JP5127729B2 - Packet relay method and gateway device - Google Patents

Description

  The present invention relates to a packet relay method and a gateway device in a network system that includes a gateway device that exists between an existing terminal and a call control network and that performs call control processing during packet communication between existing terminals. is there.

  Originally, a network that introduces the concept of a session and guarantees QoS (Quality of Service) such as a communication band on an IP (Internet Protocol) network based on best effort has been constructed. In order to connect to such a network or to benefit from session control, each terminal needs to support a protocol for session control, but all existing terminals support this session control protocol. Is difficult. For this reason, a method has been proposed in which a gateway device that exists between a terminal and a network and relays packets between the terminal and the network performs a session control process with the network (for example, Patent Document 1). reference).

International Publication No. 2006/051594 Pamphlet

  In the gateway device, when performing session control processing, one session in the network is assigned to one communication flow between existing terminals. For this reason, in the conventional session control proxy method, all packets of a single communication flow are handled in the network as a single communication class declared to the network by the gateway device during session control. However, there is a problem that a plurality of communication classes cannot be used.

  The present invention has been made to solve the above-described problems. When proxying session control processing, a plurality of communication classes can be used by assigning a plurality of sessions to one communication flow. It is an object of the present invention to obtain a packet relay method and a gateway device that can be used.

  The packet relay method according to the present invention is a packet relay method in a network system including a gateway device that exists between an existing terminal and a call control network and that performs call control processing during packet communication between the existing terminals. Establish multiple communication paths with different priority classes for a single communication flow between existing terminals, identify the priority of communication packets between existing terminals, and relay according to the priority of the identified packets It is characterized by sorting communication paths.

  A gateway device according to the present invention is a gateway device that exists between an existing terminal and a call control network and that performs call control processing during communication between the existing terminals, and is a packet relay / distribution process. A packet relay / distribution processing unit, a priority identification unit for identifying the priority of a packet relayed by the packet relay / distribution processing unit, and a control unit that performs a call control process between the call control network The control unit establishes a plurality of communication paths with different priority classes for a single communication flow between existing terminals, and identifies the priority of communication packets between existing terminals by the priority identifying unit. The communication path to be relayed is distributed according to the priority of the identified packet.

  According to the present invention, when performing session control processing, a plurality of communication classes can be used by assigning a plurality of sessions to one communication flow.

It is a figure which shows the structure of the network system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the gateway apparatus in the network system shown by FIG. It is a figure which shows the message sequence regarding the component of a network in the case of communicating between the existing terminals 11 and 12 in Embodiment 1 of this invention. It is a figure which shows the structure of the network system which concerns on Embodiment 2 of this invention. It is a figure which shows the message sequence regarding the component of a network in the case of communicating between the existing terminals 11 and 12 in Embodiment 2 of this invention. It is a figure which shows the structure of the network system which concerns on Embodiment 3 of this invention. It is a figure which shows the message sequence regarding the component of a network in the case of communicating between the existing terminals 11 and 12 in Embodiment 3 of this invention. It is a figure which shows the message sequence regarding the component of a network in the case of communicating between the existing terminals 11 and 12 in Embodiment 4 of this invention.

Embodiment 1 FIG.
1 is a diagram showing a configuration of a network system according to Embodiment 1 of the present invention. In FIG. 1, gateway apparatuses 1 and 2 are associated with existing terminals 11 and 12 in user networks 101 and 102, which are existing IP networks that do not involve call control, and call control and call management based on SIP (Session Initiation Protocol). It exists between the call control network 100 having a plurality of priority classes, and performs call control processing at the time of communication between the existing terminals 11 and 12. Reference numeral 10 denotes an SIP server connected to the call control network 100.

  FIG. 2 shows the configuration of the gateway device in the network system shown in FIG. For example, the gateway device 1 transmits / receives packets to / from the outside of the gateway device, relays packets between two networks, monitors the traffic, and distributes the packets in the packet relay / distribution processing unit 21 and the packet relay / distribution processing unit 21. Priority identification unit 22 for identifying the priority of packets to be transmitted, session control unit 23 acting as a session control process for the call control network instead of the existing terminal 11, and session control unit in communication between the existing terminals 11 and 12 23 includes a session information table 24 that holds communication flow conditions and session control parameters to be subjected to session control. The gateway device 2 is configured in the same manner as the gateway device 1.

