JP2002325101A - Packet communication network and its fault detection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a health check function to confirm the normality of a session between an access gateway and an access gateway controller in compliance with the Megaco (Gateway control protocol/Media gateway control protocol). SOLUTION: A health check identifier 'HealthCheck' is specified to a service change method parameter of the service change command of the Megaco. The access gateway 1 periodically transmits a service change command indicating the health check to the access gateway controller 2 and detects the abnormality of a session between them depending on whether or not the access gateway 1 receives an acknowledgement of the service change command indicating the health check within a prescribed time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet communication network and a communication control method therefor, and more particularly to a communication network provided with a communication abnormality detecting means in a packet communication network and an abnormality detection method.

[0002]

BACKGROUND OF THE INVENTION The demand for the Internet is growing rapidly. Communication on the Internet is a de facto standard, the Internet Protocol (IP).
t Protocol, RFC791) and transmission of an IP packet. Networks that use IP technology include intranets, electronic commerce (EC),
It has evolved into various forms such as mobile communication networks.

[0003] With the rapid expansion of the IP-based network, the interconnection and integration of the existing telephone network and the IP-based network have been actively studied. As an interconnection system between the telephone network and the IP-based network, a gateway function is provided by a media gateway (MG) and a media gateway control (MGC: Media Gateway).
An architecture that is distributed among the controllers is under study.

[0004] In the above, the MG performs media conversion, and the MGC controls the MG. By opening the gateway function as a system, scalability is increased and application to a large-scale network becomes possible. The protocol between the MG and the MGC is a gateway control protocol (Gateway) in ITU-T and IETF.
ay control protocol and Megaco protocol are standardized respectively (ITU-TH.248, RFC30).
15).

[0005] Gateway control pro
tocol / Megacoprotocol is transferred on the transport layer (TCP or UDP).
In the specification of the present application, in the following, Gateway con
trol protocol / Megaco prot
ocol is simply described as Megaco.

[0006] On the other hand, there are two methods of connecting a telephone network to an IP-based network: a method using a subscriber line and a method using a common line signaling network. The method using the common channel signal network is as follows.
For connection between the telephone network and the IP-based network, a high-speed interface used as an inter-network connection interface of the ISDN network can be used. Therefore, as a technology for integrating a telephone network and an IP-based network, a method using a common channel signaling network has been receiving attention.

[0007]

When the telephone network and the IP base network are connected by a common channel signaling network, the MGC terminates the common channel signaling network. Therefore, the MGC is required to have a reliability equivalent to that of the conventional exchange, and the MG and the MGC are placed between the MG and the MGC.
A so-called health check function that periodically checks the normality of the session between the server and the server is required. The purpose of the health check is to periodically check the normality of a session and detect a session abnormality early to prevent a call loss due to the session abnormality.

As a means for detecting the above-mentioned session abnormality, there is a method in which the MG monitors non-communication. This is a method of transmitting a control signal to the MGC when the MG has been in a non-communication state for a certain period of time to confirm the session. However, it is difficult to realize the non-communication monitoring function in the MG.

[0009] The health check is performed by M on the transport layer.
In the case of realizing by means other than egaco, it is necessary to establish a session other than Megaco between the MG and the MGC. With this, it is not possible to confirm the normality of the Megaco session between the MG and the MGC. Further, when TCP is applied to the transport layer, two TCP connections (for Megaco and for health check) are required between the MG and the MGC. Therefore, the normality of the MG-MGC session should be confirmed by utilizing Megaco.

However, the currently standardized Megac
o has a problem that there is no health check function.
If a new command for health check is defined in Megaco, it is necessary to extend the protocol specification.

[0011]

In order to solve the above-mentioned problem, a communication abnormality detecting method in a packet communication network according to the present invention realizes a health check function using unused parameters of Megaco.

[0012] Megaco has parameters that allow MGs and MGCs to set mutually understandable values. Generally, the gateway that connects the telephone network and the IP-based network is MG
When the functions are distributed to the MGC and the MGC, one MGC controls one or more MGs. In Megaco, there is a response to a command.

Therefore, in the present invention, an identifier indicating a health check is defined as one of the values that the MG and the MGC can understand each other. The health check function using Megaco according to the present invention is realized by the MG transmitting a command including the health check identifier to the MGC. M
When receiving the command including the health check identifier, the GC transmits a command response to the MG. Commands include:
Use service change (Service Change). Service sent from MG to MGC
Service Ch included in the Change command
Service descriptor of the angle descriptor
The identifier “HealthCheck” for the health check is set in the e Method parameter.

