JP2002314595A - Communication repeater and jitter suppression method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication repeater and a jitter suppression method that can suppress jitter (change in delay) caused when the communication repeater transfers real time data (video and audio or the like) employing the RTP(rapid transport protocol) in a packet communication system and can suppress jitter (change in delay) when each transfer frame reaches a destination terminal. SOLUTION: The communication repeater is configured such that the repeater extracts a frame sequence number, a UDP(user datagram protocol) port number and time stamp information of the RTP frame from in-header information of the RTP frame received from an upper-stream communication unit, detects/ outputs a difference from the time stamp information of the just preceding frame, detects/outputs a difference between the just preceding RTP frame reception time and a current time obtained from an internal timer, compares the internal timer difference with the time difference output, and decides the priority of transfer processing to suppress jitter in the data stream of the frame on the basis of the difference (jitter).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an RTP (Rapid Tr
ansport Protocol) and UDP (User Datagram Prot)
OTC), a communication relay apparatus and a jitter suppression method for suppressing jitter (delay change) for each transfer frame in a data transfer path, and a method for transferring the real-time data (image, voice, etc.) About.

[0002]

2. Description of the Related Art In the case of performing image, voice or simultaneous communication using a packet communication line, communication using a communication protocol; RTP (Rapid Transport Protocol) and UDP (User Datagram Protocol) is generally performed.

Generally, in this type of communication, for example, in a communication system shown in a schematic block diagram in FIG. 4, a transmitting terminal device 20 captures an image to be transmitted by an image input unit 21 and converts this image signal into an image encoding unit 22. Is converted into information that has been subjected to compression, encoding, and the like appropriate for communication, and this information is passed to the transmission unit 23.

[0006] In order to transmit image information to the receiving terminal 4 using the RTP protocol, the transmitting unit 23
The P packet assembling section (not explicitly shown) adds an information such as a necessary header to the image information to generate an RTP packet. The generated RTP packet is provided with information such as a header in a UDP packet
A packet is generated. The generated UDP packet is
The packet is transmitted to an appropriate packet communication line 30 from a packet transmitting unit (not specified).

[0005] For example, a packet communication line 30 such as the Internet or the like generally includes a plurality of communication relay devices (routers and the like), and UDP packets pass through these communication relay devices via a predetermined route through the receiving terminal device 40. Transported to

[0006] In the receiving terminal device 40, the packet arriving via the packet communication line 30 is received by the receiving unit 41. In the receiving unit 41, first, the packet receiving unit (not specified) receives a packet from the communication line. Next, UDP
An RTP packet is extracted from the received UDP packet by a packet disassembly unit (not specified). Further, only the image information portion is extracted from the RTP packet extracted by the RTP packet decomposing unit (not specified), and
In step 2, data is restored by decoding and decompression, and an image signal is output from the image output unit 43.

As described above, the image information to be transmitted is represented by RTP
The packet is placed on the packet, and the RTP packet is placed on the UDP packet, and the transmission on the packet communication line is performed. Note that UDP (User Datagram Protocol) is a protocol that emphasizes high-speed transmission over reliability. U
In the DP, transmission of a high throughput can be performed only by sending a packet to a partner terminal and without performing other processing such as retransmission. In addition, RTP (Rapid Transport Protocol) is used as a higher-level protocol for transporting real-time data.
, And the protocol supports packet sequence numbers and time stamp information.

FIG. 5 shows an example of the configuration of an RTP packet. An RTP packet is composed of a header and a payload. The header includes an RTP version number a, a payload type c for identifying the type of data, a time stamp e indicating the data display time, and other areas. The payload is, for example, S defined in MPEG-4.
It consists of L packets. Payload must be 1 by regulation
Contains one packet. By the way, when real-time data (images, voices, etc.) are converted into IP packets and conveyed over a LAN network, the Internet, or the like, a significant effect is caused by the time (delay) to reach the receiving terminal and its jitter ( Change in delay).

