KR20040010930A - apparatus and method of management for ATM Adaptation Layer1 link connection condition Access GateWay - Google Patents

Abstract

PURPOSE: A device for managing an AAL1 link connection state of an access gateway and a method therefor are provided to transmit an alarm state through a time slot of an AAL1 link connected with an E1 framer link in order to propagate an alarm from an E1 framer, thereby implementing alarm propagation. CONSTITUTION: An access gateway(100) comprises as follows. A message control task(150) periodically generates a ping message for checking an AAL1 link state with another access gateway(200), decides whether a message is received from the access gateway(200), sets a connection state of an AAL1 link with the access gateway(200) according to a kind of the message, generates the message, and stores the connection state of the AAL1 link in a database. An HDLC driver(160) converts each message showing the connection state of the AAL1 link in HDLC type, and transmits the converted messages to an AAL1 device(130). An alarm management task(140) reads information on the connection state if being requested to manage an alarm state of the AAL1 device(130), and performs alarm management.

Description

Apparatus and method of management for ATM Adaptation Layer1 link connection condition Access GateWay}

The present invention relates to an apparatus for managing an ATM Adaption Layer 1 (AAL1) link connection state of an access gateway, and more particularly, to a connection state of an AAL1 link between access gateways in an access gateway system connected to each other via an AAL1 link. An apparatus and a method thereof are provided.

1 is a schematic structural diagram of an access gateway connected through an AAL1 link. Referring to FIG. 1, an Access GateWay 2 is connected to a Local Exchanger LE 1 via an E1 link interface. On the other hand, the access gateway 2 is optically connected to another access gateway 3 via an AAL1 link. The access gateway 2 consists of an E1 framer (FR) 2a connected to the E1 link, and an AAL1 2b optically connected via another AAL1 link with another gateway 3.

FIG. 2 shows the access gateways 2 and 3 shown in FIG. 1 in more detail. For convenience, the member numbers of 10 and 20 were used.

Referring to FIG. 2, the access gateway 10 includes an E1 framer 11 connected to an E1 link, an AAL1 device 13 and an E1 framer for optically connecting another gateway 20 with an AAL1 link. (11) or an alarm management task unit 14 for managing an alarm state of the AAL1 device 13 is configured.

The E1 framer 11 performs a function of transmitting and receiving frame data with a local exchange connected through the E1 link.

On the other hand, the AAL1 device 13 performs a function of adapting the frame data of the E1 framer 11 to an ATM cell. In other words, to support various kinds of services with different traffic characteristics and system requirements, it is necessary to adapt different classes of applications to the ATM layer. The AAL1 device 13 performs this function and depends on the type of service.

The AAL1 device 13 supports connection-oriented services that require a constant bit rate and has clear time adjustment and delay requirements. Here, the case is explained using the E1 link using 32 frames.

The alarm management task unit 14 monitors the E1 link state in the E1 framer 11 to declare an alarm state, and monitors the AAL1 device 13 to manage whether an alarm state of the AAL1 link is present.

In the figure, the TDM switch 12 and the HDLC driver 15 are indicated by dotted lines. The reason indicated by the dotted line is to show that in the conventional case, the TDM switch 12 and the HDLC driver 15 are not involved in the alarm management operation. The TDM switch 12 performs switching for frame conversion between the E1 framer 11 and the AAL1 device 13. The HDLC driver 15 performs data conversion by the HDLC protocol in the access gateway 10.

High-Level Data Link Control (HDLC) is a transport protocol used in the data link layer, which is the second layer of the OSI seven-layer model of data communication, and is used within an X.25 packet switching network. In HDLC, data consists of units called frames. The frame is sent over the network, verifying that it arrived successfully at the destination. The HDLC protocol embeds information within the data frame to control data flow and correct errors.

In the conventional system connected with the AAL1 link configured as described above, a method for determining an abnormality of the AAL1 connection may include a receiver cell, a dropped cell, an underrun, a lost cell, There are ways to check counters such as overruns and miss-inserted cells, and to check the AIS (Alarm Indication Signal) that is sent when the opponent is in Loss of Signal. .

However, in the system configured as shown in FIG. 2, there is no method of transmitting an alarm condition generated at the link of the E1 framer 11 to the counterpart 20 connected to each other through the AAL1 device 13.

