KR100277473B1 - How to keep client-server connections on IPIO - Google Patents

Abstract

The present invention relates to an Internet Protocol Over ATM (IPOA) communication method, and more particularly, to a client and a server in an IPOA which checks and automatically recovers a connection error between the IPOA client and an ARP server and the connection state. To maintain the connection between the two.

According to the present invention, after the IPOA client periodically sends an ARP request message to the IPOA server, it checks whether or not the response message is received, changes the IPOA inactive mode when there is no response message, and releases the connection between the existing client servers and the new one. After the connection is established, the initialization process is performed to check whether there is an error between the IPOA client and the ARP server and to check the connection status.

Description

How to keep client-server connections on IPIO

The present invention relates to an Internet Protocol Over ATM (IPOA) communication method, and more particularly, to a client and a server in an IPOA which checks and automatically recovers a connection error between the IPOA client and an ARP server and the connection state. To maintain the connection between the two.

The general standard IPO ATM (Standard IP Over ATM) is a standard defined by the Internet Engineering Task Force (IETF) for accommodating an existing Internet service, IP service, in an ATM network.The message is used by an ATM terminal to obtain an ATM address corresponding to an opposite IP address. The format and procedure for sending and receiving messages are described in Request for Comment (RFC) 1577.

The conventional IP service method uses ARP to obtain a MAC address (Media Access Control Address) corresponding to the IP address of the counterpart terminal, and uses the broadcast function without establishing a connection when ARP request and IP packet transmission.

In contrast, IP services in ATM environments have the following characteristics:

First, since the lower layer address used in the IP layer of the ATM network is not an MAC address but an ATM address, the ATM address of the counterpart terminal is queried from the IP address of the counterpart terminal.

Secondly, Ethernet uses a broadcasting function to perform ARP, but ATM does not basically provide a broadcasting function. Therefore, an ARP server is used and each terminal inquires a corresponding ARP server to know an ATM address of a counterpart terminal.

Third, when Ethernet knows the MAC address of the other terminal, it sends out Ethernet frame as soon as possible, but ATM needs to establish a connection before sending data, so it uses the ATM address obtained by ARP to signal the other terminal. Send an IP packet after establishing a connection.

As shown in FIG. 1, the components of general IPOA communication include an IPOA client 10, a terminal to which data is to be transmitted, an ATM switch 20, and a counterpart terminal 30, which is a terminal to receive data. Including the ARP server 40, the IPOA communication method is as follows.

First, assuming that the IPOA client 10 knows the IP address of the counterpart terminal 30 in advance, and does not know the ATM address of the counterpart terminal 30, but knows the ATM address of the ARP server 40 in advance, the corresponding IPOA client 10 establishes an ATM connection with the ARP server 40 using a signaling protocol. In this case, the connection between the IPOA client 10 and the ARP server 40 is usually performed during client initialization, and the connection is continuously maintained.

When the IPOA client 10 makes an inquiry, that is, an ARP request to the ARP server 40, the ARP server 40 based on the IP address of the counterpart terminal 30 in the corresponding ARP request. ATM address of 30 is found and transmitted to the IPOA client 10.

Accordingly, the IPOA client 10 establishes an ATM connection with the counterpart terminal 30 by a signaling method using the ATM address of the counterpart terminal 30 received from the ARP server 40, and establishes the corresponding ATM connection. The IPOA client 10 and the counterpart terminal 30 may transmit and receive an IP packet, and release the corresponding ATM connection when a set time elapses after the transmission and reception of the IP packet is completed.

As such, the IPOA client 10 establishes a connection with the ARP server 40 at system initialization and transmits an ARP request to the ARP server 40 whenever an address information is required, and receives the result to provide an IP service. Perform the operation for.

That is, the connection between the IPOA client 10 and the ARP server 40 should be maintained continuously. If an error occurs, the IPOA client 10 must be restored as soon as possible so that the IP service can be provided.

However, in the related art, although there is nothing related to setting up a connection existing between the IPOA client and the ARP server, there is no technique for detecting and recovering when an error occurs. Therefore, when an error occurs, the system is turned off and then on. Had to be initialized and restarted.

In order to solve the problems described above, an object of the present invention is to facilitate the provision of IP services on ATM by checking and automatically recovering the connection status between the IPOA client and the ARP server and automatically recovering the connection state. do.