  Next, the operation will be described. The operation when communication is started from the existing terminal 11 to the existing terminal 12 will be described with reference to FIG. FIG. 3 shows a message sequence relating to network components when communication is performed between the existing terminals 11 and 12. At this time, it is assumed that the session information table 24 of the gateway device 1 holds two session control parameters having different priority classes for the communication flow between the existing terminals 11 and 12.

  First, the existing terminal 11 transmits a communication start packet indicating the start of the communication flow to the existing terminal 12 (step 301). When the gateway device 1 receives the communication start packet from the existing terminal 11 in the packet relay / distribution processing unit 21, the gateway device 1 holds the packet and notifies the session control unit 23 of the suspension. The session control unit 23 extracts a source IP address, a destination IP address, a protocol, a source port number, a destination port number, and the like from the received communication start packet, and different sessions of two corresponding communication classes from the session information table 24 A control parameter is obtained (step 302). The session control unit 23 generates two INVITE messages which are two call connection requests corresponding to the parameters obtained in step 302, and transmits them to the SIP server 10 (steps 303 and 304). At this time, it is assumed that the communication path established in step 303 has a higher priority class than the communication path established in step 304.

  When two communication paths are established on the call control network 100 by the session control unit 23, the relay processing of the communication start packet that has been suspended is resumed (step 305), and the communication flow between the existing terminals 11 and 12 thereafter The packet is relayed by the packet relay / distribution processing unit 21 (step 306). At this time, the packet addressed from the existing terminal 11 to the existing terminal 12 identifies the priority of the relay packet by the priority identifying unit 22 (step 307), and distributes the high priority packet to the communication path established in step 303 ( Step 308) distributes the low priority packet to the communication path established in Step 304 (Step 309). For example, in the case of videophone service traffic, it is conceivable to distribute voice packets to the high priority side and video packets to the low priority side.

  Similarly, the gateway device 2 also performs packet relay processing in the communication flow between the existing terminals 11 and 12 (step 306). At this time, the packet addressed from the existing terminal 12 to the existing terminal 11 is identified by the priority identifying unit 22 for the priority of the relay packet (step 307), and the high priority packet is distributed to the communication path established by the step 303 ( In step 308, the low priority packet is distributed to the communication path established in step 304 (step 309).

  When the communication flow between the existing terminals 11 and 12 is completed, the packet relay / distribution processing unit 21 of the gateway device 1 detects it (step 310) and notifies the session control unit 23 of it. The session control unit 23 generates a BYE message, which is a call disconnection request for disconnecting the communication path established in steps 303 and 304, and transmits them to the SIP server 10 (steps 311 and 312). As a result, the session is disconnected. In FIG. 3, “100 Trying” and “200 OK” indicate response codes for trial and request acceptance.

  As described above, when the start / end of communication between existing terminals is detected and the session control is performed in the relay device, a plurality of communication paths with different priority classes are established, and packets between existing terminals are set to the priority. Accordingly, it is possible to utilize a plurality of different priority classes for a single communication flow by allocating to each communication path accordingly. This also makes it possible to reduce the traffic amount of the high priority class in the network as compared with the case where a single communication flow is assigned to only a single high priority class.

  As a result, in the case of a TV phone service, video is disturbed due to packet loss or delay when the network is congested, but voice can be stably communicated, and only voice packets are sent to the high priority side. Can be expected to reduce the traffic volume of the high priority class.

  Further, as an example other than the TV phone service, a case where scalable CODEC (COder DECoder) is applied in video communication can be considered. In this case, packets for the lowest rate are assigned to the high priority side, and packets for the higher rate exceeding the lowest rate are assigned to the low priority side. As a result, even when the network is congested, the video quality for the minimum rate is guaranteed, and higher quality video communication can be expected when the network is not mixed.

  In the above embodiment, the case where SIP is used as the session control protocol has been described. Similarly, it is only necessary to be able to control and manage sessions on the IP network, such as H.323 and MEGACO.

  In the above embodiment, a plurality of sessions of different communication classes are used in the same network, but each session may be physically established on a different network.