[0014] After establishing a session with the MGC, the MG periodically checks the service Ch for health check.
The first means for transmitting an angle command is provided. Further, the MG includes second means for receiving a response signal from the MGC. When the MG receives a response signal to the health check command by the second means within a predetermined time, the MG
-Judge that the session between MGC is normal. If the MG does not receive a response signal to the health check command from the MGC within a predetermined time, the MG determines that the session with the MGC is abnormal. When the MG detects an abnormality in the session with the MGC, the MG performs a re-establishment process of the MG-MGC session.

According to the present invention, the packet communication network has
And MG2 by using MGaco by periodically checking the MG-MGC session.
-A health check function between MGCs can be realized.

If a health check function is realized in the packet communication network, an MG-MGC session abnormality can be detected at an early stage, and the reliability of MG-MGC communication can be improved.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows an example of a network configuration according to the present invention when the IP network 6 and the public telephone network are interconnected. The public telephone network is, for example, ISUP (ISDN User Part)
And the like, and a circuit switching network 5 for providing a communication path. The access gateway device 1 interconnects the circuit switching network 5 and the IP network 6.
The access gateway device 1 and the access gateway control device 2 are connected by an IP network 3.

The access gateway device 1 has an MG function, and connects a communication line between the circuit switching network 5 and the access gateway device 1 according to an instruction from the access gateway control device 2. In addition, the access gateway device 1
Is a PPP (Point to Point Prot)
ocol) and L2TP (Layer2T)
UNELLING PROTOCOL) function and RAD
IUS (Remote Authentication)
DialIN User Service).

The access gateway control device 2 is configured to
It has a C function and transmits and receives control signals to and from the exchange via the common channel signaling network 4. The communication between the access gateway device 1 and the access gateway control device 2 is Megaco.
Use

FIG. 2 shows the configuration of the access gateway device 1. The access gateway device 1 includes a control unit 11
And the interface unit 13 (13a-13d) and the switch 12 are connected by the bus 14.

The control section 11 includes a program for controlling signals between the access gateway control device 2 and the IP network 6, communication control information, and call information during communication. The control program includes the access gateway device 1 shown in FIG.
And a health check processing routine 30 between the access gateway controller 2 and the access gateway controller 2. Interface unit 13
Is a line 15 to the circuit switching network 5 and a line 16 to the IP network 6.
Is terminated. The switch 12 has a switching function in the access gateway device 1.

FIG. 3 shows a format of a control signal 500 transmitted between the access gateway device 1 and the access gateway control device 2. The control signal 500 is I
It comprises a P header 510, a TCP / UDP header 520, and user data 530. The Megaco message is set in the user data 530. Source port 521 and destination port 522 of TCP / UDP header 520
, A port number used by the access gateway device 1 and the access gateway control device 2 for Megaco is set.

In this embodiment, the health check is performed using Mega.
co's Service Change command. FIG. 4 shows a setting example of the Service Change command. First, the Meg transmitted and received between the access gateway device 1 and the access gateway control device 2
The configuration of the aco message will be described.

The Megaco message has a header 53
1 (531a, 531b) and one or more transactions 532 (532a, 532b). The header section 531 indicates identification information of the message transmission source. Transaction 532 includes one or more actions 533 (5
33a, 533b).

An action 533 includes one or more commands 53 applied to one context (Context).
4 (534a, 534b). Each command is Meg
Manipulate the logical objects that make up the connection model of aco. Context and termination (T
“ermination” is a logical object constituting the Megaco connection model. Cont
ext is a logical object in MG indicating an association between Terminations. Termina
“tion” is a logical object in MG indicating a TDM channel or an RTP flow.

FIG. 4A shows a setting example of a health check Megaco message transmitted from the access gateway apparatus 1 to the access gateway control apparatus 2. The service change is set in the command 534a. The service change command includes a service change descriptor including a plurality of parameters. Service Change Meth of Service Change Descriptor
A value that can be mutually understood between the access gateway device 1 and the access gateway control device 2 can be set in the od parameter. Therefore, in the present invention, a health check identifier “HealthCheck” is defined,
Set to the "Vice Change Method" parameter.

