Open Transport Network
Encyclopedia
Open Transport Network (OTN) is a flexible private communication network, based on the fiber optic technology (ref) . It is a brand name and not to be mistaken with Optical Transport Network
. It is a networking
technology
that aims at transporting a number of communication protocols over an optical fiber
and is a mix of Transmission and Access NE. This includes serial protocols (e.g. RS232
) as well as telephony (POTS
/ISDN), audio, Ethernet
, video
and video-over-IP
(via M-JPEG, MPEG2
/4
, H.264 or DVB).
The basic building block of OTN is called a node. It is a 19" frame that houses and interconnects the building blocks that produce the OTN functionality. Core building blocks are the power supply and the optical ring adapter (called BORA : Broadband Optical Ring Adapter). The remaining node space can be configured with up to 8 (different) layer
1 interfaces as required.
OTN nodes are interconnected using pluggable optical fiber
s in a dual counterrotating ring topology
. The primary ring consists of fibers carrying data from node to node in one direction, the secondary ring runs parallel with the primary ring but carries data in the opposite direction. Under normal circumstances, only one ring carries active data. If a failure is detected in this data path, the secondary ring is activated. This hot standby topology results in a 1 + 1 path redundancy
. The switchover mechanism is hardware based and results in ultrafast (50ms) switchover
without service loss.
Virtual bidirectional
point-to-point or point-to-multipoint
connections (services) between identical interfaces in different nodes are programmed via a configuration software called OMS (OTN management system
). By doing this, OTN mimics a physical wire harness interconnecting electronic data equipment but with the added advantages typical for fiber transmission and with high reliability due to the intrinsic redundant concept.
This concept makes the Open Transport Network the de facto transmission backbone
standard for industrial high reliability communication sites that require errorfree communication for a large spectrum of protocols over long distances like pipelines, metros, rail, motorways and industrial sites.
The optical rings transport frames with a bitrate of (approximately) 150 Mbit/s (STM-1
/OC-3), 622 Mbit/s (STM-4/OC-12), 2.5 Gbit/s (STM-16/OC-48) or 10Gbit/s (STM-64/OC-192). The frames are divided into 32 kb payload cells that carry the servicedata from source to destination. Via the OTN management system, as many cells as required by the service are allocated to connections. This bandwidth allocation is transferred to the non-volatile memory
of the control boards of the nodes. As a result, the network is able to start up and work without the OMS connected or on line.
Optical Transport Network
ITU-T defines an Optical Transport Network as a set of Optical Network Elements connected by optical fibre links, able to provide functionality of transport, multiplexing, switching, management, supervision and survivability of optical channels carrying client signals...
. It is a networking
Telecommunications network
A telecommunications network is a collection of terminals, links and nodes which connect together to enable telecommunication between users of the terminals. Networks may use circuit switching or message switching. Each terminal in the network must have a unique address so messages or connections...
technology
Technology
Technology is the making, usage, and knowledge of tools, machines, techniques, crafts, systems or methods of organization in order to solve a problem or perform a specific function. It can also refer to the collection of such tools, machinery, and procedures. The word technology comes ;...
that aims at transporting a number of communication protocols over an optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
and is a mix of Transmission and Access NE. This includes serial protocols (e.g. RS232
RS-232
In telecommunications, RS-232 is the traditional name for a series of standards for serial binary single-ended data and control signals connecting between a DTE and a DCE . It is commonly used in computer serial ports...
) as well as telephony (POTS
Plain old telephone service
Plain old telephone service is the voice-grade telephone service that remains the basic form of residential and small business service connection to the telephone network in many parts of the world....
/ISDN), audio, Ethernet
Ethernet
Ethernet is a family of computer networking technologies for local area networks commercially introduced in 1980. Standardized in IEEE 802.3, Ethernet has largely replaced competing wired LAN technologies....
, video
Closed-circuit television
Closed-circuit television is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors....
and video-over-IP
Professional video over IP
Professional video over IP systems use some existing standard video codec to reduce the program material to a bitstream , and then to use an Internet Protocol network to carry that bitstream encapsulated in a stream of IP packets...
(via M-JPEG, MPEG2
MPEG-2
MPEG-2 is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods which permit storage and transmission of movies using currently available storage media and transmission...
