JP2004194232A - Packet communication equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress quality deterioration of voice transmission as much as possible by controlling whether to apply header compression and multiplexing to a voice IP packet in accordance with the state of a transmission path. <P>SOLUTION: In packet communication equipment for applying header compression and multiplexing to the voice IP packet on the basis of a TCRTP, a packet output control part determines whether to apply header compression and multiplexing to an IP packet including real time information on the basis of the number of connections inputted from a connection control part, the amount of stored data inputted from a packet transmitting part, and the line state of the transmission path. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a packet communication device.
[0002]
[Prior art]
2. Description of the Related Art With the spread of the Internet, a technique of transmitting real-time information such as voice information using an IP network has attracted attention. VoIP (Voice over IP) is well known as a technology for transmitting voice information. In VoIP, voice information converted into a digital signal is divided into appropriate lengths, and RTP (Real-time Transport Protocol), UDP (User Datagram Protocol), and IP (Internet Protocol) headers are added to form IP packets. Hereinafter, the IP packet thus created is referred to as a voice IP packet.
[0003]
In a normal telephone network, voice information is converted into digital information of 64 kbit / s and transmitted. In VoIP, in order to save a communication band to be used, the voice information is converted to 8 kbit / s by applying a high-efficiency voice coding scheme. In general, the data is transmitted after being compressed to a band of about s. Since the amount of information generated within a certain period of time is reduced by compressing voice, in order to transmit the compressed voice information with low delay, the packet length of the voice IP packet must be adjusted according to the degree of voice information compression. It is necessary to set the length to be short and to perform IP packetization with a small amount of information. However, if the packet length of the voice IP packet is set to be short, the ratio of the header information to the entire voice IP packet increases, which causes a problem that the transmission efficiency decreases. For example, when an 8 kbit / s high-efficiency audio encoded signal is packetized every 20 msec, the audio information is 20 msec × 8 kbit / s = 160 bits = 20 bytes, but the header information is a 12-byte RTP header, 8 bytes. The UDP header of 20 bytes and the IP header of 20 bytes make a total of 40 bytes, and the header information occupies 2/3 of the voice IP packet.
[0004]
As a means for solving this problem, a CRTP (Compressed RTP) method for reducing the amount of information in the header by transmitting only the difference information of the header of the IP / UDP / RTP packet is described in RFC2508 by the Internet Engineering Task Force (IETF). Is defined as In the CRTP, on the receiving side, the IP / UDP / RTP header is restored based on the difference information of the received header and the header information of the previously received IP packet. However, in order to apply CRTP, there is a problem that all routers that pass through at the time of transmission must support CRTP.
[0005]
Therefore, in IETF, a method of multiplexing a plurality of voice IP packets whose headers are compressed by CRTP, adding an uncompressed IP header to the multiplexed data, and transmitting the multiplexed data as one IP packet is a TCRTP (Tunneling Multiplexed CRTP). It has been proposed as. By applying TCRTP, even if the router on the transmission path does not support CRTP, transmission efficiency can be improved by CRTP.
[0006]
However, in TCRTP, header compression is always performed on an input voice IP packet. Therefore, if one IP packet is lost, the subsequent header compressed IP packet cannot restore the header information from the difference information. Discarded. For this reason, there is a problem that the quality of the transmitted voice is degraded due to the continuous discarding of IP packets even though the bandwidth of the transmission path is sufficiently ensured.
[0007]
In order to solve this problem, for example, in the conventional packet communication device disclosed in Patent Document 1, when a full header packet received from a transmission terminal or a header compression packet due to CRTP is lost, the receiving device is Until a full header packet is received, all received header compression packets are held. The receiving-side device restores the compressed header of the held header compressed packet based on the content of the header of the full header packet received after the packet loss.
[0008]
[Patent Document 1]
JP-A-2002-26963
[0009]
[Problems to be solved by the invention]
As described above, in TCRTP, header compression and multiplexing are always performed on an input voice IP packet. When header compression is performed, if one IP packet is lost, subsequent IP packets cannot be used, and are continuously discarded. For this reason, even if the bandwidth of the transmission path is sufficiently ensured, there is a problem that the quality of voice transmission is reduced due to continuous discarding of IP packets. In TCRTP, since voice IP packets are transmitted as UDP packets, control for retransmitting packets lost on the transmission path is not performed. Therefore, when the loss of the IP packet occurs, there is a problem that the voice quality on the receiving side of all the channels related to the multiplexed IP packet is deteriorated.
[0010]
In the conventional packet communication device disclosed in Patent Literature 1, when a loss of an IP packet occurs, a process on the receiving side is performed to prevent a decrease in voice quality, but the compression is performed until a full header packet is received. Since the header cannot be restored, there is a problem that the data transmission delay increases.
[0011]
The present invention controls whether or not header compression and multiplexing of an audio IP packet are performed or not in accordance with the amount of data output to the transmission path and the state of the transmission path, and lowers the quality of voice transmission due to continuous discarding of IP packets. It aims at suppressing.
