DE10208747A1 - Universal cross connector - Google Patents

Abstract

The cross connector contains a first switching matrix (VC-KF) for signals of the synchronous digital hierarchy SDH and a transparent switching matrix (OTN-KF) for optical transport signals. DOLLAR A Both switching matrixes are connected to each other by converter devices (U10, U11), so that a transition between the two networks is possible and only if necessary is implemented.

Description

The invention relates to a universal cross connector for A synchronous digital hierarchy and network signals for signals of an optical transport network it concerns also a universal cross connector only for signals from the optical transport network.

In the regional transmission networks in Europe Transmission systems used after the synchronous digital Hierarchy, SDH, according to ITU recommendation G.707 work. In North America, systems are manufactured according to the SONET standard used, which is also specified in ITU recommendation G.707 are. These regional networks are mostly in ring structures built up in the synchronous digital hierarchy Transmission bit rates of 155 Mbit / s for STM-1 signals, 622 Mbit / s for STM-4 signals, 2.5 Mbit / s for STM-16 signals up to 10 Gbit / s for STM-64 signals. Higher transfer rates are aimed for. The transmitted in these networks Useful signals are packed in so-called virtual containers VC-n, with granularities of 2 Mbit / s for the virtual container VC-12, 34 Mbit / s for VC-3 and 140 Mbit / s for VC-4 containers the SDH standard; with the SONET standard with granularities of 1.5 Mbit / s for VC-11, 6 Mbit / s for VC-2 and 45 Mbit / s for VC-3 Container.

To connect the individual rings in the regional network often cross connect systems used these virtual containers from any Scan through input ports to any output ports can.

In the national network, wavelength Multiplex procedures each from a variety of SDH / SONET Signals with data rates of 2.5 Gbit / s, 10 Gbit / s and in in the near future also 40 Gbit / s transport signals formed. in this connection are either higher order SDH / SONET signals (STM-16/64/256) or signals according to the new ITU standard G. 709. According to the recommendation G. 709 STM-16/64/256 Signals in addition to overhead information and additional Control bits for error correction, FEC, for OTU-1/2/3 signals extended. Several of these signals become one Wavelength division multiplex signal, WDM, combined and in one optical transport network, OTN. The optical Transport networks are consistently meshed networks with a dot to point connections between the individual network elements built up. The granularity of the signals in the OTN is STM 16/64/256 or OTU-1/2/3, d. that is, the smallest bit rate that is in the OTN can be switched is 2.5 Gbit / s. Here too are optical cross connect systems for the distribution of Useful signals provided.

For the transition between the regional SDH / SONET network (in Hereinafter referred to as the SDH network) and the national one "Optical network" should be given a cross connector, which offers a high degree of flexibility and is inexpensive is feasible.

To implement cross connect functions in the optical field Transport network is also said to be a simplified facility can be specified.

In addition, should also in the optical transport network Switching through with a finer granularity are made possible a finer granularity in the distribution of the useful signals allows.

The main task is performed by a cross connector system solved the features of claim 1.

A cross connector for the optical transport network is in the independent claim 3 specified.

The main advantage of the invention is two Coupling fields and converters reached. OTN line connections are on Connections of an OTN switching matrix switched on and SDH Line connections to an SDH switching matrix. These switching fields can switch through OTN signals or SDH signals. The converters enable switching operations between SDH and OTN data formats. OTN switching matrix signals can also be used an SDH granularity. Since translators are only in If needed, this solution is special inexpensive.

When using multiple converters you can also different OTN formats are switched.

Are different OTN formats - and due to this - Different OTN switching matrix signals are used transparent switching matrix useful and several converter types required.

With the OTN Crossconnector, which only uses OTN formats the same advantages apply. With the help of SDH / SONET switching matrix can with a finer granularity be switched.

Other advantageous developments of the inventions are in the remaining subclaims and in the description explained in more detail.

Various embodiments of the invention are based on explained in more detail by figures.

