ROADM technical features
The function of the reconfigurable optical add-drop multiplexer (ROADM) is similar to the network element of the ADM optical layer of SDH, which can complete the adding and dropping of the optical channel on one node, and the cross-scheduling of the wavelength level between the optical channels; It can remotely control the ROADM subsystem in the network element through software to realize the configuration and adjustment of the add and drop wavelengths, and the power of the service wavelength can also be managed.
ROADM technology supports chain, ring, lattice, and multi-ring topologies; supports linear (supports 2 optical transceiver lines and local upper and lower) and multi-dimensional (supports at least 3 optical transceiver lines and local upper and lower) node structure; in the case of no manual on-site deployment, the wavelength can be added and dropped and the pass-through configuration can be realized, which increases the flexibility of the optical network and simplifies the difficulty of network planning; the minimum granularity of long scheduling is 1 wavelength, which can support scheduling and adding/dropping of any wavelength combination, and scheduling and adding/dropping of any direction and any wavelength combination; ROADM equipment is flexible, can fully meet the dynamic needs of data services, is easy to achieve network expansion, and gradually increase investment with business development; ROADM improves work efficiency and responds to new customer demands by providing node reconfiguration capability, while effectively reducing operation and maintenance costs; ROADM adopts ASON/GMPLS control plane, supports multiple network protection/recovery, and has strong survivability; the remote unified network management supports automatic management of optical power and end-to-end wavelength management.
OTN technical features
OTN provides sub-wavelength cross-scheduling based on the electrical layer and wavelength cross-scheduling based on the optical layer, providing powerful service grooming and scheduling capabilities. On the electrical layer, the ODUk-based crossover function increases the granularity of circuit switching from 155M in SDH to 2.5G/10G/40G for flexible scheduling and protection of large-granularity services, and completes sub-wavelength service scheduling on the electrical layer. On the optical layer, the scheduling of wavelength services is realized by ROADM. OTN can realize fast protection of wavelengths or sub-wavelengths, such as 1+1(1 main and 1 hot standby), 1:1(1 main and 1 cold backup), 1:N(N main and 1 cold standby), mesh protection, and meet the protection switching time of 50ms required by carrier-class services. OTN provides service access capabilities such as IP, SAN, video, and SDH, which can realize transparent transmission of services and efficiently multiplex and encapsulate services. OTN defines a wealth of overhead bytes, so that WDM has the same operation and maintenance management capabilities as SDH. Among them, the multi-layer nested Tandem Connection Monitoring (TCM) function can realize the monitoring of complex networks such as nesting and cascading; it supports the loading of the GMPLS (generalized multiprotocol label switching, generalized multiprotocol switching flag) control plane, thereby forming an OTN-based ASON (automatically switched optical network, automatic optical switching network) network. The SDH-based ASON network and the OTN-based ASON network use the same control plane, which can realize an end-to-end, multi-layer intelligent optical network. There are two common OTN equipment in the network at present.