1 is a block diagram illustrating general IPOA communication.

2 is a block diagram showing the configuration of an IPOA protocol according to an embodiment of the present invention.

3 is a flowchart illustrating a method for maintaining a connection between a client and a server in an IPOA according to an embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

10: IPOA Client

20: ATM Switch 30: counterpart terminal

40: ARP Server (Address Resolution Protocol Server)

The method for maintaining a connection between a client and a server in an IPOA according to an embodiment of the present invention for achieving the above object comprises: periodically checking whether a response message is received after transmitting initial registration information in an ARP request message; Determining that the connection and operation state is abnormal when the response message is absent for a predetermined number of transmissions of the ARP request message, and changing to the IPOA inactive mode; Releasing the existing connection and attempting to establish a new connection to determine whether the new connection is normally established; Notifying the operator of the impossibility of restoring the connection when a new connection is not established for a predetermined number of attempts of a new connection; In the case where a new connection is established, the method includes registering an own IP address and an ATM address and performing an initialization process of changing an operation state to an ARP server operation mode.

Alternatively, a reverse ARP request message is used instead of the ARP request message, a reverse response message is used instead of the response message, and the normality of connection and operation is verified by comparing the reverse response message with the address information of the existing ARP server. Characterized in that the process further comprises a. The reverse ARP request message and the reverse response message may be address information of an ARP server.

Hereinafter, with reference to the accompanying drawings will be described as follows.

The components of the IPOA communication according to the embodiment of the present invention are the same as those of the prior art shown in FIG. 1, except that the IPOA client 10 and the ARP server 40 using the message format and procedure described in RFC 1577. We propose the Keep Alive Protocol. That is, while maintaining the format and operation procedure of the message defined in the IPOA standard, it monitors whether the connection operation between the IPOA client 10 and the ARP server 40 is normally performed and recovers the connection in case of an error. The procedure is defined.

As shown in FIG. 2, the IPOA protocol structure includes an IP 51 at an upper side, an ATM signal protocol 52 at a lower side, an ATM Adaptation Layer Type 5 (AAL5) 53, and an interface 54 at the bottom. And a virtual channel manager 56 which internally manages the table 55 for the IP 51 and the address pairs (IP, ATM) of the ATM and the lower virtual channel.

Here, the virtual channel manager 56 manages a Virtual Path Connection Identifier (VPCI) and a Virtual Channel Identifier (VCI). In addition, the settings for the corresponding VPCI and VCI are made by the operator's command in the case of the PVC (Permanent Virtual Channel) and the ATM signal protocol 52 in the case of the Switched Virtual Channel (SVC).

Functions required for the initial implementation of the ARP server 40 includes a registration function by ARP packet processing, an ARP function by ARP packet processing, and a timer aging for managing an active state of the IPOA client 10. ) Function.

The registration function is for a registration process of the IPOA client 10. When the IPOA client 10 establishes a connection to the ARP server 40, the ARP server 40 sets the ARP through the corresponding connection. The request is transmitted to the IPOA client 10. When an ARP response to the ARP request is received, the request is stored in the ARP entry table 55. If the ARP response is not received, the connection is released.

When the ARP function queries the ATM address for the IP address through the ARP request from the IPOA client 10 through the already established connection, the ARP function searches the ARP registration table 55 for the corresponding query. Send a response and notify ARP NAK if it does not exist.

In addition, in the ARP registration table 55 of the ARP server 40 for the timer aging function, there is an aging timer value together with the IP 51 and the address pairs IP and ATM of the ATM, and the timer is the IPOA. It is initialized during the initial registration process of the client 10 and is refreshed every time an ARP packet is transmitted or received to the corresponding connection, the timer value is terminated, and an ARP request is sent to the corresponding connection, and an IP address of the IP 51 and the ATM in the ARP response. If the value of the pair (IP, ATM) is the same as the previous ARP registration table 55, the value of the ARP registration table 55 is maintained, and if the value is changed, the value is reflected in the corresponding ARP registration table 55. If there is no ARP response, the connection is released.

Secondly, the functions required for the initial implementation of the ARP client 10 include the same registration function by ARP packet processing, ARP function by ARP packet processing, and timer aging as well as the management function of the ARP server 40 as described above. It includes more.