[0012]
[Means for Solving the Problems]
A packet communication device according to the present invention includes: an IP packet identification unit that identifies whether an input IP packet includes real-time information; and a connection to which the IP packet determined to include the real-time information by the IP packet identification unit belongs. A connection identification unit to be determined, a header compression unit for compressing a header of an IP packet containing real-time information for each connection, and multiplexing for generating a multiplexed IP packet by multiplexing an IP packet whose header is compressed by the header compression unit. A packet assembling unit, a packet sending unit that stores the multiplexed IP packet and sends it out to the transmission path, and determines whether or not to perform header compression and multiplexing of the IP packet including the real-time information. In this case, the IP packet determined to contain the real-time information by the IP packet A first transmission method selection unit that supplies the data to the data compression unit, the first transmission method selection unit includes a number of currently established connections, a data amount of IP packets currently stored in the packet transmission unit, And determining whether or not to perform header compression and multiplexing based on at least one of the IP packet loss rates on the transmission path.
[0013]
A packet communication device according to the present invention includes: an IP packet identification unit that identifies whether an input IP packet includes real-time information; and a connection to which the IP packet determined to include the real-time information by the IP packet identification unit belongs. A connection identification unit to be determined, a header compression unit that compresses a header of an IP packet including real-time information for each connection, a packet replication unit that creates a duplicate packet of the IP packet whose header is compressed by the header compression unit, and a duplicate packet Multiplexed packet assembling unit for separately multiplexing the original IP packet and the original IP packet to generate a multiplexed IP packet, a packet transmitting unit for storing the multiplexed IP packet and transmitting the multiplexed IP packet to the transmission line, and a compression unit for compressing the header It is determined whether or not to copy the received IP packet, and if this determination is affirmative, And a second transmission scheme selection unit for supplying the compressed IP packet to the packet duplication unit. The second transmission scheme selection unit is configured to store the currently established number of connections and the currently stored connection in the packet transmission unit. It is to determine whether to duplicate an IP packet based on at least one of the data amount of the existing IP packet and the loss rate of the IP packet on the transmission path.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, various embodiments of the present invention will be described.
Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of a packet communication device (packet concentrator 100) according to Embodiment 1 of the present invention. The packet concentrator 100 is a device that collects IP packets transmitted from a plurality of packet communication terminals belonging to a certain packet switching network and outputs the collected IP packets to a packet switching network or another packet concentrator. The packet concentrator 100 includes an IP packet identification unit 101, a connection identification unit 102, a connection-specific control unit 103, a multiplexed packet assembling unit 106, a packet transmission unit 107, and a multiplexed packet output control unit 108 (first transmission method selection unit). ).
The connection-specific control unit 103 is prepared for each connection accommodated by the packet concentrator 100. Each connection control unit 103 includes a changeover switch 104 (first transmission method selection unit) and a header compression unit 105.
[0015]
Next, the operation will be described.
First, an operation when a packet other than a voice IP packet (hereinafter, referred to as a non-voice IP packet) is input to the packet concentrator 100 will be described. The IP packet received by the packet concentrator 100 is input to the IP packet identification unit 101. The IP packet identification unit 101 refers to the header information of the input IP packet and identifies whether or not the packet is a voice IP packet. Specifically, if a value indicating UDP is not stored in the “Protocol” area of the IP header shown in FIG. 2, it is regarded as a non-voice IP packet. If a value indicating UDP is stored in the “Protocol” area of the IP header, the IP packet identification unit 101 checks the “destination port” of the UDP header, and sets the port number to a value corresponding to the voice IP packet. If it is not stored, it is regarded as a non-voice IP packet.
[0016]
When determining that the input IP packet is a non-voice IP packet, IP packet identifying section 101 outputs the IP packet to packet transmitting section 107. The packet transmitting unit 107 temporarily stores the received non-voice IP packet in its own buffer (not shown), and then transmits the packet to the IP network. Further, the packet transmitting unit 107 periodically checks the total length of all IP packets stored in the buffer, and supplies the result of the check to the multiplexed packet output control unit 108 as the current accumulated data amount.
[0017]
Next, an operation when a voice IP packet is input to the packet concentrator 100 will be described.
[0018]
The IP packet input to the packet concentrator 100 is identified by the IP packet identification unit 101 as to whether it is a voice IP packet. If a value indicating UDP is stored in the “Protocol” area of the IP header and a value corresponding to the voice IP packet is stored in the port number of the UDP header, it is regarded as a voice IP packet. When determining that the input IP packet is a voice IP packet, IP packet identification section 101 outputs a voice IP packet to connection identification section 102.
[0019]
Next, the connection identification unit 102 identifies the connection to which the audio IP packet belongs with reference to the header information of the audio IP packet input from the IP packet identification unit 101. The connection identification unit 102 identifies a connection based on “source IP address” and “destination IP address” of the IP header in the IP packet, “source port” and “destination port” of the UDP header, and the like.