FIG. 4B shows a service for health check.
7 is a setting example of a response message transmitted to the access gateway device 1 by the access gateway control device 2 that has received the ice Change command. The same transaction ID as the transaction 532a is set in the transaction 532b, indicating that the transaction 532b is a response to the transaction 532a. A response to the service change command 534a is set in the command 534b.

FIG. 5 shows a health check processing routine 30 in this embodiment. This routine is started when the access gateway apparatus 1 establishes a Megaco session with the access gateway control apparatus 2.

The access gateway device 1 is shown in FIG.
Service Cha for health check shown in (a)
An nge command is transmitted to the access gateway control device 2, and a health check transmission interval timer and a health check response reception waiting timer are started (step 31).

The health check transmission interval timer specifies a transmission interval of a health check signal transmitted from the access gateway device 1 to the access gateway control device 2. The health check response reception waiting timer is a maximum time for which the access gateway apparatus 1 waits for a health check response signal. The access gateway device 1 receives a health check response signal from the access gateway control device 2 and stops the health check response reception waiting timer.

When the access gateway device 1 receives the health check response signal before the expiration of the health check response reception timer, the access gateway device 1 stops the health check response reception timer (step 3).
2) Analyze the health check response (Step 3)
3). If the analysis result of the health check response is OK,
The access gateway device 1 waits until the health check transmission interval timer expires (step 35). When the health check transmission interval timer expires, the process returns to step 31 and the access gateway device 1 repeats transmission of the health check signal.

If the analysis result of the health check response is NG, the access gateway 1 outputs a log (step 34) and waits for the expiration of the health check transmission interval timer (step 35). When the health check transmission interval timer expires, the process returns to step 31 and the access gateway device 1 repeats transmission of the health check signal.

When the health check transmission interval timer expires before the health check response reception waiting timer expires (steps 36 and 37), the access gateway device 1 resends the health check signal to the access control device 2 and resets the health check transmission interval timer. Start (step 38). Subsequently, the access gateway device 1 returns to Step 32.

If the health check response reception waiting timer expires without receiving a health check response (step 36), the access gateway apparatus 1 detects an error in the Megaco session with the access gateway control apparatus 2 (step 39), and End the routine.

Next, the procedure of the health check process between the access gateway device 1 and the access gateway control device 2 shown in FIG. 1 will be described with reference to the sequences shown in FIGS. 6 and 7 show an example of a sequence in which TCP is applied to transport layer communication between the access gateway device 1 and the access gateway control device 2.
In this sequence example, the access gateway control device 2
Opens the TCP connection passively (Passi
ve Open), and the access gateway device 1
Actively open CP connection (Active
Open).

First, the access gateway device 1 transmits a SYN 51 to the access gateway control device 2,
Request establishment of CP connection. Upon receiving the SYN 51, the access gateway control device 2 checks the connection request to the access gateway device 1 (SYN + SY).
N ACK 52). SYN + SYN ACK
The access gateway apparatus 1 having received 52 receives an acknowledgment (SYN ACK) from the access gateway control apparatus 2.
53) is transmitted. Through steps 51 to 53, a TCP connection is established between the access gateway device 1 and the access gateway control device 2.

Next, the access gateway device 1 establishes a session for transmitting and receiving the Megaco message with the access gateway control device 2. The access gateway device 1 transmits the Service Change 54 to the access gateway control device 2 and requests the establishment of a session. Se used for session establishment
Service Change 54 Service Ch
The Mega Method parameter includes Megaco
Set the value standardized in.

When the access gateway control device 2 receives the session establishment request, the access gateway control device 2
response to service 54 (Service Chan
geReply55) to the access gateway device 1. Through steps 54 to 55, a session is established between the access gateway device 1 and the access gateway control device 2.

Subsequently, the access gateway device 1 activates a health check processing routine 30 shown in FIG.
The access gateway device 1 sends a service check Service Cha to the access gateway control device 2.
n56, and the health check transmission interval timer 6
3 and the health check response reception timer 62 is started.

The access gateway device 1 sends a Service Chan from the access gateway control device 2.
ge56 response (Service Change
Reply 57), the health check response reception timer 62 is stopped. After the expiration of the health check transmission interval timer 63, the access gateway device 1
The service change transmission process for health check is repeated (58 to 61, 64 to 67).