The registration function, when the ARP client 10 establishes a connection to the ARP server 40 during the initialization process and receives an ARP request, an ARP response to register its IP and ATM address with the ARP server 40. And performs the response to the ARP request transmitted by the ARP server 40 for the state management of the ARP client 10.

The ARP function may be divided into a case of transmitting an IP packet and a case of receiving an IP packet. Each ARP client 10 operates its own local ARP table 55, which sends an ARP request and response to the ARP server 40 to send an IP packet to an IP address that is not in the local ARP table 55. Through the local ARP table 55, the IP 51 of the receiving side and the value of the address pair (IP, ATM) of the ATM are stored, and the connection is established using the obtained ATM address. In addition, the ARP client 10 receiving the ATM connection also receives the IP packet and responds to the received IP packet, if the local ARP registration table 55 is scarce and does not exist in the registration. Through the ARP request and response with the ARP server 40, it is stored as the registered contents of the corresponding local ARP registration table 55. In addition, in order to store the local ARP registration table 55 of the receiving ARP client, such as to shorten the time required for ARP and to prevent various connection settings, the ATM protocol of the sending ARP client must be stored in the signaling protocol 52 or connected from the sending ARP client. Sending an ARP request after setting the option is optional.

The timer aging function operates a timer to release a connection when there is no flow of an IP data packet for a predetermined time with respect to a connection between two ARP clients, and performs packet packeting until IP packet processing is performed until a lower ATM connection is established. Set to (Packet Discarding).

In addition, the management function is a function of checking the active state of the ARP server 40 at regular intervals in the ARP client 10, the ARP client 10 queries the ARP request for its own IP to the ARP server ( If the connection to the ARP server 40 is released for some reason, the server 40 attempts the connection N times at regular intervals and notifies the ATM client operator.

Next, a method of maintaining a connection between a client and a server in the IPOA according to an embodiment of the present invention will be described with reference to the flowchart of FIG. 3.

The IPOA client 10 establishes a connection with the ARP server 40 using the ARP server information at system initialization. Inquiry of the address of the other terminal by using the corresponding connection, periodically performs the following operation to check the accuracy and integrity of the connection.

The IPOA client 10 periodically transmits its own initial registration information to the ARP server 40 via the ATM switch 20 (step S1). In operation 40, the ATM address of the IPOA client 10 is found on the basis of the IP address of the IPOA client 10 in the corresponding ARP request message, and is loaded in an ARP Reply Message to the corresponding ATM switch 20. The IPOA client 10 transmits the data.

The IPOA client 10 waits for the response message for a predetermined time after transmitting the ARP request message to the ARP server 40, that is, received from the ARP server 40 through the ATM switch 20. In the response message, it is determined whether the IP address and the ATM address which are their own address information can be correctly identified (step S2).

If there is no or incorrect reception of its own IP address and ATM address in the second step S2, the IPOA client 10 increases the number of transmissions of the ARP request message by one (step S3). It is checked whether the increased number of transmissions is equal to or greater than 'N' (step S4). Here, the 'N' has already set the number of transmissions in which an error occurs and the connection state with the ARP server 40 and the operation state of the ARP server 40 may be determined to be abnormal.

If the increased number of transmissions is less than 'N' in the fourth step S4, the process returns to the first step S1, and the IPOA client 10 adds its own initial registration information to the ARP request message. The IPOA client 10 transmits to the ARP server 40 through the ATM switch 20. If the increased number of transmissions is equal to or greater than 'N' in the fourth step S4, the IPOA client 10 transmits the ARP server 40. The connection state and the operation state of the ARP server 40 is determined to be abnormal (step S5).

Accordingly, the IPOA client 10 changes to the IPOA inactive mode, which is the same operating state as the system in which the ARP server 40 does not exist (step S6), and changes the existing information through the ATM switch 20. The connection to the ARP server 40 is released (step S7), and a new connection is attempted and the new connection is established (step S8).

If the new connection is not established in the eighth step S8, the IPOA client 10 increases the number of attempts of the new connection by one (step S9) and checks whether the increased number of attempts is 'M' or more. (Step S10). Here, the 'M' has already set the number of attempts to determine that the ARP server 40 cannot be used because an error such that the connection cannot be recovered.