The connection identification unit 102 has a connection identification table (not shown) for associating the information necessary for the connection identification with the connection control unit 103 corresponding to each connection. The connection identification unit 102 refers to the connection identification table every time a voice IP packet is input, and if there is no connection that matches the connection identified from the header information of the input voice IP packet in the table, a new connection is created. It is determined that the connection is made. In this case, the connection identification unit 102 extracts information necessary for identifying a connection from the input voice IP packet, registers the information in the connection identification table, and assigns an unused connection-specific control unit 103 to the connection identification unit. Register information. Then, the input voice IP packet is output to the assigned connection-specific control unit 103.
On the other hand, when the connection to which the input voice IP packet belongs already exists in the connection identification table, the information of the corresponding connection-specific control unit 103 is obtained from the connection identification table, and the voice IP packet is Are output to the connection-specific control unit 103.
Further, the connection identification unit 102 periodically checks the connection identification table. If there is a connection in which no voice IP packet has been input for a certain period of time, the connection identification unit 102 determines that the connection has ended, and uses the information of the connection for connection identification. In addition to the deletion from the table, the corresponding connection-specific control unit 103 is released. In addition, the connection identification unit 102 periodically checks the number of connections stored in the connection identification table, and outputs the checked result to the multiplexed packet output control unit 108 as the current number of connections.
[0020]
Next, the operation of the connection-specific control unit 103 will be described. The connection-specific control unit 103 selects a route of the voice IP packet input from the connection identification unit 102 by using the changeover switch 104. When the changeover switch 104 is selecting a route to the packet transmitting unit 107, the voice IP packet is output to the packet transmitting unit 107.
[0021]
The packet transmitting unit 107 receives the voice IP packet input from the connection-specific control unit 103 and stores the voice IP packet in a buffer. Then, the packet transmitting unit 107 transmits the voice IP packet stored in the buffer to the IP network. The packet transmitting unit 107 periodically checks the total length of all the IP packets stored in the buffer, and outputs the result of the check to the multiplexed packet output control unit 108 as the current accumulated data amount.
[0022]
On the other hand, when the changeover switch 104 has selected the path to the header compression unit 105, the header compression unit 105 compresses the IP / UDP / RTP header of the input voice IP packet. The compression of the IP / UDP / RTP header is performed based on the CRTP rules. As described in connection with the related art, CRTP reduces the amount of information in the header by transmitting only the difference information of the header of the IP / UDP / RTP packet.
[0023]
FIG. 3 is a diagram illustrating a method of header compression and multiplexing processing of an IP packet by TCRTP. The voice IP packet 301 indicates an IP packet for transmitting voice information. The header compression unit 105 compresses the input IP / UDP / RTP header of the voice IP packet 301 according to CRTP, and generates a CRTP packet 302.
[0024]
However, in the CRTP, an IP packet received first is transmitted as a full header without compressing the IP / UDP / RTP header. For the second and subsequent received IP packets, the IP / UDP / RTP header is compressed into the compressed header shown in FIG. Details of the information stored in each area of the compressed header are defined in RFC2508 issued by IETF, and thus the description is omitted here.
[0025]
The CRTP packet 302 output by the header compression unit 105 is input to the multiplexed packet assembling unit 106. The multiplexed packet assembling unit 106 multiplexes the CRTP packets output by the header compression unit 105 of each connection-specific control unit 103, and generates a multiplexed packet 303. The multiplexing of the CRTP packet is performed based on the TCRTP specification. In TCRTP, as a multiplexing method, Point-To-Point Protocol Multiplexing (PPPMUX) is applied. In PPPMUX, a multiplex header shown in FIG. 5 is added to each CRTP packet. The details of the information stored in each area of the multiplexed header are specified in RFC3153 issued by IETF, and thus the description is omitted here.
[0026]
The multiplexed packet assembling unit 106 multiplexes the CRTP packet 302 to which the multiplexed header is added, and adds “Mux PPP Protocol Field” (1 byte) as header information to the multiplexed CRTP packet. Thus, the multiplexed packet 303 is created.
[0027]
Next, the multiplexed packet assembling unit 106 creates an IP packet 304 by adding an IP header to the multiplexed packet 303.
[0028]
The IP packet 304 created by the multiplexed packet assembling unit 106 is output to the packet sending unit 107 and sent out to the IP network by the packet sending unit 107.
[0029]
Next, the operation of the multiplexed packet output control unit 108 will be described. The multiplexed packet output control unit 108 compares the current number of connections notified from the connection identification unit 102 with a preset threshold value (threshold value A) of the number of connections. If the number of connections is small, the number of IP packets that can be multiplexed will be small, and the effect of data reduction by multiplexing will be low. For example, when there is only one connection of the input voice IP packet, the effect of the multiplexing process is very low. Conversely, if the number of connections is large, the number of IP packets is large, and the multiplexing efficiency is high. When determining that the current number of connections notified from the connection identification unit 102 is larger than the threshold value A, the multiplexed packet output control unit 108 selects a path to the header compression unit 105 for the changeover switch 104. A control signal to be output is output.