  In addition, as a communication between existing terminals in the above-described embodiment, cases of TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) can be considered. In the case of TCP, a new communication flow start by a new TCP connection can be identified by a SYN packet, and the end of the flow can be identified by a FIN packet or an RST packet. In the case of UDP, the start of a new communication flow is identified from the source IP address, the destination IP address, the source port number, and the destination port number, and the end is identified when there is no packet of the communication flow for a certain period of time. be able to. Similarly, other protocols may be used as long as the start / end of communication of an existing terminal can be recognized by a gateway device acting as a session control.

  Furthermore, in the above-described embodiment, two different communication class sessions are associated with a single communication flow. However, each of three or more different communication class sessions can be identified in packet priority identification. It can be similarly applied by identifying corresponding to the communication class and distributing the packet accordingly.

Embodiment 2. FIG.
The first embodiment described above is intended for networks that require session control for all different communication classes. Next, an embodiment in which a network that requires session control and an unnecessary network are combined. Indicates. That is, in the second embodiment, as a communication path to be distributed, a communication path on a network with call control and a communication path on a network without call control are combined. Control for distributing priority packets to communication paths on the network with call control and distributing low priority packets to communication paths on the network without call control will be described.

  FIG. 4 shows the configuration of the network system according to the second embodiment of the present invention. In FIG. 4, the same components as those of the first embodiment shown in FIG. As a new code, 400 indicates a network such as the Internet that does not involve best-effort call control.

  Next, the operation will be described. The operation when communication is started from the existing terminal 11 to the existing terminal 12 will be described with reference to FIG. FIG. 5 shows a message sequence related to network components when communication is performed between the existing terminals 11 and 12. At this time, the gateway devices 1 and 2 have the configuration shown in FIG. 2, and the session information table 24 of the gateway device 1 holds session control parameters corresponding to the communication flow between the existing terminals 11 and 12. Suppose that

  First, the existing terminal 11 transmits a communication start packet indicating the start of the communication flow to the existing terminal 12 (step 501). When the packet relay / distribution processing unit 21 receives a communication start packet from the existing terminal 11, the gateway device 1 holds the packet and notifies the session control unit 23 of the packet. The session control unit 23 extracts a source IP address, a destination IP address, a protocol, a source port number, a destination port number, and the like from the received communication start packet, and obtains a corresponding session control parameter from the session information table 24 (step 502). The session control unit 23 generates an INVITE message that is a call connection request corresponding to the parameter obtained in step 502 and transmits it to the SIP server 10 (step 503). At this time, it is assumed that the communication path established in step 503 has a priority class with guaranteed quality.

  When the communication path is established on the call control network 100 by the session control unit 23, the relay process of the communication start packet that has been suspended is resumed (step 504), and the packet in the communication flow between the existing terminals 11 and 12 thereafter is The packet relay / distribution processing unit 21 performs relay processing (step 505). At this time, the packet addressed to the existing terminal 12 from the existing terminal 11 identifies the priority of the relay packet by the priority identifying unit 22 (step 506), and the high priority packet is established on the call control network 100 by step 503. (Step 507), and low-priority packets are assigned to the best effort network 400 (step 508). For example, in the case of videophone service traffic, it can be considered that voice packets are assigned high priority to the call control network 100 and video packets are assigned low priority to the best effort network 400.

  Similarly, the gateway device 2 also performs packet relay processing in the communication flow between the existing terminals 11 and 12 (step 505). At this time, the packet addressed to the existing terminal 11 from the existing terminal 12 identifies the priority of the relay packet by the priority identifying unit 22 (step 506), and the high priority packet is established on the call control network 100 by step 503. The low priority packets are distributed to the best effort network 400 (step 508).

  When the communication flow between the existing terminals 11 and 12 is completed, the packet relay / distribution processing unit 21 of the gateway device 1 detects it (step 509) and notifies the session control unit 23 of it. The session control unit 23 generates a BYE message, which is a call disconnection request for disconnecting the communication path established in step 503 (step 510), and transmits it to the SIP server 10. Thereby, the session established on the call control network 100 is disconnected.