In order to suppress the delay itself, a technique for preferentially processing the above-described IP packet by individual routers constituting a packet communication line such as a LAN has already existed and has been put to practical use. If the IP packet jitter occurs due to the interposition of a router that does not have the priority processing function, it may not be possible to absorb the jitter even with a router that supports the same priority processing technology. .

In the RTP protocol, the status of jitter between the transmitting terminal and the receiving terminal of the frame (IP frame [RTP as upper layer protocol]) is reported based on the sequence number and time stamp information of the packet to be supported. RTCP (RTP Con
trol Protocol).
Using the information on the jitter reported by the protocol, it is possible to change the packet to be preferentially transferred by increasing the bandwidth or the like.

However, since it is not the jitter suppression control based on the packet itself, it is difficult to follow in near real time, and since the control point is between terminals, the jitter generated in each area in the network in the middle is sufficiently absorbed. It is also difficult.

As a countermeasure against jitter on the receiving terminal side, for example, JP-A-2000-92130 (clock fluctuation compensation method and real-time audio /
The visual system is a client (receiving terminal) transmitted over a network with respect to a real-time audio / visual system for transmitting a plurality of data packets including time stamp data and encoded A / V data. Discloses a method for compensating for clock fluctuations in received data packets.

The above publication discloses a real-time audio system for transmitting a plurality of data packets including time stamp data and encoded A / V data to at least one client at a substantially fixed bit rate via a network. As a method for compensating clock fluctuation of a visual system, a client temporarily stores a received data packet in a first buffer, and generates a clock generated in the client and time stamp data included in the selected data packet. And outputs the selected data packet from the first buffer and supplies it to the second buffer at a time scheduled based on the result.
And the like, in which data packets stored in the buffer are supplied to a data decoding device of the client.

According to the publication, the client uses A / V
A transmission packet transmitted via a network including jitter is sequentially received from a server that encodes and packetizes a stream, and jitter is removed by a jitter removal buffer using a time stamp of each transmission packet and a decoding clock of the client itself. . At the scheduled time, each data packet is output to the synchronization buffer and supplied to the A / V decoding device according to the speed of the A / V stream. At this time, the clock synchronization between the client and the server is performed by monitoring the position of the synchronization buffer using the half position of the synchronization buffer as a reference position.

In the case of the above technique, since the control point is the terminal device itself, when excessive jitter occurs in each area in the network on the way, it cannot be said that there is no situation where the jitter cannot be absorbed as expected. There may be situations where it is essential to use the jitter suppression means in the transmission path.

[0016]

As described above, in the transfer of real-time data, the jitter generated in each area in the network with respect to the IP packet [RTP as an upper layer protocol] that carries the data is expressed by:
There is a need for a technique for absorbing in real time in a relay node such as a router configuring each area, and as a result, suppressing jitter between transmission and reception terminal devices (constant delay).

Accordingly, the present invention provides a method of RTP (Rapid Transp.
Ort Protocol) when transferring real-time data (images, audio, etc.) with a communication
It is a technical object to suppress delay (change in delay) and to suppress jitter (change in delay) upon arrival at a destination terminal device for each transfer frame.

[0018]