[0030]
On the other hand, when it is determined that the current number of connections received from the connection identification unit 102 is smaller than the threshold A, the multiplexed packet output control unit 108 The total length of the IP packets in the buffer is compared with the threshold value B. If the amount of data stored in the packet sending unit 107 is large, the load on the IP network that outputs IP packets increases, and if the amount of stored data is small, the load on the IP network decreases. As a result of the comparison, if the multiplexed packet output control unit 108 determines that the current stored data amount notified from the packet transmission unit 107 is larger than the threshold value B, the multiplexed packet output control unit 108 Output a control signal to select a route to
[0031]
On the other hand, if it is determined that the current number of connections received from the connection identification unit 102 is smaller than the threshold value A and the current amount of stored data received from the packet transmission unit 107 is smaller than the threshold value B, The multiplexed output control unit 108 compares the packet loss rate notified from other packet concentrators and the like with a preset threshold value of the packet loss rate (threshold value C). Other packet concentrators and the like detect packet loss from the received IP packet header information and the like, and notify the packet concentrator 100 of the packet loss rate. The packet loss rate indicates the quality of the line state of the IP network. If the packet multiplexing output control unit 108 determines that the packet loss rate is lower than the threshold value C as a result of the comparison, the packet multiplexing output control unit 108 outputs a control signal for causing the changeover switch 104 to select a path to the header compression unit 105. .
[0032]
On the other hand, if it is determined that the packet loss rate received from another packet concentrator or the like is higher than the threshold value C, the multiplexed packet output control unit 108 A control signal for selecting a path is output.
[0033]
As described above, according to the first embodiment, the multiplexed packet output control unit 108 controls the number of currently established connections, the amount of stored data output from the packet transmitting unit 107 to the IP network, and the Since the path of the changeover switch 104 is controlled based on the line state, the header compression and multiplexing of the voice IP packet are performed when there is room in the bandwidth of the transmission path for the amount of data to be transmitted. In this case, it is possible to suppress a decrease in quality of voice transmission due to continuous discarding of IP packets.
[0034]
The multiplexed packet output control unit 108 switches the path of the changeover switch 104 based on the number of connections input from the connection identification unit 102, so that when packet multiplexing efficiency is low, header compression and It is possible to transmit voice IP packets without performing multiplexing, and it is possible to effectively use the bandwidth of the transmission path and suppress deterioration of voice quality due to packet loss.
[0035]
Further, the multiplexed packet output control unit 108 switches the path of the switch 104 based on the output data amount notified from the packet transmission unit 107. For example, when the frequency at which the packet transmission unit 107 becomes empty is high, the output load on the transmission path is considered to be low. In such a case, transmission is performed without performing header compression and multiplexing. Therefore, it is possible to suppress the deterioration of the voice quality due to the packet loss according to the load on the transmission path.
[0036]
Further, the multiplexed packet output control unit 108 switches the path of the switch 104 based on the packet loss rate notified from another packet concentrator or the like. For example, when the packet loss rate is high, it is considered that voice quality is likely to deteriorate due to packet loss. In such a case, transmission is performed without performing header compression and multiplexing. Therefore, it is possible to suppress the deterioration of the voice quality according to the line state of the transmission path.
[0037]
The multiplexed packet output control unit 108 determines the current number of connections notified from the connection identification unit 102, the current accumulated data amount notified from the packet transmission unit 107, the packet loss notified from other packet concentrators, and the like. The control signal for path selection to be output to the changeover switch 104 may be determined based on any one or two values of the rates.
[0038]
Also, the thresholds A, B, and C used for condition determination of the current number of connections, the current amount of stored data, and the packet loss rate may be dynamically changed. For example, if the respective thresholds are varied according to the current number of connections, an appropriate amount of IP packets can be header-compressed, multiplexed and transmitted according to the multiplexing efficiency of the packets. Further, if each threshold value is changed according to the current amount of stored data, an appropriate threshold value can be set according to the load on the transmission path. Further, by changing each threshold value according to the packet loss rate on the transmission path, an appropriate threshold value can be set according to the state of the line. The threshold may be determined by combining these conditions.
[0039]
The multiplexed packet output control unit 108 controls the compression of IP packets to be transmitted according to the line state of the transmission path based on the packet loss rate input from another packet concentrator or the like. It can also be controlled based on the congestion state of a router relayed on the road. In this case, if the packet loss rate is high, it is considered that congestion has occurred in the router relayed on the transmission path, so that control can be performed to suppress the number of IP packets by performing header compression and multiplexing.
[0040]
In the first embodiment, when the current number of connections, the current amount of stored data, and the packet loss rate satisfy the conditions, the multiplexed packet output control unit 108 switches the paths to the changeover switches 104 of all the connection-specific control units 103. Is output. However, when the path of the changeover switch 104 is switched, the processing delay fluctuates due to the change of the IP packet transmission method, which leads to deterioration of voice quality. Therefore, only the connection newly generated after the path switching condition is satisfied may be configured to switch the path of the switch 104 of the corresponding connection-specific control unit 103. In this case, the multiplexed packet control unit 108 acquires from the connection identification unit 102 the information of the connection-specific control unit 103 corresponding to the newly generated connection after judging that all the conditions for the path switching are satisfied. Then, it outputs a route selection control signal only to the changeover switch 104 of the connection-specific control unit 103. By performing such control, it is possible to prevent fluctuations in processing delay caused by switching of the transmission method, and to suppress deterioration in voice quality.
