JP4001044B2 - Packet receiving method and packet receiving apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to data reception using a packet communication network. In particular, the present invention provides a packet-type terminal that receives and reproduces video / audio data in real time using UDP (User Datagram Protocol) via a communication network in which packet bit errors cannot be avoided. The present invention relates to a receiving method and a receiving apparatus capable of suppressing disturbance of reproduced video / audio that is undesirable for a viewer even if it occurs, and particularly relates to a MAC layer protocol.
[0002]
[Prior art]
Conventionally, when a packet loss or packet bit error of a UDP packet occurs, a method for compensating for missing data by requesting retransmission from the receiving side to the transmitting terminal and retransmitting the lost data at the transmitting terminal is known. (For example, refer to Patent Document 1).
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 2001-136195
[Problems to be solved by the invention]
However, in the conventional compensation method for the UDP packet, a retransmission mechanism is added to the UDP that does not have a retransmission mechanism, so that there is an advantage that it can be completely compensated except for problems related to retransmission delay, but the missing data is retransmitted. Therefore, there is a problem that complicated control is required, and it is not possible to realize it only by the reception terminal, and the transmission terminal also needs a retransmission mechanism.
[0005]
In a packet communication network, communication protocols are hierarchized, and an OSI (Open Systems Interconnection) reference model defined by ISO (International Organization for Standardization) is often used to describe protocols. Here, the features of UDP / IP / Ethernet (R) will be described in comparison with the OSI reference model.
[0006]
UDP is a protocol located in the transport layer (fourth layer) in the OSI reference model, and is an unreliable communication that does not have a retransmission mechanism for packet loss or packet bit error. Since protocol processing can be executed at a higher speed than TCP (Transmission Control Protocol) having a retransmission mechanism in the protocol, its use is widespread in streaming distribution in which video and audio data is received and reproduced simultaneously.
[0007]
IP is a protocol located in the network layer (third layer) in the OSI reference model, and plays a role of sending data from the transmitting terminal to the receiving terminal beyond the node (packet relay device), but there is no compensation for sure delivery A protocol that provides unreliable communication.
[0008]
The Ethernet (R) protocol is a protocol located in the data link layer (second layer) in the OSI reference model. A protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address is called a MAC (Media Access Control) protocol, and Ethernet (R) is one of the MAC layer protocols. In addition, there are a MAC layer protocol for wireless communication and a MAC layer protocol for ATM (Asynchronous Transfer Mode). The physical address is also called a MAC address. Ethernet (R) also defines electrical characteristics and connectors of communication media classified in the physical layer of the OSI reference model, but the description is omitted because it is not related to the present invention.
[0009]
Each layer packet includes a header portion for storing control information and a payload for storing data to be transmitted. A UDP packet is composed of a UDP header and a UDP payload. The IP layer is one layer below the UDP layer, and is composed of an IP header and an IP payload, and a UDP packet is stored in the payload. Ethernet (R) is one layer below the IP layer, and is composed of an Ethernet (R) header and an Ethernet (R) payload, and an IP packet is stored in the payload.
[0010]
Here, the maximum packet size is stipulated in the protocol of each layer, and if the packet size of the upper layer exceeds the maximum packet size of the lower layer at the time of transmission, it is divided into multiple packets to fit within the maximum packet size of the lower layer Is done. This division is called a fragment, and the divided packet is called a fragment packet.
[0011]
The maximum packet size for UDP and IP is 65535 octets, and the maximum payload size for Ethernet® is 1500 octets. For this reason, when the packet size of an IP packet storing a UDP packet in the payload exceeds 1500 octets, the UDP packet is divided into a plurality of IP packets that are 1500 octets or less. Here, the first fragment packet has a UDP header, but the second and subsequent fragment packets have no UDP header. The transmission / reception terminal identifies the communication channel of the packet using the IP address and the port number of the UDP header. The second and subsequent fragment packets do not have a UDP header, but in the non-fragmented packet, the IP header ID is set to a different value for each IP packet, whereas in the fragment packet, the IP header ID is the same in the fragment packet. Since the UDP header can be known from the first packet of the same fragment using the ID, the communication channel of the second and subsequent fragment packets can be identified.