  As described above, when connected to a network that requires session control and an unnecessary network at the same time, the quality is guaranteed when the start / end of communication between existing terminals is detected and session control is performed on the relay device. By establishing a communication channel and distributing packets between existing terminals to each network according to their priority, it is possible to simultaneously use a quality assurance network and a best effort network for the communication flow. It becomes. This also makes it possible to reduce the amount of traffic to the quality assurance network as compared with the case where all the communication flows are distributed only to the quality assurance network.

  As a result, in the case of the above-mentioned TV phone service, video is disturbed due to packet loss or delay when the network is congested, but voice can be stably communicated, and only voice packets are sent to the quality assurance network. The effect of reducing the amount of quality assurance traffic in the network can be expected.

  In the above embodiment, the physically different networks exist as the quality assurance type network and the best effort type network. However, these two networks may exist logically in the same network.

Embodiment 3 FIG.
In the third embodiment, the transmission side gateway device performs address conversion by different NAPT (Network Address Port Translation) for each communication path, and the reception side gateway device transmits packets that pass through all communication paths in the same communication flow. An embodiment in which rewriting is performed so as to be recognized by a packet will be described.

  FIG. 6 shows a configuration of a network system according to the third embodiment of the present invention. In FIG. 6, the same parts as those of the first embodiment shown in FIG. As a new code, 600 indicates a call control network having a plurality of priority classes with call control and call management by SIP as in the call control network 100, and 60 indicates a SIP server connected to the call control network 600. Here, the IP addresses in the user networks 101 and 102 are private addresses, and it is assumed that the gateway devices 1 and 2 perform address conversion processing by NAPT during communication with the outside.

  Next, the operation will be described. The operation when communication is started from the existing terminal 11 to the existing terminal 12 will be described with reference to FIG. FIG. 7 shows a message sequence relating to network components when communication is performed between the existing terminals 11 and 12. At this time, the gateway devices 1 and 2 have the configuration shown in FIG. 2, and the session information table 24 of the gateway device 1 has two different call control networks on the communication flow between the existing terminals 11 and 12. It is assumed that the session control parameter is held.

  First, the existing terminal 11 transmits a communication start packet indicating the start of the communication flow to the existing terminal 12 (step 701). When the gateway device 1 receives the communication start packet from the existing terminal 11 in the packet relay / distribution processing unit 21, the gateway device 1 holds the packet and notifies the session control unit 23 of the suspension. The session control unit 23 extracts a source IP address, a destination IP address, a protocol, a source port number, a destination port number, and the like from the received communication start packet, and a session on a different call control network corresponding to the session information table 24 A control parameter is obtained (step 702). The session control unit 23 generates INVITE messages that are two call connection requests corresponding to the parameters obtained in step 702, and transmits them to the SIP servers 10 and 60 (steps 703 and 704). At this time, in order to associate two INVITE messages, an identification parameter is included in the SDP (Session Description Protocol) of the INVITE message.

  When two communication paths are established on the call control networks 100 and 600 by the session control unit 23, the relay processing of the communication start packet that has been put on hold is resumed (step 705), and the communication between the existing terminals 11 and 12 thereafter is performed. Packets in the flow are relayed by the packet relay / distribution processing unit 21 (step 706). Packets addressed from the existing terminal 11 to the existing terminal 12 are identified by the priority identifying unit 22 for the priority of the relay packet (step 707), and are distributed to the communication paths established by the steps 703 and 704 (steps 708 and 709). . At this time, the gateway device 1 performs relay by replacing the transmission source IP address of the packet transmitted to the communication path by the NAPT process with the IP address of the gateway device 1 on the call control networks 100 and 600, respectively.

  In steps 708 and 709, the gateway device 2 that has received the packet from the communication path on the call control networks 100 and 600 transfers the packet addressed to the port number assigned to the terminal 12 to the terminal 12 after NAPT conversion. At this time, the packet from the communication path in step 708 rewrites the destination IP address and port number with the IP address and port number of the corresponding terminal 12. The packet from the communication path in step 709 is the destination IP address and port number of the corresponding terminal 12 IP address and port number, and the source IP address and port number of the gateway apparatus 1 on the communication path in step 708 are also shown. Rewrite the source IP address and source port number. As the transmission source IP address and port number of the communication path in step 708, values obtained from the value in the SDP of the INVITE message at the time of the call control request in step 703 are used. Thereby, in the terminal 12, the packet of the flow is recognized as a packet from the transmission source IP address and the transmission source port number of the communication path in Step 708.