[0041]
In the first embodiment, when the current number of connections, the current amount of stored data, and the packet loss rate satisfy the conditions, the multiplexed packet output control unit 108 immediately switches the path of the changeover switch 104. Alternatively, a silent portion of the audio signal included in the IP packet of each connection may be detected, and when the silent portion is detected, the path of the corresponding switch 104 of the connection-specific control unit 103 may be switched. Specifically, when a voice IP packet is input to each connection control unit 103, first, a voice data determination unit (not shown) detects a silent portion. The multiplexed packet output control unit 108 receives the detection result from the audio data determination unit of each connection-specific control unit 103, and outputs a control signal to the changeover switch 104 of the corresponding connection-specific control unit 103 when silence is detected. I do. As described above, by changing the transmission method in the silent part of the audio signal, it is possible to prevent the fluctuation of the processing delay caused by the change in the transmission method from occurring in the sound part of the audio signal. Can be suppressed.
[0042]
Further, in the first embodiment, the multiplexed packet assembling unit 106 converts the multiplexed packet (multiplexed packet 303) based on the TCRTP specification into an IP packet and outputs it to the packet transmitting unit 107. If the transmission path between the devices does not pass through a router, the multiplexed packet may be transmitted without being converted into an IP packet. As a result, the overhead of the IP header added to the multiplexed packet can be reduced, and the transmission efficiency can be improved even on a transmission line that does not pass through a router.
[0043]
Also, in the first embodiment, only the audio IP packet is subjected to header compression and multiplexing in the IP packet identification unit 101. However, in addition to the audio IP packet, the IP packet including real-time information such as video is subjected to header compression and multiplexing. It may be a target of multiplexing.
[0044]
In the first embodiment, the voice IP packet and the non-voice IP packet are stored in the same buffer in the packet transmitting unit 107. However, separate packets for the voice IP packet and the non-voice IP packet are stored in the packet transmitting unit 107. A buffer may be prepared, and IP packets stored in the voice IP packet buffer may be preferentially output.
[0045]
Further, in the first embodiment, the packet concentrator 100 receives an IP packet from a packet communication terminal, but may receive an IP packet from a device other than the packet communication terminal. For example, the present invention can be applied to a case where an IP packet is received from a relay device such as a router or an exchange.
[0046]
Embodiment 2 FIG.
FIG. 6 is a block diagram showing a configuration of the packet communication device according to the second embodiment of the present invention. A case where the present invention is applied to a packet concentrator as in the first embodiment will be described. In the figure, the same symbols as those in FIG. 1 indicate the same components, and operate in the same manner as in the first embodiment. In the packet concentrator 200 according to the second embodiment, as shown in FIG. 6, a connection-specific control unit 202 instead of the connection-specific control unit 103 and a multiplexed packet output control unit 205 instead of the multiplexed packet output control unit 108 (Second transmission scheme selection unit), includes a multiplexed packet assembling unit 204 instead of the multiplexed packet assembling unit 106, and a packet duplicating unit 203. The connection-specific control unit 202 is prepared for each connection accommodated by the packet concentrator 200. Each connection-specific control unit 202 has a changeover switch 201 (second transmission method selection unit). The multiplexed packet assembling unit 204 operates in the same manner as the multiplexed packet assembling unit 106 of the first embodiment, but fetches the CRTP packets output from the connection-specific control unit 202 and the packet duplication unit 203 into separate buffers. The point of multiplexing is different.
[0047]
Next, the operation will be described.
The operation when a non-voice IP packet is input to the packet concentrator 200 is the same as in the first embodiment, and a description thereof will be omitted. Also, the case where a voice IP packet is input to the packet concentrator 200 and the changeover switch 104 selects a route to the packet transmitting unit 107 according to a control signal from the multiplexed packet output control unit 205 is the same as in the first embodiment. Since the operation is similar, the description is omitted. The conditions for control by the multiplexed packet output control unit 205 will be described later.
[0048]
Further, a voice IP packet is input to the packet concentrator, and the changeover switch 104 selects a route to the header compression unit 105 according to a control signal from the multiplexed packet output control unit 205, and the changeover switch 201 sets the multiplexed packet assembly. The case where the path to the unit 204 is selected is the same as the operation in the first embodiment when the changeover switch 104 selects the path to the header compression unit 105.
[0049]
The voice IP packet is input to the packet concentrator 200, and the changeover switch 104 selects a route to the header compression unit 105 according to a control signal from the multiplexed packet output control unit 205, and the changeover switch 201 sets the packet duplication unit 203 The operation in the case of selecting a route to is described. In this case, the IP packet input to the packet concentrator 200 is identified as a voice IP packet, and after being input to the connection-specific control unit 202, the header is compressed by the header compression unit 105 and the CRTP packet is The operation up to the output of "." Is the same as that of the first embodiment, and a description thereof will be omitted.