According to the first aspect of the present invention, at least a communication protocol;
TP (Rapid Transport Protocol) and UDP (User
A communication relay device in a communication network performing packet communication using Datagram Protocol extracts a frame sequence number, a UDP port number, and time stamp information of the RTP frame from information in a header of the RTP frame received from the upstream communication device. A UDP / RTP header detection unit, and a U-port having the same UDP port number extracted this time
If there is a previously received RTP frame having a DP port number, a difference between the sequence number of the UDP frame and the stored frame sequence number of the immediately preceding RTP frame is detected, and the difference detection result is set in advance. If the difference is equal to or less than the predetermined value, the difference between the stored time stamp information of the immediately preceding frame and the time stamp information extracted from the current reception frame is detected and output, and the time stamp information extracted from the current reception frame is detected. And a time stamp difference detector that writes and stores the same UDP port number in the external memory at a predetermined position corresponding to the extracted UDP port number, and a previously received RTP having the same UDP port number as the currently extracted UDP port number. If there is a frame, the sequence number of the UDP frame The difference between the stored last RTP frame and the frame sequence number of the immediately preceding RTP frame is detected. If the difference detection result is equal to or less than a predetermined value, the difference is obtained from the stored immediately preceding RTP frame reception time and the internal timer. An internal timer difference detector for detecting and outputting a difference from the current time value and writing and storing the current time value as a current RTP frame reception time at a predetermined position corresponding to the extracted UDP port number on an external memory; A jitter detector that compares output values of the internal timer difference detector and the time stamp difference detector and outputs a difference between the values, and suppresses a jitter of a data stream related to the frame by an output of the jitter detector. And a packet transmission unit that determines the priority of the transfer processing in the own communication relay device.

According to a second aspect of the present invention, in the communication relay apparatus of the first aspect, when the signal received from the jitter detecting section has a negative value, the packet transmitting section preferentially transmits the frame. The control is performed so as to increase the degree, and if the value is not a negative value, the control is performed so that a delay time is appropriately added.

According to the third aspect of the present invention, the communication relay device is further provided when the detection result of the difference between the sequence number of the frame and the previous frame sequence number is larger than a predetermined value. In the time stamp difference detector, only the process of writing and storing the time stamp information extracted from the currently received frame at a predetermined position on the external memory corresponding to the extracted UDP port number is performed, The detector performs only the process of writing and storing the current time value as the current RTP frame reception time at a predetermined position corresponding to the extracted UDP port number on the external memory, and the jitter detector does not perform the process. To be configured. According to the fourth aspect of the present invention, each of the communication relay devices is configured to further include a packet queue that stores packets for each path and that is output-controlled by the packet transmitting unit.

According to a fifth aspect of the present invention, there is provided a method for suppressing jitter of an RTP packet in a communication relay device in a communication network which performs packet communication using at least a communication protocol; RTP and UDP, wherein the jitter is received from an upstream communication device. Extracts the frame sequence number, UDP port number, and time stamp information of the frame from the information in the header of the RTP frame, and suppresses the jitter of the data stream of the frame based on the frame sequence number, UDP port number, and time stamp information. To change the priority of the transfer process in the own communication relay device.

According to a sixth aspect of the present invention, in the method of the fifth aspect, the same UDP port number as the UDP port number extracted this time is used.
If there is a previously received RTP frame having a DP port number, a difference between the sequence number of the UDP frame and the stored frame sequence number of the immediately preceding RTP frame is detected, and the difference detection result is set in advance. If the value is equal to or less than the predetermined value, the difference between the stored time stamp information of the immediately preceding frame and the time stamp information extracted from the current received frame and the stored time stamp of the immediately preceding RTP frame and the internal timer are obtained. The current time value is detected from the current time value, and the time stamp information extracted from the current reception frame and the current time value as the current RTP frame reception time are stored in a predetermined position corresponding to the extracted UDP port number on the external memory. To the time stamp of the previous frame. The difference between the information and the time stamp information extracted from the currently received frame is compared with the difference between the stored immediately preceding RTP frame reception time and the current time value obtained from the internal timer, and the difference between the two is negative. If the value is a negative value, control is performed to increase the transmission priority of the frame. If the value is not a negative value, control is performed so that a delay time is appropriately added to the frame.

