Open Transport Network (OTN) is a system that allows integration of heterogeneous traffic in a corporate network based on fiber optic communication channels.
Topology of network system (OTN) based on the basic "double ring" topology, in which the network nodes (multiplexers) are connected via dual “point-to-point” fiber-optic communication lines (FOL). These FOLs form two rings, via which transmitted information is circulating in opposite directions. In normal operation, all user data is transmitted via one ring (active one), while the second ring. The latter is in synchronization mode, to control the ability to backup. Backup ring may, in part or in whole, take transfer of all data transmitted via the active ring, if necessary in an emergency.
- Backbone - a double fiber-optic ring
- Universal slots for interface modules
- Hardware Signal Processing
- Distributed Architecture
- Time Division Multiplexing (TDM)
- Flexible bandwidth allocation
The main properties of OTN:
- The maximum network availability. During the expansion, adaptation or repair of the network, it remains in working condition due to:
• automatic reconfiguration
• universal nodes
• the automatic start
• interface modules.
- Direct access to the network and the guaranteed bandwidth
- Reliable connection
- A variety of interface modules
- Geographic extent of the network
- Flexible bandwidth allocation
- Simple Network corrections
- Rapid detection of errors and easy recovery of the network
- Receipt of information about any errors of the ring and interface modules operation in the network nodes (in the multiplexers) occurs at the central level and partially at the local level. It is provided by:
- The Network Management System
- Visual indication
- The Modular structure.
Architecture of communication network (OTN) based on five main components of the SIGMA fiber-optic transmission system:
- The infrastructure of fiber-optic cable (FOC)
- OTN nodes (multiplexers: SIGMA215, SIGMA22, SIGMA42)
- BORA network modules with common logic circuits (Broadband Optical Ring Adapters):
- BORA150-215-XY (X, Y = I, S, L, F), BORA600-215-XY (X, Y = I, S, L, F), BORA2500-215, BORA-215;
- BORA150-22-XY (X, Y = I, S, L, F), BORA600-1922-XY (X, Y = I, S, L, F), BORA2500-22, BORA-22;
- BORA622-X3M, BORA622-ETX, BORA2500-X3M, BORA2500-ETX, BORA2500-ULM150, BORA2500-ULM600;
- Interface modules that provide user access to the network connections;
- Control system of communications network, called as the OMS (OTN Management System).
The structure of the network connection nodes (OTN) corresponds to the configuration of multiplexers SIGMA fiber-optic transmission system. To accommodate modules, comprising in multiplexers, 19-inch shelves are used: S-215, S-1922, S-42. All of them support the installation of a number of common modules (PSU power modules, FAN vents module, BORA network module) and a set of interface modules:
- 4 interface modules in the S-215 shelf;
- 8 interface modules in the S-22 and S-42 shelves.
Common modules for the S-215 shelf are: PSU1Power Modules (active) and PSU2 (backup), FAN vents module and network module with common logic circuits (BORA Broadband Optical Ring Adapters), which may have fixed optics or a removable OTR optical transceivers.
Common modules for the S-22 shelf are: PSU1Power Modules (active) and PSU2 (backup), network module with common logic circuits (BORA Broadband Optical Ring Adapter), which may have fixed optics or a removable OTR optical transceivers.
Common modules for the S-42 shelf are: PSU1Power Modules (active) and PSU2 (backup), two network modules with common logic circuits (BORA Broadband Optical Ring Adapter), one of which is backup, and an additional NSM42 module of nodes support.
All modules are interchangeable blocks, front panels of which form the front panel of the multiplexer (OTN node).
PSU Power module generates the voltage necessary to power all the plug-in modules: +5 V, +12 V and -12V. There are different types of power modules that provide a connection of multiplexer to primary DC power supply with a rated voltage of 48V or to a primary AC power source with a rated voltage of 230V.
Vents module as part of each multiplexer provides the necessary temperature mode of operation of all electronic modules.
BORA Broadband Optical Ring Adapter is a network module, which ensures the time division multiplexing/demultiplexing (TDM) and sends received information to the appropriate interface module in the direction of reception, and in the direction of transmission - from the interface modules to the optical transceiver. It also implements algorithms for different system (network) functions such as reconfiguration and synchronization of the network. Its Random-Access Memory (RAM), protected from power failures, constantly keeps all information about the programmed connections.
Thus, each node in the network (multiplexer) has its own logic embedded in hardware. Failures, such as a cable break can be corrected very quickly (from 50 to 120 ms for SIGMA215 and SIGMA22, and less than 50 ms for SIGMA42) without interference of the CMS (OMS). After a full or partial power off the multiplexer, network connections can resume work without interference of the CMS, after the self test, the network right away becomes available.
Hardware product uses a variety of optical transceivers, depending on the distance to be covered, the necessary bandwidth of the network connections and optical characteristics of the cable. Optical transceiver modules are installed on the BORA network module, which can be equipped with fixed or replaceable (removable) optics, performing optical transmission and reception, electro-optical transition, encoding/decoding of component signals and clock recovery.
Following types of transceivers are available:
- Proper transceivers, not designed to work (interaction) with similar equipment of other manufacturers - OTR modules with different characteristics:
- Type of optical cable - Multimode and/or single-mode;
- Wavelength - 1310 nm or 1550 nm;
- Optical potential (several dozens of dB);
- Speed of optical signal transmission (bandwidth) - 150Mbps, 600Mbps or 2500Mbps.
- SDH Compatible transceivers, designed to work together with the standard SDH equipment.
All user equipment can be connected to the network connection through the appropriate interface connectors on interface modules, converting the user signals into digital signals that need to be placed and removed from the TDM frame of line signal to be sent into the ring. Modules can be removed and inserted while power is on (hot swap). Different types of interface modules to implement services related to the delivery of voice, data and video are available.