KR100448711B1 - Optical link aggregation device, and SDH transfer system including the device - Google Patents

Abstract

The present invention relates to a synchronous digital layer (SDH: Synchronous) that connects a synchronous transfer mode (STM) optical link between a digital subscriber line access multiplexor (DSLAM) and a network access server (NAS). Digital Hierarchy) transmission system.

The synchronous digital layer transmission system according to the present invention receives a plurality of STM-1 channels from multiple modem concentrators, bundles two STM-1 channels with the same output path, and focuses on one STM-1 channel for output. And an optical link focusing device. The optical link concentrator is connected to a user-network interface unit that receives a plurality of STM-1 channels and extracts ATM data from each STM-1 channel, and is connected to the user-network interface unit via Utopia 2 to provide the ATM data. Among the traffic manager which determines the output path, the switch fabric which receives ATM data and its output path information from the traffic manager and switches each ATM data through Utopia 2 according to the output path, and among the ATM data input from the switch fabric. It includes a secondary add / drop multiplexer that focuses two ATM traffics with the same output path and outputs them to one STM-1 channel.

Description

Optical link aggregation device and synchronous digital layer transmission system having same {Optical link aggregation device, and SDH transfer system including the device}

The present invention relates to an Internet access system, and more particularly, to a synchronous transfer mode (STM) optical connection between a digital subscriber line access multiplexor (DSLAM) and a network access server (NAS). The present invention relates to a synchronous digital layer (SDH) transmission system for connecting a link.

Recently, the environment of the information and communication market has changed and the paradigm shift is accelerating at home and abroad. Only a few years ago, the voice communication through the wired network occupied the majority, but now the use of Internet service has exploded. Increasingly, there is a demand for the development of an Internet access system to meet this growing demand for Internet services.

1 is a block diagram illustrating an Internet access system for connecting a plurality of subscriber stations to the Internet.

The modem 12 is connected to the subscriber terminal 11 to support the Internet access service, and the modem concentrator (DSLAM) 13 connected to the multiple modems 12 and the multiple subscriber lines to multiplex the data. And an SDH transmission system 14 for converting the data focused in the modem concentrator 13 into an STM-1 level optical link, and a network connection server 15 for connecting the optical link to the Internet 16. .

The SDH transmission system 14 is capable of transferring low-speed data such as E1 (2.048 Mbps), T1 (1.544 Mbps), and DS (344,736 kbps) at high speed STM-N (N = 1, 4, 16, ...) level. The optical signal is multiplexed and transmitted using a time division multiplex (TDM) method. The SDH transmission system 14 maps data of a lower level to an upper level based on STM-1 (155.52 Mbps). It is composed of point-to-point or ring structure and transmitted. The modem concentrator (DSLAM) 13 is connected to the network access server (NAS) 15 via the SDH transmission system 14 using the STM-1 optical link.

In the case of a modem concentrator (DSLAM) using ATM data, this ATM data must also be carried on the STM-1 optical link, and the STM-1 optical link with ATM data occupies only 50% of the total bandwidth of the STM-1. The remaining 50% of the capacity is wasted.

Referring to FIG. 2 in detail, the SDH transmission system 22 which attempts to connect a number (N) of modem concentrators (MDSLAM: Multi-DSLAM) 21 to a network access server (NAS) 23 is provided. In addition, N x STM-1 input / output transmission bandwidths are required. In the case of the output transmission bandwidth of the SDH transmission system, one channel is allocated to each modem concentrator and each channel is used only 50% of the total capacity, so the remaining 50% of the capacity is wasted.

That is, 2728 connections can be configured per STM-1 channel, but the STM-1 flowing into the SDH transmission system from the modem concentrator is composed of only 1364 connections per channel. In this case, since the STM-1 channel connected to the NAS in the SDH transmission system is connected to each modem concentrator (DSLAM), 50% of the total transmission capacity is used for data transmission, but the remaining 50% is wasted.

An object of the present invention is to aggregate two STM-1 channels input from two modem concentrators (DSLAM) into one STM-1 channel and output them to the NAS, thereby reducing ATM traffic without wasting resources. The quality of service is to provide an optical link focusing apparatus which can guarantee and a synchronous digital layer transmission system having the same.

The optical link focusing apparatus of the present invention for achieving the above object, the user-network interface unit for receiving a plurality of STM-1 channels to extract ATM data from the STM-1 channel, the user-network interface unit and utopia A traffic manager connected through 2 to determine an output path of the ATM data, and receives ATM data and output path information of the ATM data from the traffic manager, and switches the ATM data through Utopia 2 according to the output path. And a secondary ad / drop multiplexer for converging two ATM traffic having the same output path among the ATM data inputted from the switch fabric and outputting the same to one STM-1 channel.