[0012]
According to such a UDP / IP protocol specification, when a bit error or loss occurs in the first packet of a fragment, the UDP header of the same fragment packet cannot be known, so the communication channel of the packet cannot be identified, and the fragment 2 Packets after the first are discarded.
[0013]
On the other hand, when video / audio data is transmitted by UDP, since the size of the video / audio data is generally larger than the maximum payload size of Ethernet (R), fragments often occur. Therefore, when a bit error occurs or the packet exceeds the default packet size, and the first packet of the fragment is discarded by the MAC layer protocol, not only the first packet but also the second and subsequent fragment packets are included. A large amount of data was discarded, and there was a problem that the video / audio reproduction was greatly disturbed.
[0014]
The present invention solves such a problem. In a packet communication network where a bit error of a packet cannot be avoided, an additional protocol is not required for a transmitting terminal, and when a bit error occurs in a leading packet of a fragment, An object of the present invention is to realize a packet receiving method and a packet receiving apparatus capable of suppressing disturbance of reproduction of video and audio even when a long packet exceeding a predetermined packet length of the protocol is received.
[0015]
[Means for Solving the Problems]
In order to solve the above-described problem, a packet reception method according to the present invention (Claim 1) includes a video / audio data determination step, and even when a check bit error occurs, a packet is discarded without being discarded. Communicate to the upper protocol execution step. With this configuration, if a packet in which a bit error occurs transmits video / audio data, the video / audio data can be transmitted to the upper protocol execution step.
[0016]
The packet reception method according to the present invention (Claim 2) includes a long packet determination step and a packet transmission step for transmitting a packet to an upper layer when a long packet is detected. Even when a long packet is received, the packet is received. The packet is transmitted to the upper protocol execution step without being discarded. With this configuration, if the long packet is transmitting video / audio data, the video / audio data can be transmitted to the upper protocol execution step.
[0017]
The packet reception method according to the present invention (Claim 3) includes an upper header extraction step for extracting a header of a protocol higher than the MAC layer, and transmits the header of the higher layer protocol to the upper protocol execution step. With this configuration, even when a bit error occurs in the head packet of the fragment packet, it is possible to determine the attributes of the second and subsequent packets of the same fragment packet by extracting the upper header of the head packet. The second and subsequent packets can be used without being discarded.
[0018]
The packet reception apparatus according to the present invention (Claim 4) has video / audio data determination means, and transmits the packet to the higher-level protocol execution means without discarding the packet even when a check bit error occurs. With this configuration, if the check bit error packet is transmitting video / audio data, the video / audio data can be transmitted to the higher-level protocol execution means.
[0019]
The packet reception device according to the present invention (Claim 5) has a long packet determination means and a packet transmission means for transmitting the packet to an upper layer when a long packet is detected, and even when a long packet is received, The packet is transmitted to the upper protocol execution step without discarding the packet. With this configuration, if the long packet is transmitting video / audio data, the video / audio data can be transmitted to the upper protocol execution step.
[0020]
The packet reception device according to the present invention (Claim 6) has higher protocol extraction means for extracting a header of a protocol higher than the MAC layer, and transmits the header of the higher protocol to the higher protocol execution means. . With this configuration, even when a bit error occurs in the head packet of the fragment packet, it is possible to determine the attributes of the second and subsequent packets of the same fragment packet by extracting the upper header of the head packet. The second and subsequent packets can be used without being discarded.
[0021]
With this configuration, the method and apparatus described above can be realized only by the receiving terminal without requiring a special additional protocol for the transmitting terminal.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0023]
FIG. 4 is a diagram for explaining the overall image of the packet receiving method according to the first, second or third embodiment of the present invention.
[0024]
In FIG. 4, a MAC layer protocol execution step 100 executes a protocol in a MAC layer of a received packet, an upper protocol execution step 200 executes a protocol higher than the MAC layer, and a network layer protocol execution step 210 includes: The upper layer protocol execution step 200 executes the network layer protocol, and the transport layer protocol execution step 220 executes the transport layer protocol in the upper protocol execution step 200.