  Similarly, the gateway device 2 also performs packet relay processing in the communication flow between the existing terminals 11 and 12 (step 706). Packets addressed from the existing terminal 12 to the existing terminal 11 are identified by the priority identifying unit 22 for the priority of the relay packet (step 707) and distributed to the communication path established by steps 703 and 704 (steps 708 and 709). . At this time, the gateway apparatus 2 performs relay by replacing the transmission source IP address of the packet transmitted to the communication path in steps 708 and 709 by the NAPT process with the IP address of the gateway apparatus 2 on the call control networks 100 and 600, respectively. The processing of the gateway device 1 that receives a packet from the communication path on the call control networks 100 and 600 is the same as that of the gateway device 2.

  When the communication flow between the existing terminals 11 and 12 is completed, the packet relay / distribution processing unit 21 of the gateway device 1 detects it (step 711) and notifies the session control unit 23 of it. The session control unit 23 generates a BYE message, which is a call disconnection request for disconnecting the communication path established in steps 703 and 704, and transmits them to the SIP servers 10 and 60 (steps 712 and 713). As a result, the session is disconnected.

  As described above, when the start / end of communication between existing terminals is detected and the session control is performed in the relay device, communication paths are established on a plurality of different networks, and between different IP addresses and port numbers by NAPT conversion. Even when using a communication path, it is possible to utilize multiple different networks for a single communication flow by performing conversion so that the terminal can recognize it as a single communication flow at the receiving side relay device. It becomes.

  In the above embodiment, a case where different IP addresses are used on two physically different call control networks has been described, but a plurality of IP addresses may be used on the same network.

  In the above embodiment, the case where NAPT conversion is performed in the gateway device has been described. However, it is only necessary to associate two calls for the same communication flow, and NAPT conversion is performed in the call control network, and the same session establishment destination. However, the same applies when the source IP address and port number change for each session.

Embodiment 4 FIG.
The configuration of the network system according to the fourth embodiment of the present invention is the same as that of the first embodiment shown in FIGS. In the fourth embodiment, when the ACK bit is set in the TCP header of the relay packet between the existing terminals, the session control unit 23 delays the packet including only the TCP header from which the data portion of the relay packet is deleted. An embodiment in which data is transferred to a communication channel with a small number will be described.

  Next, the operation will be described. The operation when TCP communication is started from the existing terminal 11 to the existing terminal 12 will be described with reference to FIG. FIG. 8 shows a message sequence related to network components when TCP communication is performed between the existing terminals 11 and 12. At this time, it is assumed that the session information table 24 of the gateway device 1 holds two session control parameters having different priority classes for the communication flow between the existing terminals 11 and 12.

  First, the existing terminal 11 transmits a SYN packet indicating the start of the TCP connection to the existing terminal 12 (step 801). When the gateway device 1 receives the SYN packet from the existing terminal 11 in the packet relay / distribution processing unit 21, the gateway device 1 holds the packet and notifies the session control unit 23 of the suspension. The session control unit 23 extracts a source IP address, a destination IP address, a protocol, a source port number, a destination port number, and the like from the received SYN packet, and performs session control with different two communication classes corresponding from the session information table 24. A parameter is obtained (step 802). The session control unit 23 generates two INVITE messages, which are two call connection requests corresponding to the parameters obtained in step 802, and transmits them to the SIP server 10 (steps 803 and 804). At this time, it is assumed that the delay of the communication path established in step 803 is smaller than the delay of the communication path established in step 804.

  When two communication paths are established on the call control network 100 by the session control unit 23, the relay processing of the communication start packet that has been put on hold is resumed (step 805), and in the communication flow between the existing terminals 11 and 12 thereafter. The packet is relayed by the packet relay / distribution processing unit 21 (step 806). At this time, the packet addressed from the existing terminal 11 to the existing terminal 12 is identified as a relay packet by the priority identifying unit 22 (step 807), and when the ACK (ACKnowledgement) bit is set in the TCP header, The packet consisting only of the TCP header from which the data part of the relay packet is deleted is transferred to the communication path established in step 803 (step 808), and the original relay packet is transferred to the communication path established in step 804 (step 809).