[0050]
The CRTP packet output from the header compression unit 105 is input to the packet duplication unit 203 according to the path selected by the changeover switch 201. The packet copying unit 203 copies the input CRTP packet. As a result, two CRTP packets having the same information are obtained. Then, these two CRTP packets are output to multiplexed packet assembling section 204.
[0051]
The multiplexing packet assembling unit 204 multiplexes the CRTP packet input from the packet duplicating unit 203. The multiplexed packet assembling unit 204 has two multiplexing buffers, and when two identical CRTP packets are input, stores the respective CRTP packets in separate multiplexing buffers. Then, the CRTP packets stored in the respective multiplexing buffers are multiplexed, and an IP header is added to make them into IP packets. Note that the multiplexing of the CRTP packet is the same as the TCRTP method described in the first embodiment, and a description thereof will be omitted.
[0052]
Next, the multiplexed packet assembling section 204 outputs the multiplexed IP packet to the packet transmitting section 107. The packet transmitting unit 107 stores the IP packet output from the multiplexed packet assembling unit 204 in a buffer, and then transmits the IP packet to the IP network. Further, the packet transmitting unit 107 periodically checks the total length of all IP packets stored in the buffer, and outputs the result of the check to the multiplexed packet output control unit 205 as the current stored data amount.
[0053]
Next, the operation of the multiplexed packet output control unit 205 will be described. First, the multiplexed packet output control unit 205 receives the notification of the current number of connections from the connection identification unit 102, and compares it with a preset threshold value of the number of connections (threshold A). Next, the multiplexed packet output control unit 205 receives the current stored data amount from the packet transmission unit 107 and compares it with a preset data amount threshold (threshold B). Next, the packet multiplexing output control unit 205 receives the packet loss rate from another packet concentrator or the like on the transmission path and compares it with a preset threshold value (threshold value C) of the packet loss rate.
[0054]
As a result of the comparison, it is determined that the current number of connections received from the connection identification unit 102 is larger than the threshold value A, or the current stored data amount received from the packet transmission unit 107 is larger than the threshold value B. If the multiplexed packet output control unit 205 determines that the path is also large, the multiplexed packet output control unit 205 outputs a control signal for causing the changeover switch 104 to select a path to the header compression unit 105. Further, a control signal for selecting a route to the multiplexed packet assembling section 204 is output to the switch 201.
[0055]
It is determined that the current number of connections notified from the connection identification unit 102 is smaller than the threshold value A, and that the current accumulated data amount notified from the packet transmission unit 107 is smaller than the threshold value B, If it is determined that the packet loss rate notified from another packet concentrator is higher than the threshold value C, the multiplexed packet output control unit 205 sends the header compression unit 105 Output a control signal to select a route to Further, a control signal for selecting a route to the packet duplication unit 203 is output to the changeover switch 201.
[0056]
Further, it is determined that the current number of connections notified from connection identification section 102 is smaller than threshold value A, and that the current amount of stored data notified from packet transmission section 107 is smaller than threshold value B. If it is determined that the packet loss rate notified from another packet concentrator or the like is lower than the threshold value C, the multiplexed packet output control unit 205 sends a packet transmission unit A control signal for selecting a path to 107 is output.
[0057]
As described above, according to the second embodiment, the multiplexed packet output control unit 205 determines whether the number of currently established connections, the amount of stored data output from the packet transmitting unit 107 to the IP network, and the transmission path Since the paths of the changeover switch 104 and the changeover switch 201 are controlled based on the line state, the output load of the IP packet is low, the multiplexing efficiency of the packet is low, and the line state of the transmission line is good. Thus, it is possible to transmit the audio IP packet to the transmission path without performing header compression and multiplexing, thereby suppressing the deterioration of the audio quality due to the discard of the CRTP packet.
[0058]
Further, according to the second embodiment, when the output load of the IP packet is low, the multiplexing efficiency of the packet is low, and the line state of the transmission path is poor, the packet duplication section 203 converts the header-compressed IP packet into a packet. Since the duplicated and multiplexed packet assembling unit 204 multiplexes the duplicated IP packet separately from the original IP packet and sends the multiplexed packet to the transmission path, loss of the CRTP packet on the transmission path can be suppressed.
[0059]
In the second embodiment, the conditions for switching the paths of the changeover switch 104 and the changeover switch 201 include the current number of connections notified from the connection identification unit 102, the current storage data amount notified from the packet transmission unit 107, and The packet loss rate notified from another packet concentrator or the like is used, but the path of the changeover switch 104 and the changeover switch 201 is switched using any one or any two of these conditions. You may do so.
[0060]
Also, the thresholds A, B, and C used for condition determination of the current number of connections, the current amount of stored data, and the packet loss rate may be dynamically changed. For example, if the respective thresholds are varied according to the current amount of stored data, an appropriate amount of IP packets can be header-compressed, multiplexed and transmitted according to the load on the transmission path. . Further, by changing each threshold value according to the packet loss rate on the transmission path, an appropriate threshold value can be set according to the state of the line. The threshold may be determined by combining these conditions.
