ITU-T The ITU Telecommunication Standardization Sector (ITU-T) is one of the three sectors (divisions or units) of the International Telecommunication Union (ITU). It is responsible for coordinating standards for telecommunications and Information Comm ...

Recommendation G.709 ''Interfaces for the Optical Transport Network (OTN)'' describes a means of communicating data over an optical network. It is a standardized method for transparent transport of services over optical wavelengths in

DWDM In fiber-optic communications, wavelength-division multiplexing (WDM) is a technology which multiplexes a number of optical carrier signals onto a single optical fiber by using different wavelengths (i.e., colors) of laser light. This techni ...

systems. It is also known as Optical Transport Hierarchy (OTH) standard. The first edition of this protocol was approved in 2001. The G.709 OTUk signal is positioned as a server layer signal for various client signals, e.g. SDH/SONET, ATM, IP,

Ethernet Ethernet () is a family of wired computer networking technologies commonly used in local area networks (LAN), metropolitan area networks (MAN) and wide area networks (WAN). It was commercially introduced in 1980 and first standardized in 1 ...

, Fibre Channel and OTN ODUk (where k=0, 1, 2, 2e, 3, 3e2, 4 or flex).The letter ''k'' represents the ODUk data rate as follows: :0 = ~1.24 Gbit/s :1 = ~2.50 Gbit/s :2 = ~10.04 Gbit/s :2e = ~10.40 Gbit/s :3 = ~40.32 Gbit/s :3e2 = 41.79 Gbit/s :4 = ~104.79 Gbit/s :flex = a multiple of ~1.24 Gbit/s Work on support for

InfiniBand InfiniBand (IB) is a computer networking communications standard used in high-performance computing that features very high throughput and very low latency. It is used for data interconnect both among and within computers. InfiniBand is also use ...

and

Common Public Radio Interface The Common Public Radio Interface (CPRI) standard defines an interface between Radio Equipment Control (REC) and Radio Equipment (RE). Oftentimes, CPRI links are used to carry data between cell sites and base stations. The purpose of CPRI is to a ...

client signals is currently in progress. The frame structure defined in G.709 is constructed of 4 areas: # OPUk is the area in which payload is mapped. # ODUk contains the OPUk with additional overhead bytes (e.g. TTI,

BIP8 BIP-8 (alternatively, BIP8) is an abbreviation for ''bit-interleaved parity 8''. BIP-8 consists of a parity byte calculated bit-wise across a large number of bytes in a transmission transport frame. BIP-8 bits are set such that the overall data stre ...

GCC1/2 The general communication channel (GCC) was defined by G.709 is an in-band side channel used to carry transmission management and signaling information within optical transport network elements. Two types of GCC are available: * GCC0 – two byt ...

, TCM etc.). # OTUk is the section and includes framing, TTI, BIP8 and

GCC0 The general communication channel (GCC) was defined by G.709 is an in-band side channel used to carry transmission management and signaling information within optical transport network elements. Two types of GCC are available: * GCC0 – two byt ...

bytes. # FEC – The standard FEC code (described in G.975) is a Reed–Solomon coding calculated across the payload (OPU) columns. This allows detection and correction of bit errors due to signal impairments during transmission. The FEC code also extends the distance the optical signal can travel before requiring regeneration. G.709 offers advanced OAM&P capabilities such as Tandem Connection Monitoring (TCM), End to End performance monitoring, connectivity monitoring, signal quality supervision and

General Communication Channel The general communication channel (GCC) was defined by G.709 is an in-band side channel used to carry transmission management and signaling information within optical transport network elements. Two types of GCC are available: * GCC0 – two byt ...

(GCC).

Typical client signals and corresponding G.709 rates

Unlike SDH/SONET, the line rate is increased by maintaining the G.709 frame structure (4 rows x 4080 columns) and decreasing the frame period (in SDH/SONET the frame structure is increased and the frame period of 125 µs is maintained).

Notes and references

{{reflist

External links

Download the G.709 Recommendation
ITU-T recommendations ITU-T G Series Recommendations Optical Transport Network Telecommunications-related introductions in 2001

Typical client signals and corresponding G.709 rates

Notes and references

See also

External links