According to a seventh aspect of the present invention, in each of the first to third aspects of the present invention, if the detection result of the difference between the sequence number of the frame and the previous frame sequence number is larger than a predetermined fixed value, Only the process of writing and storing the time stamp information extracted from the received frame and the current time value as the current RTP frame reception time at a predetermined position on the external memory corresponding to the extracted UDP port number is performed.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS According to the present invention, a communication relay device (generally, a router) which connects each area in an IP network and serves as a base for packet transfer is provided at a transmitting terminal (or an upstream communication relay device [layer 3 or higher]. Device such as a router that performs packet routing based on this information]], appropriately changes the transfer priority of the frame based on the frame sequence number (serial number), port number, and time stamp information in the RTP frame received from the RTP frame. And control as follows. By performing such a configuration and processing in the communication relay device corresponding to the transmission path of the RTP frame, it is possible to suppress the jitter of each received frame in the receiving terminal.

Embodiments The present invention will be described below with reference to embodiments and the accompanying drawings. First, the configuration of the embodiment will be described. FIG. 1 is a block diagram showing a schematic configuration of a packet transfer processing unit 100 (main functional unit in a general router) constituting a router as a communication relay device according to one embodiment of the present invention. The router includes a well-known power supply unit, a control unit, and the like as appropriate in addition to the packet transfer processing unit 100, but will not be described here.

The packet transfer processing unit 10 of the router according to the present embodiment
1 includes a UDP / RTP header detection unit 1 and a packet transfer unit 2 for analyzing the header of a well-known received packet, a packet queue 3 and a packet transmission unit 4, as shown in FIG. In particular, the UDP / RTP header detection unit 1 performs a general packet header analysis and a UD
It is configured to be able to extract and analyze the P / RTP header. In addition, the packet transmission unit 4 has a function of changing the priority of the transfer processing according to the degree of the jitter detected based on the received packet, as described later.

The packet transfer processing unit 100 further includes a time stamp difference detection unit 5, an internal timer difference detection unit 6, a jitter detection unit (difference comparison unit) 7, an internal timer 8, a first external memory 9, It comprises an external memory 10.

FIG. 1 shows a packet transfer processing unit according to this embodiment.
Characteristic components in 100 are clearly indicated by broken lines. Note that the internal timer 8, the first external memory 9, and the second external memory 10 are generally provided in a router or the like without being newly provided, and can be diverted.

In the UDP / RTP header detecting section 1,
UDP port number and RT in received RTP frame
Detect (extract) sequence number / time stamp information in the P header. The time stamp difference detection unit 5
Among the pieces of information detected by the P / RTP header detecting unit 1, the time stamp value in the frame is latched, and the time stamp value in the previous frame having the same UDP port number (if any) read from the first external memory 9 is used. (Time stamp difference value) is detected.

The internal timer difference detector 6 reads the frame reception time (current time) from the internal timer 8 and detects the difference from the previous frame reception time (internal timer difference value).

The jitter detecting section 7 (difference comparing section) compares the time stamp difference value with the internal timer difference value, calculates the difference, and notifies the packet transmitting section 4 of the result.

The function of each of the above components will be described in more detail. First, the UDP / RTP header detection unit 1 specifies
When a first RTP frame carrying a series of real-time data is received, a UDP port number, a frame sequence number, and a time stamp value are detected from the received frame, and the time stamp difference detection unit 5 and the internal timer are used as a signal Sa. The difference is sent to the difference detector 6.

The time stamp difference detecting section 5 having received the signal Sa stores the frame sequence number and the time stamp value as data in the first external memory 9 using the UDP port number as an address. Further, the internal timer difference detector 6 reads the time at which the signal Sa was received from the internal timer 8, stores the UDP port number as an address, and stores the frame sequence number and the internal timer value as data in the second external memory 10.

Subsequently, upon receiving the next RTP frame (referred to as the next frame), the UDP / RTP header detecting unit 1 detects the UDP port number, frame sequence number, and time stamp value from the next frame in the same manner as described above. And sends them to the time stamp difference detection unit 5 and the internal timer difference detection unit 6 as a signal Sa.

The time stamp difference detector 5 receiving the signal Sa latches the frame sequence number and the time stamp value using the UDP port number as an address, and registers the time stamp value stored in the first external memory 9 with the time stamp value. , And sends the calculation result to the jitter detection unit 7 as a difference value signal Sb.