If the increased number of attempts is less than 'M' in the tenth step (S10), the process returns to the eighth step (S8) and the IPOA client 10 tries to establish a new connection again and the new connection is established. If the increased number of attempts is greater than or equal to 'M' in the tenth step (S10), the IPOA client 10 determines that an error that cannot recover the connection has occurred and notifies the operator. (Step S11).

On the contrary, if a new connection is successfully established in the eighth step S8, the IPOA client 10 registers its own IP address and ATM address in the ARP server 40 and displays the operating state in the ARP server operation mode. After performing an initialization process of changing to, the operation of the first step S1 is performed again (step S12).

On the other hand, if the IP address and ATM address correctly received in the second step (S2), the IPOA client 10 is connected to the ARP server 40 and the operating state of the ARP server 40 It is determined to be normal (step S13).

If it is determined that the operation state of the ARP server 40 is normal by performing the above-described operation, the IPOA client 10 inquires the ATM address of the counterpart terminal 30 from the ARP server 40 and The ATM terminal 20 establishes an ATM connection with the counterpart terminal 30, and the IPOA client 10 and the counterpart terminal 30 can transmit and receive IP packets through the corresponding ATM connection.

In another embodiment of the present invention, an Inverse ARP Request message is used in the connection maintenance protocol instead of the ARP request message of the above-described embodiment, and an Inverse ARP Reply Message is used instead of the response message of the above-described embodiment. In this case, the reverse ARP request message is not the address information of its own but the address information of the ARP server, and the reverse response message is the address information of the ARP server. In addition, the terminal may verify whether the connection is normal and whether the ARP server is normal by comparing address information of the existing ARP server and the corresponding reverse response message.

Next, with reference to Figure 1 for a malfunction in IPOA interoperability and its solution will be described in more detail for a number of cases as follows.

Case 1 is a case in which the IPOA client 40 releases the IPOA client 10 when the IPOA client 10 sends an ARP request from the ARP server 40 after establishing a connection with the ARP server 40. The analyzer is placed between the corresponding IPOA client 10 and the ARP server 40 and measured to analyze the packet format of the ARP request of the data channel after establishing the connection of the signaling protocol, and examine the reason for disconnection of the call release message. Check if it is normally terminated by

In Case 1, when the packet format of the ARP request is incorrect or the information of the desired ARP request is insufficient in the IPOA client 10, the IPOA client 10 cannot proceed with the initialization process anymore, and thus releases the established connection. It is. Therefore, reanalysis is performed on the packet format of the ARP request, and the reanalysis is applied to the ARP server 40 again.

For example, if each field length value of the packet format is coded as '0', the corresponding field should not exist and there should be information on the source IP address area of the ARP request transmitted by the ARP server 40. This should set the IP address of the same IP subnetwork as the IPOA client 10.

In the RFC specification, since the basic function of the ARP server 40 is resolution of the values of the IP 51 and the address pairs (IP, ATM) of the ATM, whether or not the IP address of the AP server 40 is described is described. Although it was determined that the ARP server 40 is not necessarily exposed at the IP level, other specifications describe the necessity. Accordingly, the IPOA client 10 checks the IP address of the ARP server 40, and then releases the connection when there is no information on this or if the IPOA client 10 is an IP address of an IP subnetwork different from itself.

Example 2 establishes a connection between an IPOA client 10 and a third-party ATM switch and an ATM server 40, and then the ARP server 40 sends an ARP request and then sends a response to the ARP request. If not received from (10), the IPOA client 10 checks whether the ARP request has been received, and for this purpose, the ARP request as a result of installing a protocol analyzer in the transmission line from the ATM switch to the corresponding IPOA client 10 for measurement. The ARP server 40 checks that there is no ARP server 40 and installs a protocol analyzer in the transmission line from the ARP server 40 to the ATM switch.

Case 2 is a case where the ATM switch cannot exchange ATM cells for the data channel, which is caused by the processing delay of opening the lower data channel of the ATM switch. Therefore, the ARP server 40 performs a normal operation as a result of transmitting an ARP request 1 second after the connection is established, and for this purpose, it notifies the ATM switch and acknowledges that the modified switch operates normally. . On the basis of the results, the item not described in the RFC, that is, if the ARP server 40 does not receive an ARP response within 1 second after sending an ARP request, adds a function of retransmitting N times at 1 second intervals. If there is no ARP response after the N attempts, the ARP server 40 requests the release of the connection.