[0025]
FIG. 8 is a diagram for explaining the overall image of the packet reception device according to the fourth, fifth or sixth embodiment of the present invention.
[0026]
In FIG. 8, the MAC layer protocol execution means 400 is a means for executing a protocol in the MAC layer of a received packet, the upper protocol execution means 500 is a means for executing a protocol higher than the MAC layer, and the network layer protocol execution means 510 is The upper layer protocol execution unit 500 executes the network layer protocol, and the transport layer protocol execution unit 520 executes the transport layer protocol in the upper layer protocol execution unit 500.
[0027]
(Embodiment 1)
FIG. 1 is a diagram for explaining a packet receiving method according to Embodiment 2 of the present invention (Claim 1).
[0028]
In FIG. 1, a packet reception determination step 110 is a step of determining whether or not a packet has been received, a check bit determination step 111 is a step of determining whether or not a check bit of a received packet is normal, and a check bit error notification step 112 is A step of notifying the higher-level protocol execution step 200 that a check bit error has occurred, a video / audio data determination step 113 checks the headers of the MAC layer, IP layer, and UDP layer, and whether the received packet is transmitting video / audio data The packet transmission step 114 is a step for transmitting the received packet to the higher-level protocol execution step 200, and the end determination step 115 is a step for determining whether or not to end the operation.
[0029]
In the video / audio data determination step 113, the source IP address of the IP header matches the IP address of the video / audio data transmitting station, the destination IP address of the IP header matches the IP address of the own station, and the IP header The upper protocol field indicates UDP, the source port number of the UDP header matches the port number used by the video / audio data transmitting station to transmit the video / audio data, and the destination port number of the UDP header is the local station. If the port number matches the port number for receiving the video / audio data, the received packet is determined to be a video / audio packet.
[0030]
In the case of Ethernet (R), the total size of the Ethernet (R) header, the IP header, and the UDP header is 42 octets when there is no IP header option, so the ratio of the header to the maximum packet size of 1500 octets Is only 2.8%. The video / audio data is considered to be sufficiently large with respect to 1500 octets, and the payload size of the Ethernet (R) packet for transmitting the video / audio data is considered to be a large value as close to 1500 octets. Accordingly, the probability that an abnormality has occurred in the video / audio data is much higher than the probability that an abnormality has occurred in the header portion including the upper protocol when a check bit error occurs. In addition, the error occurrence part does not extend over the entire data of the payload, but it may occur for a part of the data. For this reason, if the video / audio data is processed by assuming that the header is normal without discarding the packet, the reproduced video / audio is less disturbed.
[0031]
According to this configuration, when the check bit error packet is received, the MAC layer also checks the IP layer and UDP layer headers to determine whether or not the data being transmitted is video / audio data. In the case of a voice packet, the packet can be transmitted to the upper protocol execution step without being discarded.
[0032]
(Embodiment 2)
FIG. 2 is a diagram for explaining a packet receiving method according to the second embodiment of the present invention (Claim 2).
[0033]
2, the same components as those in FIGS. 1 and 4 are denoted by the same reference numerals, and the description thereof is omitted. The long packet determination step 116 is a step for determining whether or not the received packet is a long packet, and the long packet notification step 117 is a step for notifying the upper protocol execution step 200 that a long packet has been received.
[0034]
According to such a configuration, when a long packet is received, the MAC layer checks the IP layer and UDP layer headers to determine whether or not the data being transmitted is video / audio data. In this case, the packet can be transmitted to the upper protocol execution step without being discarded.
[0035]
(Embodiment 3)
FIG. 3 is a diagram for explaining a packet receiving method according to the third embodiment of the present invention (Claim 3).
[0036]
The same components as those in FIG. 1 and FIG. The upper header extraction step 118 extracts a header higher than Ethernet (R), the upper header transmission step 119 transmits the extracted upper header to the upper protocol execution step, and the packet discard step 120 discards the packet. It is.