Further, the internal timer difference detecting section 6 outputs the signal S
The time (data) is read from the internal timer 8, this time (data) is latched using the UDP port number as an address, and the difference from the internal timer value previously stored in the second external memory 10 is calculated. The calculation result is sent to the jitter detection unit 7 by the difference value signal Sc.

The jitter detector 7 calculates the difference between the received difference signal Sb and the received difference signal Sc, and
The calculated value (time data) is transmitted to the packet transmitting unit 4 as a signal Sd.

The packet transmitting section 4 receives the received signal Sd
The transfer priority of the UDP packet (the packet that arrives latest) is changed according to the value of. Various methods are known for specific processing contents at this time, and an example will be described in detail later.

Next, a series of operations of the packet transfer processing unit 100 of the router of the embodiment will be described with reference to FIGS. When receiving an RTP frame, the UDP / RTP header detection unit 1 detects a UDP port number / frame sequence number / time stamp value from the received frame. The UDP / RTP header detection unit 1 sends the detected value to the time stamp difference detection unit 5 and the internal timer difference detection unit 6 using the signal Sa (S10).

Each of the above values generally has the following meaning. [UDP port number]: UDP port number of the transmitting terminal. This is a number corresponding to the application being used. [Frame sequence number]: A number indicating the order of the RTP frames carrying the application.
[Time stamp value]: Indicates the transmission interval of the RTP frame of the transmitting terminal.

Subsequently, the time stamp difference detector 5
The operation at the time of receiving the signal Sa will be described with reference to the flowchart of FIG. First, the time stamp difference detection unit 5 uses the UDP port number as an address and latches the frame sequence number / time stamp value as data (S21).
Thereafter, the previous frame sequence number / time stamp value is read from the first external memory 9 using the UDP port number as an address (S22).

Here, it is determined whether or not the UDP port number is to be received for the first time (S23). If the UDP port number is to be received for the first time (can be determined by comparison with the value of the read data), S23; YES), the read value is discarded, and the frame sequence number / time stamp value obtained from the current signal Sa is written in the same address area as when the read was performed on the first external memory 9 (S27), and the process ends. .

If the UDP port number is not the first one to be received (S23; NO), the difference between the read value from the first external memory 9 and the frame sequence number obtained from the current signal Sa and the time The differences between the stamp values are calculated (S24).

Here, it is determined whether or not the result of calculating the difference between the sequence numbers is equal to or smaller than a predetermined fixed value (S25). The difference calculation result is sent to the jitter detection unit 7 as a signal Sb (S26), and the frame sequence number / time stamp value obtained from the current signal Sa is
The same address area on the first external memory 9 (address = UD
(P port number) (S27), and the process ends.

On the other hand, the result of calculating the difference between the sequence numbers is
If it is larger than a predetermined value (S25; N
O) Even if the UDP port number is the same, there is a possibility that the RTP frame carries another application, so the frame sequence number /
The process ends only by writing the time stamp value to the same address area on the first external memory 9 (S27). That is, the same processing as that in the case where the UDP port number described above is received for the first time is performed.

Next, the operation of the internal timer difference detector 6 when receiving the signal Sa will be described with reference to the flowchart of FIG.
The internal timer difference detector 6 latches the UDP port number as an address and the frame sequence number as data (S31). Then, an internal timer value (current time) is read from the internal timer 8 (S32). Then, using the UDP port number as an address, the second external memory 1
The stored frame sequence number / internal timer value is read from 0 (S33).

Here, it is determined whether or not the UDP port number is to be received for the first time (S34). If the UDP port number is to be received for the first time (determined from the value of the read data) (S34; YES) ), Discard the reading,
The frame sequence number obtained from the current signal Sa, and
Internal timer value (current time) read from internal timer 8
Is written (overwritten) in the same address area on the second external memory 10 (S38), and the process ends.