This is because, in FIG. 2, the alarm condition generated through the E1 link of the local exchange is terminated in the E1 framer 11 and is not transmitted to the AAL1 device 13 through the TDM switch 12.

That is, the structure in which the link of the E1 framer 11 and the link of the AAL1 device 13 are 1: 1 is connected to the E1 signal in a central office termination (COT) system connected to the outside through the AAL1 link. It can be used to send to a Remote Termination (RT) system, but the E1 alarm cannot pass through the TDM switch 12 because it terminates at the framer 11.

Therefore, the alarm management task unit 14 must periodically monitor the AAL1 device 13 to confirm the alarm state of the AAL1 link. If the AAL1 device 10 determines that the receiver is in a loss of signal state, the AAL1 device 10 inserts an AIS cell into the transmitter.

In addition, the method of inserting an AIS cell in the AAL1 device 13 when an alarm is declared in the E1 framer 11 can distinguish whether the actual alarm condition is generated from a link on the AAL1 device 13 or a link on the E1 framer 11. There is no. Accordingly, there is a problem in that the alarm state terminated at the E1 framer 11 cannot be transmitted to the counterpart 20 connected through the AAL1 device 13.

The present invention has been made to solve such a conventional problem, and checks the alarm state between the gateway connected through the AAL1 link, and the alarm state of the E1 framer link through the AAL1 link connected 1: 1 with the link of the E1 framer. An object of the present invention is to provide an AAL1 link connection state management apparatus and a method of propagating an access gateway.

1 is a schematic structural block diagram of an access gateway system having an AAL1 link connection.

2 is a system configuration block diagram for conventionally managing alarms in an access gateway.

3 is a system configuration block diagram for managing alarms in an access gateway in accordance with the present invention.

4 is a conceptual diagram illustrating an AAL1 link connection state management operation of an access gateway according to the present invention.

5 is an AAL1 link connection state management operation flow diagram of an access gateway according to the present invention;

6 is a view for explaining the concept that switching is performed for the E1 alarm alarm propagation operation of the access gateway according to the present invention.

<Description of the symbols for the main parts of the drawings>

100, 200: access gateway 110, 210: E1 framer

120, 220: TDM switch 130, 230: AAL1 device

140, 240: alarm management task unit 150, 250: message control task unit

160, 260: HDLC driver

An AAL1 link connection state management apparatus of an access gateway for achieving this purpose is a system in which an E1 framer and one or more access gateways including an AAL1 device are connected through an AAL1 link. Periodically generate a ping message for checking the AAL1 link status with the way, and determine whether there is a message received from a counterpart access gateway for the ping message, and access according to whether the message is received and the type of the message. Connection of the AAL1 link generated by the message control task unit with the message control task unit for setting the connection state of the AAL1 link between the gateways, generating a corresponding message, and storing the connection state of the set AAL1 link as a database. HDLC displays each message indicating status The HDLC driver converting the data to the AAL1 device and transmitting the connection to the AAL1 device, and when there is a request for managing the alarm state of the AAL1 device, the alarm management is performed by reading the connection state information of the AAL1 link stored in the database of the message control task unit. It is configured to include an alarm management task unit to perform.

In addition, the method for managing an AAL1 link connection state of an access gateway according to the present invention is a method of managing a connection state of an AAL1 link between access gateways in a system in which one or more access gateways are connected through an AAL1 link. Periodically transmitting a ping message for checking the AAL1 link state to a counterpart access gateway connected through the terminal; determining whether there is a message received from the counterpart access gateway with respect to the ping message, and receiving the corresponding message; Setting the connection state of the AAL1 link between the corresponding access gateways according to the type of message, storing the connection state of the set AAL1 link in a database, and if there is a request for managing the AAL1 link connection state, the data The connection status of AAL1 link saved in the base Asserts perform the step of identifying the connection of the link.

