An Overview of ITU -T G.709 Monowar Hossain York University

An Overview of ITU -T G.709 Introduction ITU-T G.709 Frame Structure – Optical channel Transport Unit – Optical channel Data Unit – Optical channel Payload unit – Forward Error correction Conclusion Agenda

An Overview of ITU -T G.709 Interface for the Optical transport network (OTN) Concepts borrowed from SONET/SDH – Layered structure – In-service performance monitoring – Protection – Other management function Introduction

An Overview of ITU -T G.709 Added functionality – Management of optical channels in the optical domain – Forward error correction (FEC) to improve error performance and enable longer optical spans Provides standardize method for managing optical wavelengths(channels) end to end Introduction -continued

An Overview of ITU -T G.709 Three line Rates is defined – 2,666, kbs (optical transport unit 1) – 10,709, kbs (optical transport unit 2) – 43,018, kbs (optical transport unit 3) Constant frame rates – kHz ( ms) for OTU1 – kHz ( ms) for OTU3 – kHz(3.035 ms) for OTU3 Introduction -continued

An Overview of ITU -T G.709 Three distinct parts – Overhead area for operation, administration and maintenance function – Pay load area for customer data – Forward error control(FEC) block Frame Structure

An Overview of ITU -T G.709 Size – 4080 * (4 rows) bytes Data is transmitted serially beginning at the top left first row followed by the second row and so on. Frame Structure -continued

An Overview of ITU -T G.709 Size – 4080 * 4 rows Data is transmitted serially beginning at the top left first row followed by the second row and so on. Frame Structure -continued

An Overview of ITU -T G.709 Optical Transport Unit (OTU) Frame Structure -continued

An Overview of ITU -T G.709 OTU overhead – Section Monitoring(SM) – 3 bytes – General communication channel (GCCO) – 2 bytes – Reserved (RS) – 2 bytes Frame Structure -continued

An Overview of ITU -T G.709 Optical channel Data Unit (ODU) overhead – Reside 1-14 columns of rows 2,3 and 4 – Provide tandem connection monitoring(TCM), end to end path supervision – Client signal adaptation via the optical channel payload unit(OPU) Frame Structure -continued

An Overview of ITU -T G.709 Optical channel Payload Unit (OTU) – Contains information to support the adaptation of client signal. – Located in rows 1-4 of columns 15 and 16. – Definitions very depending on the client signal being mapped into the OPU payload. Frame Structure -continued

An Overview of ITU -T G.709 Forward error control(FEC) – 16 FEC blocks of 16 bytes for the row. 64 bytes/frame – Reed-Solomon RS(255,239) code – Uses 16 byte interleaved codecs. – Can correct up to eight symbol errors(correction mood) and detect up to 16 symbol errors in the code (detection mood). – Enables communications to maintain acceptable performance quality in noisy environment. – Provide additional coded data for error checking and error correction Frame Structure -continued

An Overview of ITU -T G.709 Meets two requirements – To cater for the transmission needs of today’s wide range of digital services – To assist network evolution to higher bandwidths and improved network performance A step further toward optical networks Question? Conclusion