Show it

Fig. 1 is a SDH / SONET network and an OTN network with cross-connect devices,

Fig. 2 shows a universal cross-connector,

Fig. 3 shows a variant with a plurality of OTN signals switching network,

Fig. 4 is a simplified cross-connector for STM-16 signals,

Fig. 5 is a simplified cross-connector for ODU-1 signals,

Fig. 6 is a cross-connector and OTN

Fig. 7 is an enlarged cross-connector OTN.

Fig. 8 shows the frame structure of an STM-N signal and VC-4 container and

Fig. 9 shows the frame structure of the ODU / OTU signal.

Fig. 1 is a SDH / SONET network shows SDH-N with several ring networks STM-4-N, STM-16 N different data rates, each having a plurality of add / drop multiplexer ADM. These networks are connected via a cross connector CC-SO to an optical transport network OTN which has a plurality of optical network elements ONE and further cross connectors CC-SO2, CC-SO3 and an OTN cross connector CC-O.

The Crossconnector CC-SO enables both flexible Interconnection of SDH / SONET signals STM-N in the SDH network as well flexible interconnection of optical transport signals of the OTN network and also serves as a connection between two networks.

The cross connector CC-SO is an object of this invention. The principle underlying this invention was also in the OTN Crossconnector CC-O used to different Data formats of the optical transport network OTN into each other convict and distribute.

Fig. 2 shows a symbolic representation of the cross connector CC-SO. This contains two coupling fields VC-KF and OTN-TKF which correspond to one another via converter devices U10, U11, U21 and for different data formats and with connection circuits which connect the cross-connector to both networks.

The first switching matrix VC-KF is for synchronous signals Digital hierarchy STM-N is designed and is below referred to as VC switching matrix. Even with the Signal names are limited to SDH signals as an example although the switching matrix can also be designed for SONET signals can. The transport signals (transport modules) STM-N are on the SDH connections (inputs and outputs each) AS1 to ASm received and sent. At switching network connections (input and Outputs), port circuits PS1 to PSm are switched on the received STM transport signals according to the ITU Process recommendations, d. that is, regenerator and Multiplexer section overhead, RSOH and MSOH, terminated and the useful signals in the form of virtual containers VC-4 at SDH (or VC-3 at SONET) can be recovered.

The format of the STM-N transport modules and the container VC-4 contained therein by N is shown in FIG. 8 and corresponds to FIG. 8-8, ITU recommendation G.707, 03/1996. A repositioning of the useful signals is also required in order to adapt them to the clock rate of the cross connector CC-SO. This means that the pointer of the incoming signal, which points to the first byte of the virtual container, is recalculated in accordance with the phase and frequency of the frame clock of the SDH switching matrix. The signals treated in this way are routed to the VC switching matrix as switching matrix signals ISDH.

The internal switching field signals ISDH preferably have one SDH-like structure, but include, for example not the regenerator and section overhead. They match such as the VC-4 container, possibly supplemented by internal ones Switching network information.

In the transmission direction are through the port circuits PS1 to PSm in a corresponding manner ISDH or modified VC-4 or VC-3 signals multiplexed and adding the Multiplexer and regenerator section overheads STM-N signals formed.

Fig. 2 is therefore to be understood as a schematic diagram for both transmission directions, both received at the at the terminals AS1 to ASn signals are also sent out as. This form of presentation is also common in the ITU recommendations.

The VC switching matrix VC-KF initially enables the permissive Interconnection (cross-connection) of certain specific containers assigned electrical switching network signals ISDH between any port connections and thus between any SDH Connections AS1 to ASm.

The VC switching matrix is now logical (i.e. directly or via the OTN switching network) via the converter devices U10, U11, U21 connected to the OTN switching matrix. This is in this Exemplary embodiment as a transparent switching matrix OTN-TKF executed because there are different formats of OTN Switching matrix signals, for example ODU-1 (Optical Data Unit) and STM-16, must switch through in electrical form. This Signals are, for example, from optical transport signals OTU-1, OTU-2 by demultiplexing and possibly implementation obtained in another data format or via a separate channel has been transmitted. The OTN Switching matrix signals can also be internal Switching matrix information included.

The OTN switching matrix signals can also directly or after Conversion to another OTN data format, for example OTU-1 in STM-16, distributed in the OTN switching matrix and over Different OTN connections AO1 to AO4 in the optical Transport network are forwarded. But you can also via conversion devices U10 and U11 to the VC switching matrix VC-KF be switched through.