Here, in the step of setting the connection state of the AAL1 link between the corresponding access gateway, the connection state of the AAL1 link is divided into a connection loss state, an RDI reception state, and a normal state, a) connection of the current AAL1 link If the state is normal or the RDI reception state, if there is no message received from the partner access gateway until the timer for a predetermined time is released, the connection loss state is set, and b) the connection state of the current AAL1 link is normal. In the case of a status or connection loss state, if the message received until the timer for a predetermined time is released, the RDI reception state is set, and c) the connection state of the current AAL1 link is either connection loss or RDI reception state. In this case, when the received message is a ping message until the timer for a predetermined time is released, the normal state may be set.

The connection status messages of the AAL1 links may be transmitted and received between the access gateways by inserting them into timeslot # 0 of the AAL1 link using the HDLC driver.

In this case, timeslot # 0 of the AAL1 link may include alarm information of an E1 framer.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

3 is a block diagram illustrating a system configuration for managing an alarm in an access gateway according to the present invention. Referring to FIG. 3, an AAL1 link connection state management apparatus of an access gateway according to the present invention includes an E1 framer 110, a TDM switch 120, an AAL1 device 130, an alarm management task unit 140, and message control. It is composed of a task unit 150, HDLC driver 160.

The message control task unit 150 periodically generates a ping message for checking the AAL1 link status with the counterpart access gateway connected through the AAL1 link, and determines whether there is a message received from the counterpart access gateway for the ping message. Determine and set the connection state of the AAL1 link between the access gateways according to whether the message is received and the type of the message, generate the corresponding message accordingly, and store the connection state of the set AAL1 link as a database.

The TDM switch 120 connects with time slot # 0 of the AAL1 link and one channel (64kbps) of the HDLC driver 160. In addition, between the link of the E1 framer 110 and the link of the AAL1 device 130, time slots 1 to 31 except for the time slot # 0 should be 1: 1 in TDM switching. For this purpose, the E1 framer 110 and the AAL1 device 130 must be set to the structure (frame) mode.

The HDLC driver 160 converts each message indicating the connection state of the AAL1 link generated by the message control task unit 150 into HDLC format, inserts time slot # 0, and transmits the message to the AAL1 device 130. The message inserted in time slot # 0 indicates whether an alarm has occurred on the E1 link, whether an alarm has occurred on the AAL1 link, whether the alarm state on the AAL1 link is normal, RDI received, or lost. Information is included.

The alarm management task unit 140 manages an alarm state occurring in a link between the E1 framer 110 and the AAL1 device 130. The message control task unit 150 transmits / receives a message through the HDLC driver 160.

In addition, when there is a request for managing the alarm state of the AAL1 device 130, the alarm management task unit 140 reads the connection state information of the AAL1 link stored in the database of the message control task unit 150. Perform alarm management.

Under the above conditions, the mutual alarm propagation between the E1 framer link and the AAL1 link and the alarm status confirmation on the AAL1 link may be performed.

In the system connected by AAL1 link, the abnormality of AAL1 connection is configured by the time slot # 0 of each link with the HDLC drivers 160 and 260, and transmitted as a message.

Referring to FIG. 4, a transmitter periodically transmits a ping request message, and a receiver sets a timer to declare a connection lost state when there is no ping request message for a given time. Afterwards, it sends a Remote Defect Indication Messgae to the other end.

First, the alarm status checking operation of the AAL1 link will be described.

The message control task unit 150 transmits a ping request message through a HDLC driver 160 using time slot # 0 of the AAL1 link at a 500 msec period. For this to work, the AAL1 link must be set to Structure Mode.

The state of AAL1 El link can be classified into three states: Loss of AAL1 Connection state, Receive RDI state, and Normal state.

First, when there is no message received through the HDLC driver until the 3 sec timer is released in the normal state or the RDI reception state, the corresponding AAL1 link is declared as a connection loss state.

On the other hand, when a message received through the HDLC driver for 3sec in a normal or AAL1 connection loss state is RDI, the corresponding AAL1 link is declared as an RDI reception state.

On the other hand, if a message received through the HDLC driver for 3sec in the connection loss state or the RDI reception state is a ping request, the corresponding AAL1 link is declared normal.

5 illustrates an alarm state checking operation of the AAL1 link. Referring to FIG. 5, the message control task unit 150 polls every 500 msec period (S1). It is determined whether there is a received message transmitted from the counterpart access gateway (S2). If there is no received message, it is determined whether the current alarm setting state for the AAL1 link is a loss state (S3). If the current state is a loss state, the state is set continuously to maintain the current state value (S4).

