OTN equipment

After understanding the technical features of OTN, let’s talk about OTN equipment.

At present, OTM stations and OLA stations are common in the network. The OTM station is a station that can add and drop services, and the OLA station is a station that does not need to add or drop services, but only serves as a station for optical signal relay and amplification.

(1) 0TN station. Connect the client-side signal (10GE signal of the switch) to the OUT board of the OTN device (the OUT board is actually composed of tributary boards, cross-connect boards, and line boards that convert service encapsulation into wavelengths). The output of the OUT board is a single-wavelength wavelength that conforms to the OTN standard. The first to 40th wavelengths can be selected (each wavelength can only be used once, and the frequency of each wavelength is different). Multiple OUT boards access many services and output multiple single-wavelength signals (the maximum output of 40-wave system is 40 waves). After all the single-wave signals pass through M40 (multiplexer with 40 waves) and D40 (divider with 40 waves), the 40 sub-wave signals are gathered into a pair of optical fibers, and then the signals are subjected to optical amplification and dispersion compensation processing. At the same time, the monitoring signal is connected, and the signal is sent into the backbone fiber to the peer site, and the peer site reverses the process. The schematic diagram of the OTM station is shown in Figure 1.

 OTN equipment
Figure 1 – Schematic diagram of OTM station

(2) OLA station. The function of OLA is to re-amplify the weaker signal in the optical path, mainly through a common erbium-doped optical fiber amplifier (EDFA). OLA does not do any processing on the electrical layer of the business, so its cost is low, it does not involve business, and it is convenient for construction and maintenance. The OLA site is also a node in the network and also needs to transmit monitoring signals. Therefore, the FIU and SC boards for optical monitoring are also configured. The schematic diagram of the OLA site is shown in Figure 2.

OTN equipment
Figure 2 – Schematic diagram of OLA station

(3) A typical configuration description of Huawei OTN equipment. The following uses Huawei OptiX OSN6800 as an example to introduce the optical transmission subframe and main boards of the OTN equipment.

① OptiX OSN 6800 subrack.

Figures 3 is the interface diagram of the main subrack of the OSN6800 subrack. The OSN6800 subrack is used to place the single board of the optical layer in each optical direction, the multiplexer M40, the demultiplexer D40, the optical amplifier OA, the monitoring SC and the FIU, etc.

OTN equipment
Figure 3 – The interface diagram of the main subrack of the OSN6800 subrack

② OSN6800 board. The OSN6800 board is mainly composed of optical wavelength conversion boards, OTN tributary boards, OTN line boards, PID boards, cross-connect and system control communication boards, optical multiplexing and demultiplexing boards, fiber amplifier boards, optical monitoring channel boards, optical protection boards, spectrum analysis boards, and clock units.

Among them, optical wavelength conversion boards can be divided into enhanced communication interface boards (TN11ECOM), 4×GE line capacity wavelength conversion boards (TN11L4G), single-transmitting, single-receiving dual-channel GE service aggregation boards (TN11LDGS), Dual-transmit, selective-receive, dual-channel GE service aggregation board (TN11LDGD), 2-channel arbitrary-rate service aggregation wavelength conversion board (TN12LDM), dual-transmission, selective-receive 2-channel arbitrary-rate service aggregation wavelength conversion board (TN11LDMD), 100Gbit/s wavelength conversion board (TN12LSC), 40Gbit/s wavelength conversion board (TN11LSQ), etc.

OTN tributary boards can be divided into 10 Gigabit Ethernet tributary boards (TN11TBE), 2-channel GE tributary service processing boards (TN11TDG), 2-channel 10G tributary service processing boards (TN11TDX), 4-way STM-16/0C-48/0TU1 tributary service processing board (TN11TQS), 40G tributary service processing board (TN11TSXL), etc.

OTN line boards can be divided into two-way 10G line service processing board (TN11ND2), 4-way 10G line service processing board (TN51NQ2), and 10G service processing board (TN11NS2).

PID boards can be divided into PID comb filter board (C-band)-200/100GHz (TN11BMD4), PID comb filter board (C-band)-200/50GHz (TN11BMD8), 4×OTU2 electrical processing boards (TN12ELQX) with 4×10G client-side optical ports, 12-channel optoelectronic integrated boards (TN12PTQX) with 4×10G client-side optical ports, etc.

Crossover and system control communication boards can be divided into centralized crossover board (TN11XCS), system control and communication board (TN11SCC), etc.

Optical multiplexing and demultiplexing boards can be divided into OADM access boards (TN11ACS), 40-wavelength demultiplexing boards (TN11D40), 40-wavelength multiplexing boards (TN11M40), and optical fiber line interface boards (TN11FIU).

Optical fiber amplifier boards can be divided into dual optical amplifier units with monitoring channel function (TN11DAS1), optical power amplifier boards (TN11HBA), etc.

The optical supervisory channel board can be divided into high-power one-way optical supervisory channel board (TN11HSC1), single-channel optical supervisory channel board (TN11SC1) and so on.

Optical protection boards can be divided into dual optical channel protection boards (TN11DCP) and synchronous optical communication separation boards (TN11SCS).