[0037]
According to such a configuration, the check bit error packet is not simply discarded, but the upper header is extracted and transmitted to the upper protocol execution step 200. Therefore, even when a bit error occurs in the top packet of the fragment, The upper protocol execution step 200 can determine the attributes of the second and subsequent packets.
[0038]
When a check bit error occurs, the upper header is extracted and the upper header is transmitted to the upper protocol execution step. However, the upper header is always extracted and transmitted regardless of the occurrence of the check bit error. May be.
[0039]
(Embodiment 4)
FIG. 5 is a diagram for explaining a packet receiving method according to the fourth embodiment of the present invention (claim 4).
[0040]
In FIG. 5, a check bit determination means 410 is a means for determining whether or not a check bit of a received packet is normal, a check bit error notification means 411 is a means for notifying the higher-level protocol execution means 500 that a check bit error has occurred, The video / audio data determination unit 413 checks the header of the transport layer from the MAC layer and determines whether or not the received packet is transmitting video / audio data. The packet transfer unit 412 sends the received packet to the higher-level protocol execution unit 500. It is a means to transmit.
[0041]
In the video / audio data determination means 413, the source IP address of the IP header matches the IP address of the video / audio data transmitting station, the destination IP address of the IP header matches the IP address of the own station, and the IP header The upper protocol field indicates UDP, the source port number of the UDP header matches the port number used by the video / audio data transmitting station to transmit the video / audio data, and the destination port number of the UDP header is the local station. If the port number matches the port number for receiving the video / audio data, the received packet is determined to be a video / audio packet.
[0042]
According to this configuration, when the check bit error packet is received, the MAC layer also checks the IP layer and UDP layer headers to determine whether or not the data being transmitted is video / audio data. In the case of a voice packet, it is possible to realize a device that transmits the packet to the upper protocol execution step without discarding the packet.
[0043]
(Embodiment 5)
FIG. 6 is a diagram for explaining a packet receiving method according to the fifth embodiment of the present invention (Claim 5).
[0044]
The same components as those in FIG. 5 and FIG. The long packet determination unit 414 is a unit that determines whether or not the received packet is a long packet, and the long packet notification unit 415 is a unit that notifies the upper protocol execution unit 500 that a long packet has been received.
[0045]
According to such a configuration, when a long packet is received, the MAC layer checks the IP layer and UDP layer headers to determine whether or not the data being transmitted is video / audio data. In this case, the packet can be transmitted to the upper protocol execution step without being discarded.
[0046]
(Embodiment 6)
FIG. 7 is a diagram for explaining a packet receiving method according to the sixth embodiment of the present invention (claim 6).
[0047]
The same components as those in FIG. 5 and FIG. Upper header extraction means 416 is means for extracting a header higher than Ethernet (R), and upper header transmission means 417 is means for transmitting the extracted upper header to upper protocol execution means.
[0048]
According to such a configuration, not only the packet is not transmitted to the upper protocol execution unit 500 for the check bit error packet, but also the upper header is extracted and transmitted to the upper protocol execution unit 500. Even when an error occurs, the upper layer protocol execution means 500 can determine the attributes of the second and subsequent packets.
[0049]
When a check bit error occurs, the upper header is extracted and the upper header is transmitted to the upper protocol execution step. However, the upper header is always extracted and transmitted regardless of the occurrence of the check bit error. May be.
[0050]
In the first to sixth embodiments, Ethernet (R) has been described as an example of the MAC layer protocol. However, the present invention may be applied to MAC layer protocols other than Ethernet (R).
[0051]
In the first to sixth embodiments, the method and apparatus have been described in which the Ethernet (R) header, IP header, and UDP header of a packet in which a check bit error has occurred are considered to be normal. Since there is a checksum for confirming the reliability of the received packet, the received packet and the upper header may be transmitted to the upper protocol execution step and the upper protocol execution means only when the IP header is correct using the checksum. Good.
[0052]
Further, although Embodiments 1 to 6 have been described independently, they may be used in combination.