In addition, the synchronous digital layer transmission system according to the present invention is connected between a plurality of modem concentrator (multi-DSLAM) and a network access server (NAS), a plurality of inflow from the plurality of modem concentrator (multi-DSLAM) Transmits the STM-1 channel to the network access server (NAS) to provide Internet access services to a plurality of subscriber stations connected to the plurality of modem concentrators, and a plurality of STM- streams from the plurality of modem concentrators. An optical link concentrator that receives one channel and bundles two STM-1 channels with the same output path, focuses them on one STM-1 channel, and performs add / drop / pass-through operation on the focused STM-1 channel. And an add / drop control unit (ADCU) for controlling and a low voltage digital signaling (LVDS) interface unit for matching between the optical link focusing device and the ADCU.

1 is a block diagram showing an Internet access system for connecting a plurality of subscriber terminals to the Internet;

2 is a view illustrating a problem of the prior art;

3 is a block diagram of an Internet access system constructed using an optical link focusing apparatus and a synchronous digital layer transmission system according to the present invention;

4 is an internal configuration diagram of an optical link focusing apparatus according to an embodiment of the present invention.

※ Explanation of code about main part of drawing ※

40: optical link focusing device 41: user-network interface unit

42: Traffic Manager 43: Switch Fabric

44: interface unit 45: auxiliary add / drop multiplexer

50: SDH transmission system 51: ADCU

52: LVDS interface unit

Hereinafter, an optical link focusing apparatus and a synchronous digital layer transmission system including the same according to the present invention will be described with reference to the accompanying drawings.

3 is a block diagram showing a part of the Internet access system according to the present invention.

An optical link concentrator 31 is mounted at an input of an SDH transmission system 30 connected between a plurality of modem concentrators (multi-DSLAM) 21 and a network access server (NAS) 23. The optical link concentrator 31 concentrates two STM-1 channels of the STM-1 channels flowing from the plurality of modem concentrators 21 into one STM-1 channel and then performs an operation of the SDH transmission system 30. Send to ADCU (Add / Drop Control Unit) not shown.

ATM data of modem focusing device basically supports unspecified bit rate (UBR) service. Data flowing from the plurality of modem concentrators 21 into the optical link concentrator 31 may constitute 1364 connections per STM-1 channel, and the optical link concentrator 31 focuses two channels. Configure 2728 connections per channel. Here, when 10 connections are allocated to a constant bit rate (hereinafter referred to as CBR) service, 2718 connections may support the UBR service.

4 is an internal configuration diagram of an optical link focusing apparatus 40 according to an embodiment of the present invention.

The optical link concentrator 40 includes a user to network interface (UNI) 41, a traffic manager 42, a switch fabric 43, and a switch fabric 43. And an auxiliary add / drop multiplexer (TADM) 45 and an interface unit 44 for matching the switch fabric 43 and the auxiliary add / drop multiplexer 45. One user-network interface unit 41 may receive up to two STM-1 channels from up to two modem concentrators, and up to two user-network interfaces 41 may be connected to the traffic manager 42. Do. In addition, up to two traffic managers 42 may be connected to the switch fabric 43. The switch fabric 43 has 8x8 channels and supports 155Mbps per channel, a total of 1.2Gbps. Accordingly, the optical link concentrator 40 receives STM-1 channels from up to eight modem concentrators, and focuses two STM-1 channels with the same path to the SDH transmission system 50. .

The user-network interface unit 41 receives two STM-1 (155.520 Mbps) upper link channels from a plurality of modem concentrators 21, extracts a clock, and extracts ATM data from SDH frames of each STM-1. It performs header error control (HEC).

The traffic manager 42 is connected to the user-network interface unit 41 and the UTOPIA2 Universal Test Operations PHY Interface for ATM-level 2 (UTOPIA2), and extracts the extracted ATM data for each service class (CBR, VBR (variable bit). UPC (usager parameter control), parsing (policing), and shaping are performed for each rate (ABR), available bit rate (ABR), and UBR. That is, the traffic manager 42 determines the service class of the subscriber, and determines the maximum cell rate (PCR), the CDV allowance (Cell Delay Variation Tolerance), the average cell rate (SCR), and the minimum for each service class. It sets and controls parameters such as MCR (Minimum Cell Rate). When data over the specified value is received, the corresponding cell is discarded according to the priority.

The switch fabric 43 switches and outputs the ATM traffic transmitted through the traffic manager 42 through Utopia 2 along the path.