/4
MPEG-4
MPEG-4 is a method of defining compression of audio and visual digital data. It was introduced in late 1998 and designated a standard for a group of audio and video coding formats and related technology agreed upon by the ISO/IEC Moving Picture Experts Group under the formal standard ISO/IEC...
, H.264 or DVB).
The basic building block of OTN is called a node. It is a 19" frame that houses and interconnects the building blocks that produce the OTN functionality. Core building blocks are the power supply and the optical ring adapter (called BORA : Broadband Optical Ring Adapter). The remaining node space can be configured with up to 8 (different) layer
Layer
Layer may refer to:* A layer of archaeological deposits in an excavation* A layer hen, a hen raised to produce eggs* Stratum, a layer of rock or soil with internally consistent characteristics...
1 interfaces as required.
OTN nodes are interconnected using pluggable optical fiber
Optical fiber
An optical fiber is a flexible, transparent fiber made of a pure glass not much wider than a human hair. It functions as a waveguide, or "light pipe", to transmit light between the two ends of the fiber. The field of applied science and engineering concerned with the design and application of...
s in a dual counterrotating ring topology
Ring network
A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring...
. The primary ring consists of fibers carrying data from node to node in one direction, the secondary ring runs parallel with the primary ring but carries data in the opposite direction. Under normal circumstances, only one ring carries active data. If a failure is detected in this data path, the secondary ring is activated. This hot standby topology results in a 1 + 1 path redundancy
Redundancy (engineering)
In engineering, redundancy is the duplication of critical components or functions of a system with the intention of increasing reliability of the system, usually in the case of a backup or fail-safe....
. The switchover mechanism is hardware based and results in ultrafast (50ms) switchover
Switchover
Switchover is the manual switch from one system to a redundant or standby computer server, system, or network upon the failure or abnormal termination of the previously active server, system, or network, or to perform system maintenance, such as installing patches, and upgrading software or...
without service loss.
Virtual bidirectional
Duplex (telecommunications)
A duplex communication system is a system composed of two connected parties or devices that can communicate with one another in both directions. The term multiplexing is used when describing communication between more than two parties or devices....
point-to-point or point-to-multipoint
Point-to-multipoint
Point-to-multipoint communication is a term that is used in the telecommunications field which refers to communication which is accomplished via a specific and distinct type of one-to-many connection, providing multiple paths from a single location to multiple locations.Point-to-multipoint is often...
connections (services) between identical interfaces in different nodes are programmed via a configuration software called OMS (OTN management system
Network management system
A network management system is a combination of hardware and software used to monitor and administer a computer network.Individual network elements in a network are managed by an element management system.-Tasks and operational details:...
). By doing this, OTN mimics a physical wire harness interconnecting electronic data equipment but with the added advantages typical for fiber transmission and with high reliability due to the intrinsic redundant concept.
This concept makes the Open Transport Network the de facto transmission backbone
Backbone
Backbone may refer to:* Vertebral column, of a vertebrate organism* Backbone chain, in polymer chemistry, the framework of the molecule* Backbone Entertainment, a video game development company* Backbone network, the top level of a hierarchical network...
standard for industrial high reliability communication sites that require errorfree communication for a large spectrum of protocols over long distances like pipelines, metros, rail, motorways and industrial sites.
The optical rings transport frames with a bitrate of (approximately) 150 Mbit/s (STM-1
STM-1
The STM-1 is the SDH ITU-T fiber optic network transmission standard. It has a bit rate of 155.52 Mbit/s. Higher levels go up by a factor of 4 at a time: the other currently supported levels are STM-4, STM-16, STM-64 and STM-256...
/OC-3), 622 Mbit/s (STM-4/OC-12), 2.5 Gbit/s (STM-16/OC-48) or 10Gbit/s (STM-64/OC-192). The frames are divided into 32 kb payload cells that carry the servicedata from source to destination. Via the OTN management system, as many cells as required by the service are allocated to connections. This bandwidth allocation is transferred to the non-volatile memory
Non-volatile memory
Non-volatile memory, nonvolatile memory, NVM or non-volatile storage, in the most basic sense, is computer memory that can retain the stored information even when not powered. Examples of non-volatile memory include read-only memory, flash memory, ferroelectric RAM, most types of magnetic computer...
of the control boards of the nodes. As a result, the network is able to start up and work without the OMS connected or on line.