[0053]
【The invention's effect】
As described above, according to the packet receiving method and the packet receiving apparatus of the present invention, in the packet communication network where the bit error of the packet cannot be avoided, the bit error of the leading packet of the fragment occurs without requiring an additional protocol at the transmitting terminal. In this case, even when a long packet, which is a packet having a size exceeding the protocol default, is received, a packet receiving method and a packet receiving device that can suppress the disturbance of the reproduced video and audio can be realized.
[Brief description of the drawings]
FIG. 1 is a flowchart of a packet receiving method according to a first embodiment of the present invention. FIG. 2 is a flowchart of a packet receiving method according to a second embodiment of the present invention. FIG. 4 is a flowchart of a packet receiving method according to the first to third embodiments of the present invention. FIG. 5 is a block diagram of a packet receiving apparatus according to the fourth embodiment of the present invention. FIG. 7 is a block diagram of the packet receiving apparatus according to the sixth embodiment of the present invention. FIG. 8 is a block diagram of the packet receiving apparatus according to the fourth to sixth embodiments of the present invention. Relationship between model hierarchy and UDP / IP / Ethernet (R)
110 Packet reception determination step 111 Check bit determination step 112 Check bit notification step 113 Video / audio data determination step 114 Packet transmission step 115 End determination step 116 Long packet determination step 117 Long packet notification step 118 Upper header extraction step 119 Upper header transmission step 120 Packet discard step 121 Packet transmission step 100 MAC layer protocol execution step 200 Upper layer protocol execution step 210 Network layer protocol execution step 220 Transport layer protocol execution step 410 Inspection bit determination means 411 Inspection bit error notification means 412 Packet transmission means 413 Video / audio data Determination means 414 Long packet determination means 415 Long packet notification means 416 Upper header extraction means 417 Upper header transmission means 400 MAC layer protocol execution means 500 Upper protocol execution means 510 Network layer protocol execution means 520 Transport layer protocol execution means

Claims (6)

A packet receiving method comprising: a MAC layer protocol executing step for receiving a packet from a packet communication network and executing a MAC (Media Access Control) layer protocol; and an upper protocol executing step for executing a higher layer protocol than the MAC layer. There,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution step,
A packet reception determination step for determining that a packet has been received;
A check bit determining step of determining whether or not a bit error has occurred in the received packet by using a check bit added to the received packet;
A check bit error notification step of notifying the upper protocol execution step of an error;
A header of a protocol higher than the MAC layer is inspected to determine whether or not the received packet is transmitting video / audio data, and the received packet is transmitted to the upper protocol execution step. Packet transmission step to
An end determination step for determining the end of operation,
The check bit error notification step notifies the check bit error to the upper protocol execution step when it is determined in the check bit determination step that a bit error has occurred in the received packet,
In the video / audio data determination step, when it is determined that the received packet in which the check bit error has occurred transmits video / audio data, the packet transmission step is executed, and when it is determined that video / audio data is not transmitted Is a packet receiving method characterized by executing an end determination step. A packet receiving method comprising: a MAC layer protocol execution step for receiving a packet from a packet communication network and executing a MAC layer protocol; and an upper protocol execution step for executing a higher layer protocol than the MAC layer,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution step,
A packet reception determination step for determining that a packet has been received;
A long packet determination step of determining whether or not the packet size of the received packet exceeds a maximum packet size defined by a MAC layer protocol;
A long packet notification step of notifying the upper protocol execution step of reception of a long packet;
A video / audio data determination step of examining a header of a protocol higher than the MAC layer to determine whether the received packet transmits video / audio data;
A packet transmission step of transmitting the received packet to the upper protocol execution step;
An end determination step for determining the end of operation,
When the video and audio data determination step determines that the received packet determined to exceed the maximum size in the long packet determination step is transmitting video and audio data, the packet transmission step is executed. The packet reception method, wherein when the long packet determination step determines that the maximum size is not exceeded, the termination determination step is executed. A packet receiving method comprising: a MAC layer protocol execution step for receiving a packet from a packet communication network and executing a MAC layer protocol; and an upper protocol execution step for executing a higher layer protocol than the MAC layer,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution step,
A packet reception determination step for determining that a packet has been received;