[0061]
Further, in the second embodiment, when the current number of connections, the current amount of stored data, and the packet loss rate satisfy the conditions, the multiplexed packet output control unit 205 controls the changeover switches 104 of all the connection control units 202 or A control signal for switching the path is output to the changeover switch 201. However, when the paths of the changeover switch 104 and the changeover switch 201 are switched, the processing delay fluctuates due to the change in the transmission method of the IP packet, and the voice quality is degraded. Therefore, only the connection newly generated after the condition of the path switching is satisfied may be configured to switch the path of the changeover switch 104 or the changeover switch 201 of the corresponding connection-specific control unit 202. In this case, the multiplexed packet control unit 205 acquires from the connection identification unit 102 the information of the connection-specific control unit 202 corresponding to the newly generated connection after judging that the condition of the path switching is satisfied. Then, it outputs a route selection control signal only to the changeover switch 104 or the changeover switch 201 of the connection-based control unit 202. By performing such control, it is possible to prevent fluctuations in processing delay caused by switching of the transmission method, and to suppress deterioration in voice quality.
[0062]
In the second embodiment, when the current number of connections, the current amount of stored data, and the packet loss rate satisfy the conditions, the packet multiplexing output control unit 205 immediately switches the path of the switch 104 or the switch 201. Although switching is performed, a silent portion of the audio signal included in the IP packet of each connection is detected, and when the silent portion is detected, the path of the switch 104 or the switch 201 of the corresponding connection-specific control unit 202 is switched. It may be. Specifically, when a voice IP packet is input to each connection control unit 202, first, a voice data determination unit (not shown) detects a silent portion. The multiplexed packet output control unit 205 outputs a control signal to the changeover switch 104 or the changeover switch 201 of each connection-specific control unit 202. As described above, by changing the transmission method in the silent portion of the audio signal, it is possible to prevent the fluctuation of the processing delay caused by the change in the transmission method from occurring in the voiced portion of the audio signal, thereby deteriorating the audio quality. Can be suppressed.
[0063]
Further, in the second embodiment, the multiplexed packet assembling section 204 converts the multiplexed packet based on the TCRTP into an IP packet and outputs it to the packet transmitting section 107. When not passing through a router, the multiplexed packet may be transmitted without being converted into an IP packet. As a result, the overhead of the IP header added to the multiplexed packet can be reduced, and the transmission efficiency can be improved even on a transmission line that does not pass through a router.
[0064]
Further, in the second embodiment, the processing path of the IP packet is switched using the changeover switch 104 and the changeover switch 201. However, the changeover switch 104 is deleted, and the IP packet input to the connection-specific control unit 202 always has the header. The data may be input to the compression unit 105, and only the copy control of the CRTP packet may be controlled using the changeover switch 201.
[0065]
Further, in the second embodiment, the CRTP packets corresponding to all the connections are set as targets of duplication by the packet duplication unit 203. However, priority is set for each connection, and only the CRTP packets corresponding to the high-priority connections are set. Duplication may be performed.
[0066]
Further, in the second embodiment, all the CRTP packets are to be copied by the packet copying unit 203. However, the copying may be performed only when the header of the CRTP packet is sufficiently compressed. In header compression by CRTP, the header length after compression is at most the same as the header length before compression. When such a CRTP packet is copied, the output load on the transmission path increases significantly. Therefore, by making the copy target only when the header is sufficiently compressed by the header compression, it is possible to prevent the output load on the transmission path from being significantly increased.
[0067]
Also, in the second embodiment, only the audio IP packet is subjected to header compression and multiplexing in the IP packet identification unit 101. However, in addition to the audio IP packet, an IP packet including real-time information such as video may be used as a header. It may be a target of compression and multiplexing.
[0068]
Further, in the second embodiment, the voice IP packet and the non-voice IP packet are stored in the same buffer in the packet transmitting unit 107. However, separate packets for the voice IP packet and the non-voice IP packet are stored in the packet transmitting unit 107. A buffer may be prepared, and IP packets stored in the voice IP packet buffer may be preferentially output.
[0069]
In the second embodiment, the packet concentrator 100 receives an IP packet from a packet communication terminal, but may receive an IP packet from a device other than the packet communication terminal. For example, the present invention can be applied to a case where an IP packet is received from a relay device such as a router or an exchange.
[0070]
【The invention's effect】
As described above, according to the present invention, the multiplexed packet output control unit determines the number of connections input from the connection control unit, the amount of stored data input from the packet transmission unit, and the line state of the transmission path. Since it is determined whether or not to perform header compression and multiplexing of the IP packet including the real-time information, the header compression and multiplexing of the voice IP packet are performed according to the amount of data output to the transmission path and the state of the transmission path. Is performed, and the quality of voice transmission due to continuous discarding of IP packets is suppressed as much as possible.
[0071]
As described above, according to the present invention, the multiplexed packet output control unit determines the number of connections input from the connection control unit, the amount of stored data input from the packet transmission unit, and the line state of the transmission path. Since it is determined whether or not to copy an IP packet whose header has been compressed, it is determined whether to copy an IP packet whose header is compressed according to the amount of data to be output to the transmission path and the state of the transmission path. It is possible to control whether or not the transmission is performed, and to suppress as much as possible the deterioration of the voice transmission quality due to the loss of the IP packet.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a packet communication device according to a first embodiment of the present invention.