FIG. 7 shows a sequence in which the access gateway device 1 detects a session abnormality. The access gateway device 1 is a service C for health check.
change 71, and starts the health check transmission interval timer 75 and the health check response reception wait timer 74.

It is assumed that before the health check response waiting timer 74 expires, the health check transmission interval timer 75 expires without receiving a health check response. The access gateway device 1 is a Service Change 7
2 is transmitted to the access control gateway controller 2, and the health check transmission interval timer 76 is started.

If the health check transmission interval timer 76 expires without receiving a health check response before the health check response waiting timer 74 expires, the access gateway apparatus 1 transmits a Service Change 73 to the access control gateway control apparatus 2, The health check transmission interval timer 77 is started.

When the health check response waiting timer 74 expires, the access gateway apparatus 1 detects a session abnormality (78), and executes a process for re-establishing a session between the access gateway apparatus 1 and the access gateway control apparatus 2. .

[0045]

As apparent from the above description, according to the present invention, a health check function between an access gateway device and an access gateway control device can be realized without changing the Megaco standard in a packet communication network. By monitoring the session between the access gateway device and the access gateway control device using Megaco, an abnormality in the session can be detected early. Therefore, high reliability of communication between the access gateway device and the access gateway control device can be achieved.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an example of a network configuration for interconnecting an IP network and a public telephone network.

FIG. 2 is a block diagram showing a configuration of an access gateway device.

FIG. 3 is an explanatory diagram of a signal format transmitted and received between an access gateway device and an access gateway control device in one embodiment of the present invention.

FIG. 4 is a diagram showing an example of a Megaco message transmitted and received between an access gateway device and an access gateway control device.

FIG. 5 is a flowchart of a health check processing routine according to the present invention.

FIG. 6 is a signal sequence diagram showing a health check transmission procedure in one embodiment of the present invention.

FIG. 7 is a signal sequence diagram showing session abnormality detection in one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Access gateway apparatus, 2 ... Access gateway control apparatus, 3 ... IP network, 6 ... IP network, 4 ... Common line signal network, 5 ... Circuit switching network.

Continued on the front page (72) Inventor Li Jie, 216 Totsuka-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture F-term in the Hitachi, Ltd. Communication Division 5K030 HD03 MC01 5K051 BB02 CC01 CC02 GG01 HH03

Claims (5)

[Claims] 1. An access gateway device comprising: an access gateway device having communication means for communicating with the access gateway device, wherein the access gateway device has a gateway control protocol (Gat)
a first means for periodically transmitting a signal for health check to the access gateway control device by using any of a control protocol or a megaco protocol, and a second means for receiving a response signal from the access gateway control device. When the access gateway device receives a health check response signal within a certain period of time by the second device, the access gateway device determines that communication between the access gateway device and the access gateway control device is normal,
If the access gateway device does not receive a health check response signal by the second means within a certain time,
A packet communication network for detecting a communication abnormality between an access gateway device and an access gateway control device. 2. The service gateway according to claim 1, wherein the access gateway device includes a health check identifier as the health check signal.
The packet communication network according to claim 1, wherein e) a command is transmitted to the access gateway control device. 3. A packet communication network comprising an access gateway device and an access gateway control device, wherein the access gateway device includes communication means for communicating with the access gateway control device, and the access gateway device includes a Gateway control.
protocol or Megaco protocol
1 means for periodically transmitting a signal for health check to the access gateway control device using
A second means for receiving a response signal from the access gateway control device, wherein the access gateway device receives the response signal of the health check by the second means within a predetermined time, the access gateway device and the access gateway control device The access gateway apparatus determines that the communication between the access gateway apparatus and the access gateway control apparatus is abnormal unless the access gateway apparatus receives a health check response signal by the second means within a predetermined time. Detecting an abnormality in a packet communication network. 4. An access gateway device connected to a packet communication network and provided with a communication means for communicating with an access gateway control device, wherein the access gateway control device includes a Gateway control protocol.
a first means for periodically transmitting a health check signal using ocol or Megaprotocol; and a second means for receiving a response signal from the access gateway control device. When the response signal of the check is received, it is judged that the communication with the access gateway controller is normal, and when the response signal of the health check is not received within a predetermined time, the communication abnormality with the access gateway controller is detected. An access gateway device, comprising: 5. A Serv including an identifier for health check.
The access gateway device according to claim 4, wherein a health check function with the access gateway control device is realized by transmitting an ice change command to the access gateway control device.