ROADM equipment

The previous article analyzed the technical features of ROADM, and then introduced its equipment.

Taking Cisco 15454 as an example, the main boards of the device are introduced.

(1) 15454-TCC2P main control board (see Figure 1). The main control board provides the clock communication and network management control functions of the entire equipment, including system initialization settings, configuration, alarm, maintenance and fault diagnosis functions; manage all timing functions, including getting clock from BITs, getting clock from LINE, built-in clock, output clock; provide RSOH and MSOH termination, support 84 DCC channels; the control software and database exist in the TCC2P memory, which can monitor voltage and system, and support multi-chassis control; provide security function settings, and two control boards can achieve 1+1 protection.

ROADM equipment
Figure 1 – 15454-TCC2P main control board

(2) Optical cross plate (40-SMR2-C see Figure 2). The board also has built-in ROADM processing components, WXC optical cross-connect processing components, OSC processing components and optical amplifiers, and integrates the main technologies required by multi-dimensional ROADM networks on a single hardware board, and the deployment is very flexible. SMR2 has built-in WXC components and has multi-dimensional optical crossover capability.

ROADM equipment
Figure 2 – 40-SMR2-C module introduction

The ONS 15454’s single-module ROADM module operates in the ITU 100-GHz wavelength range. Each card integrates automatic channel power monitoring and control, providing input and output ports for node and network-based automatic power stage management. The selection of the optical path of each channel is also through the wavelength channel configuration (WPP), a complete automatic way at the network level, using a terminal-to-terminal and click wavelength configuration, easy-to-use SDH wavelength management, etc.

(3) Optical monitoring processing board (OSCM). The optical interface performance of the optical monitoring board is: STM-1 signal mode (155M) 1510nm; support 37dB attenuation, that is, it can transmit 150km. The OSC (optical supervision control) signal processing function of the optical monitoring board: send the OSC signal to the TCC board for processing; the OSC overhead D1-D3 is used to manage the DWDM network. VOA (varuiable optiacal amplify) adjusts the OSC light emission, matching the receiving sensitivity of the opposite end (ROADM). Provide 100M fast Ethernet user data channel. The functional modules in the OSCM optical board are shown in Figure 3, and the panel slot insertion method of the DWDM common board is shown in Figure 4.

ROADM equipment
Figure 3 – Functional block diagram of OSCM optical board
ROADM equipment
Figure 4 – DWDM common board (TCC2P main control board and OSCM optical channel board) panel slot insertion method

(4) Optical wavelength conversion module (0TU2-XP). OTU2 has two user ports and two uplink ports connected to ROADM modules, all ports are designed with XFP optical modules, and the type used for access (such as STM64 and 10GE) can be adjusted by replacing optical modules. The uplink port connected to the ROADM module also adopts the method of XFP optical module. The configured XFP optical module can adjust the wavelength of the uplink to the ROADM through software, and the wavelength range can be adjusted arbitrarily within 40 channels, which reflects the flexibility of the wavelength division system design.

The 10G optical transport network XPonder is a single slot board, a plug-in interface device based on four-port 10Gbit/s XFP light. The client data of the OTU2-XP flows to the trunk trunk through a transceiver similar to that common to the application.

The technical characteristics of OTU2-XP can be summarized as follows:

1) All 4 interfaces support multiple services: OC-192/STM-64 (9.95328G/bps); 10G WAN PHY (9.95328G/bps); 10G LAN PHY (10.3125G/bps); 10 Gigabit FC (10.518G/bps).

2) 0TU-2: Support standard G.709 (10.70923G/bps); support G.709 to 10GE overclocking transmission (11.0957G/bps) defined by Article 7.1 of ITU-TG.Sup43; support G.709 to 10GE overclocking transmission (11.0491G/bps) defined by Article 7.2 of ITU-TG.Sup43; support G.709 patent overclocking mode transmission 10GF (11.3168G/bps).

3) Port specifications: All 4 ports support modes without FEC and FEC (Reed-Solomon standard FEC defined by ITU-TG.975); support E-FEC enhanced forward error correction algorithm.

(5) Optical channel multiplexer/demultiplexer (MD-40-ODD) is shown in Figure 5. 40-channel multiplexer/demultiplexer, one optical multiplexer/demultiplexer for each optical direction, is used to combine multiple optical channels. The wave is sent to the ROADM card, and vice versa, the combined wave signal sent by the ROADM card is demultiplexed.

ROADM equipment
Figure 5 – Optical channel combiner-demultiplexer

(6) Dispersion Compensation Unit (DCU). There are two types of dispersion compensation units: fixed and adjustable, and adjustable can be divided into two types: coarse adjustment and fine adjustment.

A 15216-DCU device (fixed dispersion compensator) is commonly used in the C-band, as shown in Figure 6(a).

The ONS 15454 tunable DCU adjustable dispersion compensation board is shown in Figure 6(b). 15454-TDC-FC is fine adjustment, the adjustment range is 45~675ps/nm, and the change value of each step is 45ps/nm; 15454-TDC-CC is coarse adjustment, the adjustment range is 110~1650ps/nm, and the change value of each step is 110ps/nm.

ROADM equipment
Figure 6 – 15216-DCU Fixed Dispersion Compensator (a); Dispersion Compensator (b)

(7) Multi-directional connection module (PP-4-SMR). Nodes with more than two optical directions need to use a multi-directional connection module, which is a passive device and is used for signal forwarding between multiple optical directions. The actual object is shown in Figure 1(a), and the connection principle is shown in Figure (b).

ROADM equipment
Figure 7 – Multidirectional connection module

(8) Power access board (E-CIP-MIC48V). The power access board provides the following functions: power access and MIC-A/P FMEC1+1 redundancy; serial access; LAN port access; two BITS access and BITS output.

(9) Power access module (E-AP-MIC48V). The power access module provides the following functions: power access and MIC-C/T/P FMEC1+1 protection redundancy; 8 warning outputs, and the warning information is provided by the TCC2P card.