the individual tributary slot that be
49、longs to a specified ODUflex(GFP) connection. The CTRL field is carried in the LCR protocol overhead in HO OPUk (k = 2, 3, 4) overhead row 2, column 15, bits 5 and 6. Table 6-1 HAO CTRL words Value Command Remarks 00 IDLE Indication that the node has completed LCR and there is no new LCR operation. IDLE may also be transmitted for a short time at operation start before transmission of the ADD/REMOVE command. 01 ADD Indication that the tributary slot is to be added to the ODUflex(GFP) connection 10 REMOVE Indic