On the other hand, if the UDP port number is not the first time received (S34; NO), the read value, the frame sequence number obtained from the current signal Sa, and the internal timer value read from the internal timer 8 are read. The difference from (current time) is calculated (S35).

Here, it is determined whether or not the result of calculating the difference between the sequence numbers is equal to or smaller than a predetermined value (S36). If the result is equal to or smaller than the predetermined value (YES), the difference between the internal timer values is determined. The calculation result is sent as a signal Sc to the jitter detector 7 (S37), and the frame sequence number obtained from the current signal Sa and the internal timer value (current time) read from the internal timer 8 are sent to the second external Write processing is performed on the same address area on the memory 10 (S38),
The process ends.

The result of calculating the difference between the sequence numbers is
If it is larger than the predetermined value (S36; NO), the frame sequence number obtained from the current signal Sa and the internal timer value (current time) read from the internal timer 8 are used for the same reason as described above. Second external memory 10
The process is completed only by writing to the upper address area (S38).

In the jitter detecting section 7 to which the above-mentioned signals Sb and Sc are inputted, the RTP frame transmission interval (hereinafter referred to as “transmission interval”) of the transmitting terminal and the packet transfer based on the received signals Sb and Sc, respectively. The reception interval of the RTP frame in the processing unit (hereinafter referred to as the reception interval) can be known.

Here, the difference time (difference information) between the transmission interval and the reception interval indicates jitter. That is, the jitter is smaller as the difference time is closer to "0". This difference information ("
The transmission interval "-" the reception interval ") is transmitted to the packet transmission unit 4 by the signal Sd.

The packet transmitting section 4 receives the received signal Sd
(Signal Sd = "transmission interval"-"reception interval")
If the signal Sd ≧ “0”, appropriate delay insertion control is performed, and if the signal Sd <“0”, control such as increasing the transmission priority of the frame (transmitting with priority over other frames) is performed. By transmitting the frame, it is possible to absorb the jitter of a series of RTP packets and transfer the group downstream.

[0054]

As described above, according to the present invention,
In a communication relay device such as a router, the difference between the transmission interval of the RTP frame carrying real-time data from the terminal device on the transmitting side and the reception interval of the own device is monitored in real time, and the difference is made closer to "0". With the configuration as described above, and by performing the frame transmission processing by performing the above-described transfer control, an effect of transferring a packet with reduced jitter to a device connected downstream can be obtained,
Therefore, an effect is obtained that the predetermined receiving terminal device can suppress the jitter at the time of receiving each frame.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a schematic configuration of a packet transfer processing unit included in a communication relay device (router) according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an operation of a time stamp difference detection unit in the embodiment.

FIG. 3 is a flowchart illustrating an operation of an internal timer difference detection unit in the embodiment.

FIG. 4 is a schematic block diagram illustrating a packet communication system according to the present invention.

FIG. 5 is an explanatory diagram showing an example of a configuration of an RTP packet according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... UDP / RTP header detection part 2 ... Packet transfer part 3 ... Packet queue 4 ... Packet transmission part 5 ... Time stamp difference detection part 6 ... Internal timer difference detection part 7 ... Jitter detection part (difference comparison part) 8 ... Internal Timer 9: First external memory 10: Second external memory 100: Packet transfer processing unit

Claims (7)