A check bit determining step of determining whether or not a bit error has occurred in the received packet by using a check bit added to the received packet;
An upper header extraction step for extracting a header of a protocol higher than the MAC layer;
An upper header transmission step for transmitting the upper header extracted in the upper header extraction step to the upper protocol execution step;
A packet discarding step for discarding the received packet;
A packet transmission step of transmitting the received packet to the upper protocol execution step;
An end determination step for determining the end of operation,
When it is determined in the check bit determination step that a bit error has occurred, the upper header extraction step, the upper header transmission step, and the packet discard step are executed,
The packet receiving method, wherein if the bit error is not determined in the check bit determining step, the packet transmitting step is executed. A packet receiving apparatus comprising: a MAC layer protocol executing means for receiving a packet from a packet communication network and executing a MAC layer protocol; and an upper protocol executing means for executing a higher layer protocol than the MAC layer,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution means,
Check bit determining means for determining whether or not a bit error has occurred in the received packet using the check bit added to the received packet;
Check bit error notification means for notifying the upper protocol execution step of a bit error;
Video / audio data determination means for examining a header of a protocol higher than the MAC layer and determining whether the received packet is transmitting video / audio data;
A packet transmission step for controlling transmission of the received packet to the higher-level protocol execution means,
The check bit determination means outputs a check bit error signal to the packet transmission means when a bit error occurs in the received packet,
When the check bit error notification means receives a check bit error signal from the check bit determination means, the check bit error notification means notifies the check bit error to the higher-level protocol execution means,
The video / audio data determination means outputs a signal for determining whether or not the received packet is video / audio data to the packet transmission means,
The packet transmission means transmits the received packet to the higher-level protocol execution means when the received packet has a check bit error or a check bit error has occurred and is video / audio data. A characteristic packet receiving apparatus. A packet receiving apparatus comprising: a MAC layer protocol executing means for receiving a packet from a packet communication network and executing a MAC layer protocol; and an upper protocol executing means for executing a higher layer protocol than the MAC layer,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution means,
Long packet determination means for determining whether the packet size of the received packet exceeds the maximum packet size defined by the MAC layer protocol;
Long packet notification means for notifying the upper protocol execution means of long packet reception;
Video / audio data determination means for examining a header of a protocol higher than the MAC layer and determining whether the received packet is transmitting video / audio data;
Packet transfer means for transferring the received packet to the higher-level protocol execution means,
The long packet determination means outputs a long packet reception signal to the packet transmission means when the received packet is a long packet,
When the long packet notification unit receives a long packet reception signal from the long packet determination unit, the long packet notification unit notifies the upper protocol execution unit of long packet reception,
The video / audio data determination means outputs a signal for determining whether or not the received packet is video / audio data to the packet transmission means,
The packet transmission device, wherein the packet transmission means transmits the reception packet to the higher-level protocol execution means when the received packet is not a long packet or is a long packet and video / audio data. A packet receiving apparatus comprising: a MAC layer protocol executing means for receiving a packet from a packet communication network and executing a MAC layer protocol; and an upper protocol executing means for executing a higher layer protocol than the MAC layer,
The MAC layer protocol is a protocol that defines a method for accessing a communication medium and realizes communication between adjacent nodes using a physical address;
In the MAC layer protocol execution means,
Check bit determining means for determining whether or not a bit error has occurred in the received packet using the check bit added to the received packet;
Upper header extraction means for extracting a header of a protocol higher than the MAC layer;
Upper header transmission means for transmitting the upper header extracted by the upper header extraction means to the upper protocol execution means;
Packet transmission means for controlling transmission of the received packet to the higher-level protocol execution means,
The check bit determination means outputs a check bit error signal to the packet transfer means and the upper header transfer means when a bit error occurs in the received packet,
The upper header transmission means transmits the upper header to the upper protocol execution means when a check bit error signal is received from the check bit determination means,
The packet transmission device, wherein the packet transmission means transmits the received packet to the higher-level protocol execution means when a check bit error signal is not received from the check bit determination means.

Images