JP2919214B2 - 0/1 system instantaneous interruption switching system in ATM communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Async) based on SDH (New Synchronous Digital Hierarchy).
The present invention relates to a 0/1 system uninterruptible switching system by constantly adjusting the phase of a user cell in a strong transfer mode communication system.

[0002]

2. Description of the Related Art SDH is a hierarchy of multiplexed digital signals defined in CCITT recommendations G707, G708 and G709 as international standards. The ATM communication method is a type of packet communication called an aperiodic transfer method and is characterized by high-efficiency communication using fixed-length packets.

[0003] ATM conveys information to be transmitted in fixed-length blocks called user cells or simply cells. The cell is composed of a header part and an information field part, and the header part stores an identifier indicating a destination which is a destination of information. This cell is mapped to an SDH-based AU-4 (administrative unit-4), multiplexed and transmitted. The AU-4 is composed of a payload carrying information such as cells, a path overhead POH, and a pointer in a digital hierarchy at a speed of 150M, and a section overhead SO used for line maintenance and management.
STM-1 which becomes the baseband of the transmission path by adding H
(Synchronous Transport Mo
dule-1). The signal format of STM-1 is composed of a signal of 270 × 9 = 2530 bytes per frame. Also, N AU-4s (4 or 1)
6) In some cases, STM-N at a higher level is configured by multiplexing.

[0004] Each cell of the ATM is mapped to the payload of the AU-4. At this time, the positional relationship between the head of the frame and the cell is arranged asynchronously and freely. In the B-ISDN (Broadband Integrated Digital Communication Network) scheduled in the future, the ATM communication system based on this SDH is scheduled to be adopted. (B
-Refer to the supervision of ISDN Ohm Co., Ltd., supervised by Hideyoshi Tominaga.) Conventionally, in this type of ATM communication system, when a 0/1 transmission line is used, it is necessary to switch between these two systems without instantaneous interruption. It is necessary to synchronize between the assigned user cells. As a method of establishing this synchronization state, first, the phases of the constituent bits of the user cells of both systems are compared to detect a phase difference, and a delay cell is inserted into the system side where the phase has advanced to match the phases.

[0005]

As described above, in the prior art, since the constituent bits of the user cells are compared for the detection of the phase difference between the 0/1 system, the data of the user cells has the same code. In this case, bit comparison cannot be performed. Also, it takes time to determine which system is delayed, so that it takes time to detect. For this reason, since it takes time until the synchronization state is established, there is a problem that instantaneous interruption switching may not be realized.

[0006]

SUMMARY OF THE INVENTION A 0/1 system instantaneous interruption switching system in an ATM communication system according to the present invention is a 0/1 system instantaneous interruption switching system in an ATM communication system based on SDH (new cycle digital hierarchy). In the system, the transmission path transmitting apparatus virtually adds a user cell number to a user cell outside the cell within the apparatus and replaces the user cell number of the first user cell included in the STM-1 signal with the user cell number of the STM-1 signal. Inserted into a part of the overhead and transmitted to the partner station, and the user cell number of the first user cell included in the STM-1 signal is restored in each of the 0 system and the 1 system from the information of the overhead of the transmission path receiving side device. The user cell numbers of all the received user cells are reproduced, the phase difference of the 0/1 system is calculated from the deviation of the user cell numbers of the 0/1 system, and the calculated phase difference corresponds to the calculated phase difference. Corrected by the receiver is a method for performing 0/1 system switching performs phase alignment.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of the present embodiment. FIG. 2 is a diagram showing the relationship between user cells on the transmitting side and user cell numbers. FIG. 3 is an arrangement diagram of user cells mapped to the STM-1 format. FIG. 4 is a diagram showing the relationship between the 0-system and 1-system user cells received by the phase shift detector on the receiving side and the user cell numbers.

In FIG. 1, a user cell number adding section 9 adds a user cell number as shown in FIG. 2 and sends it to both 0/1 dual-system transmission format conversion sections 7 and 8. At the time of conversion to the SDH format in the 0, 1 transmission format converters 7 and 8, the first user cell A of the SDH format is used.
The user cell number a to the section overhead section SOH
To the specified position. This STM-1 signal is 0, 1
It is sent to the system transmission lines 5 and 6.

On the receiving side, first, the 0 and 1 system receiving format converters 3 and 4 receive this, convert the SDH format to full ATM, and at the same time, convert the value of the first user cell number inserted in the SOH into each user cell. The user cell number is reassigned. At this time, the SEL unit 1 does not receive a signal in a reception standby state. In the phase shift detector 2,
The phase shift value is calculated from the shift of the first user cell number of the 0/1 system, and the phase shift value is notified to any of the 0, 1 system receive format converters 3, 4. The reception format conversion unit adjusts the cell transmission into the device by the notified phase shift value so that the phase of the 0/1 system received by the SEL unit 1 matches, and the instantaneous interruption switching is performed here. It is. still,
In this embodiment, the case of STM-1 has been described.
The same can be applied to −N.

[0010]

As described above, the present invention utilizes the user cell number of the user cell, detects the phase difference of the user cell, and constantly adjusts the phase. There is an effect that the 1-system instantaneous interruption switching system can be realized.

[Brief description of the drawings]

FIG. 1 is a block diagram of an embodiment.

FIG. 2 is a diagram illustrating a relationship between a user cell on the transmitting side and a user cell number in FIG. 1;

FIG. 3 is a layout diagram of user cells mapped to STM-1 in FIG. 1;

FIG. 4 is a diagram illustrating a system 0 received by a phase shift detector on the receiving side in FIG.
FIG. 6 is a diagram illustrating a relationship between a system user cell and a user cell number.

[Description of Signs] 1 SEL section 2 Phase shift detection section 3 0 system reception format conversion section 4 1 system reception format conversion section 5, 60, 1 system transmission line 7, 80, 1 system transmission format conversion section 9 user cell Number addition part

Continuation of the front page (72) Inventor Hiroshi Ota 1-6-1 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-4-369140 (JP, A) JP-A-4- 98917 (JP, A) JP-A-4-286242 (JP, A) JP-A-6-164623 (JP, A) IEICE Technical Report CS 92-48 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/28 H04L 12/56 H04L 1/22 JICST file (JOIS)

Claims (1)

(57) [Claims] 1. In a 0/1 system uninterruptible switching system in an ATM communication system based on SDH (New Period Digital Hierarchy), a transmission path transmitting side device transmits a user cell number to a user cell outside a cell in a device. , And the user cell number of the first user cell included in the STM-1 signal is inserted into a part of the overhead of the STM-1 signal and transmitted to the partner station. , The user cell numbers of the first user cell included in the STM-1 signal are restored in each of the 0 and 1 systems, and the user cell numbers of all the received user cells are reproduced. A, wherein a phase difference of the 0/1 system is calculated from the deviation of the user cell number of the above, and the calculated phase difference is corrected by a corresponding receiving unit to perform phase matching and perform 0/1 system switching. 0/1 system instantaneous interruption switching system in TM communication system.