On the other hand, in rare cases in the case 2, but the results analyzed by the protocol analyzer is different from that described above, that is, that is, the result measured by installing the protocol analyzer in the transmission line from the ATM switch to the IPOA client 10 and the corresponding ARP As a result of the installation of the protocol analyzer in the transmission line from the server 40 to the ATM switch, it was confirmed that there was an ARP request, and the result of the installation of the protocol analyzer in the transmission line from the IPOA client 10 to the ATM switch. As a result of confirming that there is an ARP response and installing a protocol analyzer in the transmission line from the ATM switch to the corresponding ARP server 40, it is confirmed that there is no ARP response. That is, in the transmission line from the corresponding IPOA client 10 to the ATM switch in general, three cells should appear, but only two cells appear.

In this case, cell loss has occurred in the subscriber module of the ATM switch and can be solved by replacing the corresponding subscriber module.

In case 3, IPOA clients 10 and 30 of different companies establish a connection, and then normally transmit and receive IP packets, and after a certain time, the IPOA client 30 of the third party releases the connection with the ARP server 40 and then again. The connection setting between the third party's IPOA client 30 and the ARP server 40 continues after a connection is made. The transmission line from the third party's IPOA client 30 to the ATM switch 20 and the ATM are maintained. During the transmission line from the switch 20 to the corresponding ARP server 40, each of the protocol analyzers is installed so that the IP address of the ARP server 30 can be transmitted before transmitting a disconnection message between the IPOA client 30 and the ARP server 40 of the third party. Make sure to send an ARP request for.

Case 3 is not in the RFC specification, and the third party's IPOA client 30 checks the ARP server 40's active state. The third party's IPOA client 30 requests an ARP request for the IP of the ARP server 40. It is determined to transmit. In addition, a similar function is implemented in the IPOA client 10 so that the ARP server responds to the ARP request of the IPOA client 30 of a third party, and no disconnection occurs.

In case 4, after the third party IPOA client 30 establishes a connection with the ARP server 40, the ARP server 40 normally registers the values of the IP 51 and the ATM address pairs (IP and ATM). When the IPOA client 30 attempts to transmit an IP packet from the IPOA client 10, even the ATM connection is not established. The transmission line or the ATM switch 20 from the IPOA client 30 of the third party to the ATM switch 20. In the transmission line to the corresponding ARP server 40, a protocol analyzer is installed to confirm that there is no ARP request transmission for transmitting an IP packet and periodically sends an ARP request to the ARP server 40.

In case 4 of the third-party IPOA client 30, when the local ARP registration table is viewed, the management table for the ARP server 40 and the management table for other IPOA clients are separated. Registration with the server 40 is insufficient. According to the RFC specification, the ARP request is transmitted by the ARP server 40. However, in case 4, the IPOA client 10 transmits the IP address of the third party as a result of the ARP server 40 responding to the corresponding ARP request. It is set in the local ARP registration table of the client 30 and can communicate an IP packet with the ARP server 40. Accordingly, third-party IPOA clients 30 exchange ARP packets with the ARP server, thereby storing values of the IP 51 of the ARP server 40 and the address pairs (IP, ATM) of the ATM in the local ARP registration table. Perform the action.

Meanwhile, after solving the case 4, IP packet transmission from the IPOA client 30 of the third party to the IPOA client 10 is successfully performed, but the relative registration contents of the local ARP registration table of the two clients 10 and 30 When the IP packet is transmitted from the IPOA client 10 to the terminal of the IPOA client 30 of the third party, the ATM connection is set, but the IP packet is not transmitted. Therefore, the IPOA client 10 cannot transmit or receive the IP packet. Exchanges the ARP packet with the ARP server 40 and checks the ATM connection setting to the IPOA client 30 of the third party and confirms that the IP packet is normally transmitted until the initial IP packet transmission. If a protocol analyzer is installed and measured in the transmission line from the IPOA client 30 of the third party to the ATM switch 20 or the transmission line from the ATM switch 20 to the IPOA client 10, the ARP request is transmitted to the IPOA client 10. Check it. The IPOA client 10 basically sends an ARP response to the ARP request to the ARP server 40.