[Claims] At least a communication protocol; RTP (Ra
pid Transport Protocol) and UDP (User Datagra
In the communication relay device in the communication network performing the packet communication using the RTP frame, the frame sequence number of the RTP frame, the UDP port number, and the time stamp information are extracted from the information in the header of the RTP frame received from the upstream communication device. A UDP / RTP header detector, and if there is a previously received RTP frame having the same UDP port number as the UDP port number extracted this time, the sequence number of the UDP frame and the stored previous RTP frame If the difference between the frame sequence number is detected and the difference detection result is equal to or smaller than a predetermined value, the stored time stamp information of the immediately preceding frame and the time stamp information extracted from the current received frame are compared with the stored time stamp information. And output the difference A time stamp difference detector for writing and storing the time stamp information extracted from the communication frame at a predetermined position corresponding to the extracted UDP port number on the external memory; and a UDP port number identical to the UDP port number extracted this time. If there is an immediately preceding RTP frame received before, the difference between the sequence number of the UDP frame and the stored frame sequence number of the immediately preceding RTP frame is detected, and the difference detection result is set to a predetermined constant value. In the following case, the stored immediately preceding RTP
Detects and outputs the difference between the frame reception time and the current time value obtained from the internal timer, and writes the current time value as a current RTP frame reception time at a predetermined position on the external memory corresponding to the extracted UDP port number. An internal timer difference detector for storing, a jitter detector for comparing output values of the internal timer difference detector and the time stamp difference detector and outputting a difference between the values, and data relating to the frame based on an output of the jitter detector. A communication relay device comprising: a packet transmission unit that determines the priority of transfer processing in the communication relay device so as to suppress stream jitter. 2. The packet transmitting section controls to increase the transmission priority of the frame when the signal received from the jitter detecting section has a negative value. The communication relay device according to claim 1, wherein control is performed so as to add. 3. If the detection result of the difference between the sequence number of the frame and the previous frame sequence number is larger than a predetermined value, the time stamp difference detector extracts the current frame from the currently received frame. The time stamp information is stored in the extracted U
Only the process of writing and storing at a predetermined position corresponding to the DP port number is performed.
Only performing a process of writing and storing the current time value as a TP frame reception time at a predetermined position corresponding to the extracted UDP port number on the external memory, and not performing the process in the jitter detector. The communication relay device according to claim 1. 4. The communication relay device according to claim 1, further comprising a packet queue that stores packets for each path and that is output-controlled by said packet transmission unit. 5. A method for suppressing jitter of an RTP packet in a communication relay device in a communication network that performs packet communication using at least a communication protocol; RTP and UDP, wherein the method is based on information in a header of an RTP frame received from an upstream communication device. The frame sequence number and UD of the frame
The P port number and the time stamp information are extracted, and based on the frame sequence number, the UDP port number and the time stamp information, the priority of the transfer processing in the own communication relay device is controlled so as to suppress the jitter of the data stream related to the frame. And a jitter suppressing method in the communication relay device. 6. The immediately preceding RTP which has the same UDP port number as the UDP port number extracted this time and has been received before.
If there is a frame, the difference between the sequence number of the UDP frame and the stored frame sequence number of the immediately preceding RTP frame is detected. If the difference detection result is equal to or smaller than a predetermined value, the frame is stored. Detecting the difference between the time stamp information of the immediately preceding frame and the time stamp information extracted from the currently received frame and the difference between the stored immediately preceding RTP frame reception time and the current time value obtained from the internal timer, The time stamp information extracted from the current reception frame and the current time value as the current RTP frame reception time are stored in the external memory as the extracted U
It is written and stored in a predetermined position corresponding to the DP port number, and is obtained from the difference between the time stamp information of the immediately preceding frame and the time stamp information extracted from the currently received frame, the stored time of the immediately preceding RTP frame and the internal timer. If the difference between the two differences is a negative value, control is performed to increase the transmission priority of the frame, and if the difference is not a negative value, the frame is appropriately delayed to the frame. Control to add time,
6. The method for suppressing jitter in a communication relay device according to claim 5, wherein: 7. When the detection result of the difference between the sequence number of the frame and the previous frame sequence number is larger than a predetermined value, the time stamp information extracted from the current reception frame and the reception of the current RTP frame are received. 7. The communication relay device according to claim 5, wherein only the process of writing and storing the current time value as a time at a predetermined position corresponding to the extracted UDP port number on the external memory is performed. Jitter suppression method.