FIG. 2 is a diagram showing a configuration of an IP header, a UDP header, and an RTP header.
FIG. 3 is a diagram showing a method of header compression and multiplexing processing of an IP packet by TCRTP.
FIG. 4 is a diagram showing a configuration of a compressed header by CRTP.
FIG. 5 is a diagram showing a configuration of a multiplex header according to TCRTP.
FIG. 6 is a block diagram showing a configuration of a packet communication device according to a second embodiment of the present invention.
[Explanation of symbols]
100, 200 packet concentrator, 101 IP packet identification unit, 102 connection identification unit, 103, 202 connection-specific control unit, 104 changeover switch (first transmission method selection unit), 105 header compression unit, 106, 204 multiplexed packet Assembling unit, 107 packet sending unit, 108 multiplexed packet output control unit (first transmission method selection unit), 201 changeover switch (second transmission method selection unit), 203 packet duplication unit, 205 multiplexed packet output control unit (Second transmission method selection unit), 301 voice IP packet, 302 CRTP packet, 303 multiplexed packet, 304 IP packet.

Claims (10)

An IP packet identification unit for identifying whether or not the input IP packet includes real-time information;
A connection identification unit that determines a connection to which the IP packet determined to include the real-time information belongs by the IP packet identification unit;
A header compression unit for compressing a header of an IP packet including real-time information for each connection;
A multiplexed packet assembler for multiplexing the IP packets whose headers have been compressed by the header compressor to generate multiplexed IP packets;
A packet transmitting unit that stores the multiplexed IP packet and transmits the multiplexed IP packet to a transmission path;
It is determined whether to perform header compression and multiplexing of the IP packet including the real-time information. If the determination is affirmative, the IP packet identified by the IP packet identification unit as having the real-time information is subjected to the header compression. A first transmission scheme selection unit that supplies the transmission unit
The first transmission scheme selection unit is configured to determine at least one of a number of currently established connections, a data amount of IP packets currently stored in the packet transmission unit, and a loss rate of IP packets on the transmission path. A packet communication device that determines whether to perform header compression and multiplexing. The first transmission method selection unit determines at least one of the number of currently established connections, the data amount of the IP packet currently stored in the packet transmission unit, and the loss rate of the IP packet on the transmission path, based on the values. 2. The packet communication device according to claim 1, wherein a determination is made as to whether or not to perform header compression and multiplexing by comparing with a threshold value that is dynamically changed based on the threshold value. 3. The method according to claim 1, wherein the first transmission scheme selection unit supplies only the IP packet belonging to the newly generated connection to the header compression unit after determining that header compression and multiplexing are to be performed. The packet communication device according to claim 1. 4. The first transmission scheme selection unit supplies an IP packet to a header compression unit when a silent portion of audio information included in an IP packet of each connection is detected. The packet communication device according to claim 1. 5. The packet communication device according to claim 1, wherein the multiplexed packet assembling unit outputs the multiplexed IP packet to the packet transmitting unit without adding an IP header. An IP packet identification unit for identifying whether or not the input IP packet includes real-time information;
A connection identification unit that determines a connection to which the IP packet determined to include the real-time information belongs by the IP packet identification unit;
A header compression unit for compressing a header of an IP packet including real-time information for each connection;
A packet duplication unit that creates a duplicate packet of the IP packet whose header has been compressed by the header compression unit;
A multiplexed packet assembler for separately multiplexing the duplicated packet and the original IP packet to generate a multiplexed IP packet;
A packet transmitting unit that stores the multiplexed IP packet and transmits the multiplexed IP packet to a transmission path;
The compression unit determines whether to copy the header-compressed IP packet. If the determination is affirmative, a second transmission for supplying the header-compressed IP packet to the packet copy unit is performed. With a method selection unit,
The second transmission scheme selection unit is configured to determine at least one of a number of currently established connections, a data amount of IP packets currently stored in the packet transmission unit, and a loss rate of IP packets on the transmission path. A packet communication device that determines whether to duplicate an IP packet. The second transmission method selection unit determines at least one of the number of currently established connections, the data amount of the IP packet currently stored in the packet transmission unit, and the loss rate of the IP packet on the transmission path, based on the values. 7. The packet communication device according to claim 6, wherein whether or not to copy the IP packet whose header is compressed is determined by comparing with a threshold value that is dynamically changed based on the threshold value. 8. The packet communication according to claim 6, wherein the second transmission method selection unit supplies only the IP packet belonging to the newly generated connection to the header compression unit after determining that the duplication is to be performed. apparatus. 9. The method according to claim 6, wherein the second transmission scheme selection unit supplies the IP packet to the header compression unit when a silent part of the audio information included in the IP packet of each connection is detected. The packet communication device according to claim 1. 10. The packet communication device according to claim 6, wherein the multiplexed packet assembler outputs the multiplexed IP packet to the packet transmitter without adding an IP header to the multiplexed IP packet.

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