On the other hand, if the current state is not a loss state, for example, the normal state may be the RDI reception state. In this case, a timer (loss timer) for judging a loss state is operated (S5) and it is determined whether or not the received message exceeds 3 seconds (S6). If there is no received message for more than 3 seconds, set the alarm status to Lost.If there is no received message for more than 3 seconds, if there is a received message, keep the current status. Poll again.

On the other hand, it is determined whether there is a received message (S2) and if there is a received message, it is determined whether the received message is an RDI mesh (S7). If the received message is an RDI message, it is determined whether the current alarm state value is the RDI state (S8). If the current state value is RDI, the current state value is set as it is and maintained as it is (S9). If it is determined whether the current state is RDI and not the RDI state, the timer (RDI timer) for setting the RDI state is operated (S10) to determine whether it exceeds 3 seconds (S11). If the RDI message has been received for more than 3 seconds, set the alarm state to RDI receive. If the RDI message has not been exceeded for 3 seconds, keep the current state. Perform.

On the other hand, it is determined whether the received message is an RDI message (S7), and if the received message is not an RDI message, it is determined whether the current alarm state is normal (S12). If the message has been received, but the message is not an RDI message, it indicates a normal state message. If the current state value is a normal state, the message is set to a normal state as it is (S13). If it is determined that the current state is a normal state, if it is not the normal state, a timer (normal timer) for setting the normal state is operated (S14) to determine whether it exceeds 3 seconds (S14). If the steady-state message is longer than 3 seconds, set the alarm state to normal. If the steady-state message is not exceeded 3 seconds, maintain the current state and poll again. Do this.

Next, the concept of switching for alarm propagation operation will be described with reference to FIG. 6.

The alarm state of the E1 framer link may be propagated through the link of the AAL1 device 130 connected 1: 1 with the link of the E1 framer 110. To propagate the alarm state of the E1 framer link to the opposing system, the E1 framer link and the AAL1 link must be set to structure (frame) mode.

The TDM switch 120 needs to be connected to timeslot # 0 of the AAL1 link and one channel (64kbps) of the HDLC driver 160. In addition, time slots # 1 to 31 except for time slot # 0 between the E1 framer link of the E1 framer 110 and the AAL1 link of the AAL1 device 130 must be TDM switched 1: 1.

This is necessary because time slot # 0 on the E1 framer terminates in the E1 framer and is not forwarded to the AAL1 link even if the E1 framer link is connected 1: 1 through the AAL E1 link and the TDM switch.

That is, time slot # 0 in the E1 framer is a control timeslot for confirming frame connection and is not used as a real payload. Therefore, since time slot # 0 of the AAL1 link cannot be used as a payload, it can be used for alarm propagation.

The operation thereof will be described with reference to FIGS. 3 and 6 as follows.

First, when an alarm occurs in the link of the E1 framer 110, after the E1 frame alarm is declared by the alarm management task unit 140, the corresponding alarm is configured and transmitted through the message control task unit 150.

This message is inserted in TDM switch 120 into time slot # 0 of the AAL1 link. The message control task unit 250 of the opposite end can receive the message and know the alarm state of the E1 framer.

Next, let's take a look at alarm clearing on the E1 framer link.

After the E1 frame alarm is released from the alarm management task unit 140, a corresponding message is configured through the message control task unit 150 to propagate the alarm state.

This message is inserted in TDM switch 120 into time slot # 0 of the AAL1 link. The message control task unit 250 of the opposite end may receive the message to know the alarm state of the E1 framer 110.

On the other hand, when an alarm occurs on the AAL1 link of the AAL1 device 130, the alarm management task unit 140 declares an AAL1 link alarm and transmits an AIS to the corresponding E1 framer 110 link.

In addition, when the alarm is released to the AAL1 link of the AAL1 device 130, the alarm management task unit 140 releases the AAL1 link alarm and stops the AIS sent to the corresponding E1 framer 110 link.

According to the present invention, the following effects can be expected in the implementation of a method using a message for alarm status confirmation and alarm propagation in the AAL1 link.

Therefore, to propagate the alarm in the E1 framer, the alarm status in the E1 framer delivers the relevant message through time slot # 0 of the AAL1 link connected to the corresponding E1 framer link.