The auxiliary add / drop multiplexer 45 receives ATM traffic from the switch fabric 43 through Utopia 2, bundles two ATM traffics having the same path, and forms a single SDH frame, thereby converting the ADCU of the SDH transmission system 50 into 51). The auxiliary add / drop multiplexer 45 and the ADCU 51 are matched through a low voltage digital signaling (LVDS) interface 52. The optical link focusing device 40 may be mounted as a subscriber card inside the SDH transmission system 50 or may be connected to a separate external device.

Referring to the operation of the optical link focusing device 40 configured as described above is as follows.

In case of an upper link transmitted from a plurality of modem concentrators (Multi-DSLAM) to a network access server (NAS), the user-network interface unit 41 receives an STM-1 channel from each modem concentrator and receives an STM-1 channel. Extracts ATM data from the SDH frame and passes the ATM data to the traffic manager 42. Up to two STM-1 channels are input to one user-network interface unit 41.

The traffic manager 42 interprets the virtual path information and the virtual channel information stored in the header of the ATM data, sets the path of the corresponding ATM data, and connects one-to-one to each terminal of the switch fabric 43. Thus, each ATM data is switched for each path. In addition, the traffic manager 42 determines a service class of the received ATM data and sets and controls user parameters for each service class. When data of more than a predetermined value is received, the traffic manager 42 corresponds to the priority of the corresponding ATM data. Discard the ATM cell.

The switch fabric 43 switches ATM data along a path and delivers it to the auxiliary add / drop multiplexer 45 through the interface unit 44. The auxiliary add / drop multiplexer 45 focuses two input ATM data for each path, generates the SDH frame, and provides it to the SDH transmission system 50. The SDH transmission system 50 receives the STM-1 channel focused by two channels from the optical link focusing device 40 through the LVDS interface unit 52 to the ADCU 51 and adds / drops the respective channels ( Control drop / pass through.

The lower link transmitted from the network access server (NAS) to the multiple modem concentrators (Multi-DSLAM) operates in the reverse order of the upper link described above. That is, the auxiliary add / drop multiplexer 45 separates and extracts two ATM data into SDH frames inputted as one group, and the switch fabric 43 switches each ATM data for each path, and the user-network interface unit 41 ) Converts each separated ATM data into STM-1 channel and transmits it to the corresponding modem concentrator (DSLAM).

As described above, according to the present invention, it is possible to more efficiently use the constant bandwidth allocated when transmitting ATM traffic, thereby ensuring the quality of service without wasting traffic resources.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art will be variously modified and changed within the scope of the invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (4)

In the optical link focusing apparatus that receives a plurality of STM-1 channels and focuses and outputs two STM-1 channels having the same output path, A user-network interface unit receiving the plurality of STM-1 channels and extracting ATM data from the STM-1 channels; A traffic manager connected to the user-network interface unit through a utopia 2 to determine an output path of the ATM data; A switch fabric which receives ATM data and output path information of the ATM data from the traffic manager and switches the ATM data through Utopia 2 according to the output path; And an auxiliary add / drop multiplexer for condensing two ATM traffics having the same output path among the ATM data inputted from the switch fabric and outputting them to one STM-1 channel. The optical link concentrator of claim 1, further comprising an interface unit for matching between the switch fabric and the auxiliary add / drop multiplexer. A plurality of STM-1 channels connected between a plurality of modem concentrators (multi-DSLAM) and a network access server (NAS) and flowing from the plurality of modem concentrators (multi-DSLAM) are connected to the network access server (NAS). In the synchronous digital layer transmission system for transmitting an Internet connection service to a plurality of subscriber terminals connected to the plurality of module focusing apparatus, An optical link focusing device which receives a plurality of STM-1 channels flowing from the plurality of modem focusing devices, bundles two STM-1 channels with the same output path, focuses on one STM-1 channel, and outputs them; An add / drop control unit (ADCU) for controlling add / drop / passthrough of the focused STM-1 channel; And a low voltage digital signaling (LVDS) interface unit for matching between the optical link concentrator and the ADCU. The optical link focusing apparatus of claim 3, wherein A user-network interface unit receiving the plurality of STM-1 channels and extracting ATM data from the STM-1 channels; A traffic manager connected to the user-network interface unit through a utopia 2 to determine an output path of the ATM data; A switch fabric which receives ATM data and output path information of the ATM data from the traffic manager and switches the ATM data through Utopia 2 according to the output path; And an auxiliary add / drop multiplexer for condensing two ATM traffics having the same output path among the ATM data inputted from the switch fabric and outputting them to one STM-1 channel.