  Similarly, the gateway device 2 also performs packet relay processing in the communication flow between the existing terminals 11 and 12 (step 806). At this time, the packet addressed from the existing terminal 12 to the existing terminal 11 is identified by the priority identifying unit 22 (step 807). When the ACK bit is set in the TCP header, A packet consisting only of the TCP header from which the data part is deleted is transferred to the communication path (step 808), and the original relay packet is transferred to the communication path (step 809).

  When the TCP connection between the existing terminals 11 and 12 is completed, the packet relay / distribution processing unit 21 of the gateway device 1 detects it (step 810) and notifies the session control unit 23 of it. The session control unit 23 generates a BYE message, which is a call disconnection request for disconnecting the communication path established in steps 803 and 804, and transmits them to the SIP server 10 (steps 811 and 812). As a result, the session is disconnected.

  As described above, when detecting the start / end of a TCP connection between existing terminals and acting as session control in the relay device, a plurality of communication paths with different delays are established, and a packet consisting only of ACK is copied to reduce the delay time. By transferring through a small communication path, the apparent RTT from the terminal is reduced, thereby improving the TCP throughput between the terminals. In addition, this makes it possible to reduce the traffic amount of a class having a small delay time in the network as compared with a case where a single TCP connection is assigned only to a single class having a small delay time.

  1, 2 Gateway device, 10, 60 SIP server, 11, 12 Existing terminal, 21 Packet relay / distribution processing unit, 22 Priority identification unit, 23 Session control unit, 24 Session information table, 100, 600 Call control network, 101 , 102, 400 User network without call control.

Claims (8)

In a packet relay method in a network system that includes a gateway device that exists between an existing terminal and a call control network and that performs call control processing during packet communication between existing terminals,
Establish multiple communication paths with different priority classes for a single communication flow between existing terminals,
Identify the priority of communication packets between existing terminals,
A packet relay method characterized by allocating a communication path to be relayed according to the priority of an identified packet. The packet relay method according to claim 1,
As a communication path to be distributed, a communication path on a network with call control and a communication path on a network without call control are combined,
A packet relay method characterized by distributing a high priority packet to a communication path on a network with call control, and distributing a low priority packet to a communication path on a network without call control. In the packet relay method according to claim 1 or 2,
A packet characterized in that a transmission side gateway device performs address conversion using a different NAPT for each communication path and rewrites a packet that has passed through all communication paths to be recognized as a packet of the same communication flow in the reception side gateway apparatus. Relay method. In the packet relay method according to any one of claims 1 to 3,
A packet characterized in that when an ACK bit is set in a TCP header of a relay packet between existing terminals, a packet consisting only of a TCP header from which the data portion of the relay packet is deleted is transferred to a communication path with a small delay. Relay method. A gateway device that exists between an existing terminal and a call control network, and that performs call control processing during communication between existing terminals,
A packet relay / distribution processing unit that performs packet relay / distribution processing;
A priority identifying unit for identifying a priority of a packet relayed by the packet relay / distribution processing unit;
A control unit acting as a call control process with the call control network,
The control unit establishes a plurality of communication paths with different priority classes for a single communication flow between existing terminals, and identifies and identifies the priority of communication packets between existing terminals by the priority identifying unit. A gateway device that distributes a communication path to be relayed according to the priority of a packet. The gateway device according to claim 5,
As a communication path to be distributed, a communication path on a network with call control and a communication path on a network without call control are combined,
The gateway device characterized in that the control unit distributes high-priority packets to communication paths on a network with call control, and distributes low-priority packets to communication paths on a network without call control. The gateway device according to claim 5 or 6,
A gateway apparatus characterized in that, on the transmission side, address conversion based on a different NAPT is performed for each communication path, and on the reception side, a packet that has passed through all the communication paths is rewritten to be recognized as a packet of the same communication flow. In the gateway apparatus of any one of Claim 5-7,
When the ACK bit is set in the TCP header of the relay packet between the existing terminals, the control unit transfers the packet including only the TCP header from which the data portion of the relay packet is deleted to a communication path with a small delay. The gateway apparatus characterized by this.

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