First, when the AAL1 link is connected to the E1 framer link via a TDM switch in a 1: 1 manner, alarm propagation is not possible.

In addition, acknowledgment of such alarm propagation and alarm status of the AAL1 link can be used unified in the same message control task.

In addition, this logic is applicable to the AAL1 link used after setting to the framed mode, thereby simplifying task implementation.

Claims (8)

A system in which an E1 framer and one or more access gateways comprising an AAL1 device are connected via an AAL1 link, Periodically generate a ping message for checking the AAL1 link status with the other access gateway connected through the AAL1 link, and determine whether there is a message received from the other access gateway for the ping message; A message control task unit for setting a connection state of the AAL1 link between the access gateways according to the message type, generating a corresponding message, and storing the connection state of the set AAL1 link as a database; An HDLC driver for converting each message representing the connection state of the AAL1 link generated by the message control task unit into an HDLC format and transmitting the converted message to the AAL1 device; If there is a request to manage the alarm state of the AAL1 device, the AAL1 link of the access gateway including an alarm management task unit for performing alarm management by reading the connection status information of the AIL1 link stored in the database of the message control task unit. Connection state management device. The method according to claim 1, wherein the connection state of the AAL1 link set by the message control task unit is divided into a connection loss state, an RDI reception state, and a normal state. a) when the connection state of the current AAL1 link is a normal state or an RDI reception state, if there is no message received from the partner access gateway until the timer for a predetermined time is released, the connection loss state is set; b) when the connection state of the current AAL1 link is in a normal state or a connection loss state, if the received message is RDI until a timer for a predetermined time is released, the RDI reception state is set; c) when the connection status of the current AAL1 link is connection loss or RDI reception, if the received message is a ping message until the timer for a predetermined time is released, the AAL1 link connection of the access gateway set to the normal state; State management device. The method of claim 2, wherein the connection status message of each AAL1 link, An AAL1 link connection state management device of an access gateway that is inserted and received between time gateways # 0 of an AAL1 link using an HDLC driver. The method of claim 1, wherein the message control task unit, When the alarm information of the E1 framer is received from the alarm management task unit, the E1 framer alarm information message is generated accordingly, and the generated message is inserted into timeslot # 0 of the AAL1 link by using an HDLC driver. AAL1 link connection state management device in an access gateway that transmits an alert to propagate an alert. A method for managing the connection state of an AAL1 link between access gateways in a system in which one or more access gateways are connected through an AAL1 link, Periodically transmitting a ping message for checking an AAL1 link state to a counterpart access gateway connected through the AAL1 link; Determining whether there is a message received from a counterpart access gateway with respect to the ping message, and setting a connection state of an AAL1 link between corresponding access gateways according to whether the message is received and the type of the message; Storing the connection state of the established AAL1 link in a database; If there is a request for managing the AAL1 link connection state, reading the connection state of the AAL1 link stored in the database to determine the connection state of the link. The method of claim 5, wherein in setting the connection state of the AAL1 link between the corresponding access gateways, the connection state of the AAL1 link is divided into a connection loss state, an RDI reception state, and a normal state. a) when the connection state of the current AAL1 link is a normal state or an RDI reception state, if there is no message received from the partner access gateway until the timer for a predetermined time is released, the connection loss state is set; b) when the connection state of the current AAL1 link is in a normal state or a connection loss state, if the received message is RDI until a timer for a predetermined time is released, the RDI reception state is set; c) when the connection status of the current AAL1 link is connection loss or RDI reception, if the received message is a ping message until the timer for a predetermined time is released, the AAL1 link connection of the access gateway set to the normal state; State management method. The method of claim 6, wherein the connection status message of each AAL1 link, A method of managing the AAL1 link connection state of an access gateway, which is inserted and received between time gateways # 0 of an AAL1 link using an HDLC driver. The method of claim 5, When receiving the alarm information of the E1 framer connected to the AAL1 link, the E1 framer alarm information message is generated accordingly, and the generated message is inserted into the time slot # 0 of the AAL1 link by using an HDLC driver to the AAL1 link. A method of managing the AAL1 link connection state of an access gateway that transmits and propagates alarms.