The U10 converter function is one-way an ISDH signal bundle coming from the VC switching matrix, consisting from 16 VC-4 or 48 VC-3 signals, adding the required overheads RSOH and MSOH to an STM-16 signal to be completed, then in the transparent OTN switching matrix can be switched through arbitrarily and thus a connection between the SDH network and the OTN.

In the opposite direction in the converter U10 from the optical Transport network OTN terminates incoming STM-16 signals, the 16th VC-4 or 48 VC-3 signals are repositioned to the Clock rate of the VC switching matrix VC-TKF adjusted, so in VC- Switching network signals ISDH implemented to over the VC switching network to get into the SDH network.

The converter device U11 has the task of initially supplementing an ISDH signal bundle in one direction by adding overheads RSOH and MSOH to an STM-16 signal. By adding the "Optical Channel Payload Unit Overhead" OPU OH and the "Optical Channel Data Unit Overhead" ODU OH, an ODU-1 signal is formed which can be switched through in the OTN switching matrix ( FIG. 9). In the opposite direction, the ODU-1 signal is first terminated in the converter U11 and the recovered STM-16 signal is processed further, as in the converter U10, to form an ISDH switching matrix signal.

Due to the interaction of both switching fields, there is also a Switching of OTN signals with VC-4/3 granularity possible, by an OTN switching matrix signal via a converter and that VC switching network and then via this converter or another converter into an OTN switching matrix signal implemented in the OTN network.

In addition, the converter device U21 makes it possible different OTN switching network signals ODU-1 and STM-16 via to switch through the transparent OTN switching matrix and this to implement each other. This implementation can also be done through the both conversion devices U10 and U11. The In one direction, the converter function of U21 is a STM-16 signal by adding overheads to an ODU-1 Implement signal that is in the transparent OTN switching network OTN TKF can be interconnected. In the opposite direction, the ODU-1 Signal terminates and the recovered STM-16 signal can again in the transparent switching matrix.

For the implementation of data formats are also to the Network connection circuits connected to the OTN switching network NA11 provided up to NA2n.

The network connection circuits NA11-NA1n each convert ODU-1 signals into optical channel transport units OTU-1 signals in the transmission direction. For this purpose, an OTU overhead OTU-OH and an OTU forward error correction section OTU-FEC are added to the ODU-1 signal. FIG. 9 shows the pulse frame including the overhead of an OTU-1 signal. An explanation of the abbreviations is not necessary here, since these are not essential to the invention.

Through an electrical / optical conversion of the Mains connection circuits NA11-NA1n with optical signals certain wavelengths λ1 to λn generated in a Wavelength division multiplexing device W1 for an "optical transport Module "Signal OTM-1 can be summarized and sent. In The direction of reception is first split up Wavelength-multiplexed signal. Then in each case Mains connection circuits performed an error correction; the OTU overhead OTU-OH is terminated and from OTU-1 signals become ODU-1 signals with wavelengths λ1 to λn recovered.

The mains connection circuits NA21 to NA2n have additional ones Multiplex and demultiplex facilities with which in Transmission direction 4 ODU-1 signals to one ODU-2 signal be summarized. For this, the 4 ODU-1 signals are switched on corresponding overhead and corresponding correction bytes added. After an electrical / optical conversion, the optical output signals of the power supply circuits an optical transport module signal OTM-2 combined. In In the direction of reception, the OTM-2 signal becomes signals obtained with wavelength λ1 to λn and in the Mains connection circuits after error correction and termination ODU-1 Signals won.

Instead of multiplexing 4 ODU-1 signals into one OTU-2 Signal can of course also multiplex and from 16 ODU-1 Signals are provided in an OTU-3 signal.

Other mains connection circuits, the transponders TR1 to TRn, each convert an electrical STM-16 in the transmission direction Signal into an optical signal with a certain Wavelength λ1 to λn um. The optical signals are in one Wavelength division multiplexing device W3 to a WDM signal WDM 1 summarized. In the receiving direction, the signal WDM-1 filter individual signals with wavelengths λ1 to λn obtained and in a transponder in electrical STM-16 Signals converted back.