Even in this case, the registration of the sending IPOA client is not registered in the local ARP registration table of the third party, and the registration in the corresponding local ARP registration table may be made as an ARP response. Therefore, the ARP response to the ARP request of the IPOA client 10 is changed to be transmitted to the corresponding connection, so that the ARP server 40 can be redesigned to process the ARP request from the ARP server 40 and the ARP request from another IPOA client. do. As a result, the sending ARP client is registered in the local ARP registration table of the third-party IPOA client, and IP packet transmission and reception are performed.

In other words, due to the cases described above, the IPOA needs additional functions.

In addition to the functions required for the initial implementation of the ARP server 40, as described in Cases 1 and 3, the information about the ARP packet is accurately implemented and an IP address for the ARP server 40 is allocated. That is, in the initial registration function of the ARP server 40, the value of the IP 51 and the address pairs (IP, ATM) of the ATM for the ARP server 40 is stored so that the IPOA client of the third party is in the state of the ARP server 40. Respond to management. As described in Case 2, the ARP request is initiated N times after establishing the connection from the IPOA client 10 to support reliable IPOA operation. In addition, the ARP response to the ARP request to store the registration details of the IP 51 and ATM address pairs (IP, ATM) of the ARP server 40 in the local ARP registration table of the third-party IPOA client Add

Secondly, a function additionally required for the function required for the initial implementation of the IPOA client 10 is a processing function for the ARP packet as described in the case 4, and initially, the response to the ARP request must be ARP server (40). If an ARP request is received from another IPOA client, the ARP response is sent to the connection.

As described above, according to the present invention, after the IPOA client periodically sends an ARP request message to the IPOA server, the IPOA client checks whether a response message is received and changes to the IPOA inactive mode when there is no response message. By releasing the service and setting up a new connection, the initialization process is performed to check whether there is an error between the IPOA client and the ARP server and to check the connection status.

Claims (9)

Periodically checking whether a response message is received after transmitting initial registration information in an ARP request message; Determining that the connection and operation state is abnormal when the response message is absent for a predetermined number of transmissions of the ARP request message, and changing to the IPOA inactive mode; Releasing the existing connection and attempting to establish a new connection to determine whether the new connection is normally established; Notifying the operator of the impossibility of restoring the connection when a new connection is not established for a predetermined number of attempts of a new connection; A method of maintaining a connection between a client and a server in the IPOA, comprising registering an own IP address and an ATM address when a new connection is established and performing an initialization process of changing an operation state to an ARP server operation mode. . The method of claim 1, A process of using a reverse ARP request message instead of the ARP request message and using a reverse response message instead of the response message, and comparing the corresponding reverse response message with the address information of the existing ARP server, further verifying the normality of connection and operation. Method of maintaining a connection between the client and the server in the IPOA, characterized in that made. The method of claim 2, And the reverse ARP request message and the reverse response message are address information of an ARP server. The method of claim 1, The process of releasing the connection when the client checks the IP address of the ARP server immediately after establishing the connection from the client to the server, and the client does not have information on the IP address or receives an IP address of another IP subnetwork. How to maintain a connection between the client and the server in the IPOA, characterized in that further comprises a. The method of claim 1, If there is no ARP response message from the client, the subscriber module of the ATM switch further comprises the step of identifying the cell loss and replacing the subscriber module. The method of claim 1, When the connection between the client and the server repeats the establishment and release, the server further sends an ARP response message to the ARP request message of the client and does not cause the release of the connection, characterized in that further comprises How to maintain client-server connectivity in IPOA. The method of claim 1, If the third-party client fails to send and receive IP packets after establishing a connection between the third-party client and the server, the third-party client sends and receives the ARP packet with the server and stores the IP and ATM address pair information of the server in the local ARP registration table. Method of maintaining a connection between the client and the server in the IPOA, characterized in that further comprises. The method of claim 7, wherein If it is unable to send and receive the IP packet after establishing a connection between the client and the server of the other company, the ARP response message for the ARP request message of one client is changed to be transmitted to the corresponding connection, so that it is different from the ARP request message authorized by the server. And redesigning each of the ARP request messages authorized by the client. The method of claim 8, The method of maintaining a connection between a client and a server in IPOA, wherein the transmitting client is registered in the local ARP registration table of the client of the third party and the IP packet is transmitted and received.