For higher transfer rates than Network connection circuits multiplex devices MUX1 to MUXn provided in Direction of transmission 4 STM-16 signals each to an optical STM-64 signal with specific wavelengths λ1 to λn sum up. The STM-64 signals are in one Wavelength division multiplexing device W4 multiplexed to form a signal WDM-2. In Receive direction is a received WDM-2 signal in Individual signals λ1 to λn divided and in the Multiplex devices MUX1 to MUXn divided into electrical STM-16 signals.

Instead of multiplexing four STM-16 signals into one STM-64 signal can of course also multiplex 16 STM 16 signals into an STM-256 signal etc. by accordingly designed multiplex facilities are provided.

The signals are transmitted via corresponding OTN connections AO1 to AO4 broadcast.

The switching networks, converters, port circuits and Mains connection circuits are controlled by a control CON or by controlled by a management system.

FIG. 3 shows a variant of the cross connector in which STM-16 and OTU-1 signals are permitted as OTN switching matrix signals. The OTU-1 signals are obtained by optoelectric conversion and, if necessary, by additional demultiplexing from received optical transport signals OTM-1 or OTM-2 signals. The OTU-1 signals can be distributed directly via the OTN switching matrix or fed to a converter device U22, which converts them into STM-16 signals. Due to the STM-16 / OTU-1 implementation, the effort in the network connection circuits is lower, but the signals switched through between different network elements cannot be monitored so effectively, especially with only implemented OTU-1 signals, since no termination and no error correction takes place ,

One takes place in the converter devices U10 and U12 Implementation in VC switching matrix signals. You can also get one here Error correction are carried out or in the transmitter direction appropriate coding.

Fig. 4 also shows a cross connector. However, this is simpler because only one data format ODU-1 is switched through in the OTN switching matrix OTN-KF. This is obtained from the received optical transport modules OTM-1 or OTM-2 by appropriate network connection circuits NA11 to NA1n or NA21 to NA2n, which additionally contain time-division multiplexing devices. Since only one data format needs to be switched in the OTN switching matrix, it is therefore not necessary to use a transparent switching matrix, but a conventional switching matrix can be used. Only a single converter device U11 is required, the ISDH connections of which can be connected directly to the VC switching matrix VC-KF. The VC switching matrix again creates a transition between the two networks. It is also possible to switch within the optical transport network with VC-4/3 granularity.

FIG. 5 shows a further variant in which signals are switched through as switching matrix signals STM-16 and likewise only one converter device U10 is provided.

Fig. 6 shows an OTN Crossconnector CC-O, which is not designed for the transition of data from the OTN network to an SDH network. The OTN switching matrix OTN-TKF is designed as a transparent switching matrix because different data formats, here ODU-1 and STM-16, are to be switched through. The network connection elements NA11 to NA2n correspond to those from FIG. 2. Only one converter device U21 is provided, which can convert a plurality of STM-16s into ODU-1 signals and vice versa. This enables an arbitrary distribution of the data streams in the optical transport network OTN, whereby usually only a few converters are required.

Fig. 7 shows an extended OTN Crossconnector CC-OE, but which also contains the VC switching matrix VC-KF. In addition to the STM-16 / ODU-1 converter device U21, there are other known converter devices U10 and U11 which convert STM-16 and ODU-1 formats into the ISDH format. Received optical transport signals OTM-1, OTM-2, WDM-1, WDM-2 are converted into OTN switching network signals ODU-1, STM-16 and fed to the converter devices U11 and U10 via the OTN switching network and converted into ISDH format. From there they arrive in the VC switching matrix VC-KF. In the VC switching matrix VC-KF, the ISDH signals are regrouped to the converters U11 and U10, converted there into OTN switching matrix signals and fed back into the optical network via the OTN switching matrix and the network connection circuits. It is therefore possible to distribute the signals in the OTN network again with the granularity of an ISDH signal (VC-4/3 container).

Claims (10)

1. Universal cross connector (CC-SO) for STM-N signals of an SDH network (SDH-N) of a synchronous digital hierarchy [SDH, SONET] and for signals of an optical transport network (OTN), characterized in that
that a VC switching matrix (VC-KF) is provided for switching VC switching matrix signals (ISDH) of the synchronous digital hierarchy between its connection points,
that an OTN switching matrix (OTN-TKF) is provided for switching OTN switching matrix signals (STM-16, OTU-1, ODU-1) of an optical transport network (OTN) between its connection points,
that at least one converter device (U10, U11, U12), which converts bidirectionally OTN switching matrix signals (STM-16, OTU-1, ODU-1) into VC switching matrix signals (ISDH), between the OTN switching matrix (OTN-TKF) and the VC switching network (VC-KF) is logically switched on, so that connections between the SDH network (SDH-N) and the optical OTN transport network (OTN) under implementation of the data format and a granularity of the VC switching network (VC-KF ) are switchable. 2. Universal cross connector (CC-SO) according to claim 1, characterized, that at least one further converter device (U21, U22) for a bidirectional implementation of OTN switching matrix signals (STM-16) into other OTN switching matrix signals (ODU-1, OTU- 1) are provided. 3. Universal cross connector (CC-O) for signals of an optical transport network (OTN), characterized in that
that an OTN switching matrix (OTN-TKF) is provided for switching OTN switching matrix signals (STM-16, ODU-1),
that at least one converter device (U21) is connected to the OTN switching matrix (OTN-TKF), which converts bidirectionally OTN switching matrix signals (STM-16) into other OTN switching matrix signals (ODU-1). 4. Universal cross connector (CC-O) according to claim 3, characterized in
that in addition a VC switching matrix (VC-KF) is provided for switching VC switching matrix signals (ISDH), and
that at least one further converter device (U10, U11) between the OTN switching matrix (OTN-TKF) and the VC switching matrix (VC-KF) is logically switched on, the bidirectional OTN switching matrix signals (STM-16, ODU-1) in VC - Converting network signals (ISDH), so that connections with a granularity of the VC switching network (VC-KF) are possible. 5. Universal cross connector according to one of the preceding claims, characterized in that
that the OTN switching matrix is designed as a transparent switching matrix (OTM-TKF),
that several converter devices (U10, U11, U12) for bidirectional conversion of different OTN switching matrix signals (STM-16, ODU-1, OTU-1) to VC switching matrix signals (ISDH) and / or several converter devices (U21, U22) for one bidirectional conversion of OTN switching matrix signals (STM-16) into other OTN switching matrix signals (ODU-1, OTU-1) are provided. 6. Universal cross connector according to one of the claims 1-4 characterized that the OTN switching matrix (OTN-KF) for a single format of OTN switching matrix signals (ODU-1, STM-16, OTU-1) as non-transparent switching matrix is formed. 7. Universal cross connector according to one of claims 1, 2, 5, 6, characterized, that the VC switching matrix (VC-KF) via port circuits (PS1-PSm), the bidirectional transport signals (STM-N) of the Synchronous Digital Hierarchy (SDH) in electrical VC Convert coupling signals (ISDH) to the SDH network (SDH-N) is switched on. 8. Universal cross connector according to one of the previous ones claims, characterized, that the OTN switching matrix (OTN-TKF; OTN-KF) via Mains connection circuits (NA-11-NA-1n; NA-21-NA-2n; TR1-TRn; MUX1- MUXn), the bidirectional electrical OTN switching matrix signals (STM-16, OTU-1, ODU-1) into optical transport signals (STM-16, STM-64, OTU-1, OTU-2) to implement the optical Transport network (OTN) are switched on. 9. Universal cross connector according to claim 8, characterized, that wavelength division multiplexers (W1-W4) to the Mains connection circuits (NA-1-NA-1n; NA-21-NA-2n; TR1- TR n; MUX1-MUXn) are connected, which is bidirectional optical transport signals (STM-16, STM-64, OTU-1, OTU-2) in Wavelength division multiplex signals (OTM-1, OTM-2, WDM-1, WDM-2) implement. 10. Universal cross connector according to one of the preceding Expectations, characterized, that the VC switching network signals (ISDH) directly or via the OTN switching network (OTN-TKF) to the converter equipment (U10, U11, U12).