JP2000286893A - Router - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a router in a network to warrant freshness of information in the case of live transmission of continuos media such as video data via a mobile communication means. SOLUTION: The dialup router is provided with a wait time measurement means 6 that measures a wait time in a buffer of each packet received from a terminal on the Internet, a maximum wait time setting means 7, a comparison means 7 that compares the wait time with the maximum wait time, and a packet abort means 9 and is configured such that the router aborts a packet whose wait time exceeds the maximum wait time. Furthermore, a transmission terminal provides importance of information to each packet, by which the maximum wait time setting means of the dialup router changes the setting value accordingly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network router device for live transmission of continuous media such as video via mobile communication means such as a personal handy phone system (PHS).

[0002]

2. Description of the Related Art Conventionally, there is a router that interconnects networks to which communication terminals are connected, receives a packet transmitted from a certain network, stores the received packet in a storage unit, and relays the packet to another network. In particular, from circuit-switched networks such as ISDN and PHS to LAN
Routers that interconnect storage-and-switch networks such as the Internet and the Internet are called dial-up routers.

With respect to routers and dial-up routers, in order to absorb the difference in transmission capacity of interconnected networks, control network congestion, and secure the communication service quality required by users, the processing order of received packets is controlled. And packet discard control at the time of congestion are considered. For example, in Japanese Patent Application Laid-Open No. Hei 6-502012, in order to transmit a high-priority packet with a small delay time, packets transmitted to a dial-up router within a predetermined period are transmitted according to the priority of the packet. A technique for rearranging the order is disclosed. Further, Japanese Patent Application Laid-Open No. Hei 7-135512 discloses a technique for discarding a packet according to the priority assigned to the packet when the network is congested.

However, these are intended for data communication, and special consideration is given to transmission of continuous media in which information having a temporal structure is continuously generated, such as video and audio. Absent. For example, rearranging the order of transmission of packets is obviously not effective for continuous media. In addition, packet discarding according to the priority or the like at the time of congestion cannot always reduce the delay time of continuous media. In particular, in the case of continuous transmission of live media, it is necessary to reduce the delay time. That is, it is important how to guarantee the elapsed time since the information is generated, that is, the so-called freshness of the information. However, the conventional technology cannot always guarantee freshness of continuously generated live media information in a dial-up router.

[0005] Such a problem becomes conspicuous when accessing the Internet via mobile communication. For example, in Internet access by PHS, retransmission control (for example, PIAFS) is applied between a mobile terminal including a wireless communication section and a dial-up router. Therefore, when live media is continuously transmitted from a terminal on the Internet to a mobile terminal, retransmission occurs frequently due to the deterioration of the wireless communication environment and interruption of communication due to handover, and the waiting time at the dial-up router increases. However, the delay time increases.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is directed to a network router for live transmission of continuous media such as video via mobile communication means such as a PHS. The purpose is to guarantee the freshness of information in the device.

[0007]

According to the present invention, claim 1 is:
In a router device connected to a plurality of networks, a temporary storage means for temporarily storing packets received from terminals connected to the networks, and a storage time measurement for measuring a time stored in the temporary storage means Means,
Maximum storage allowable time setting means for setting a maximum storage allowable time that can be stored in the temporary storage means, and comparison means for comparing the measured time with the maximum storage allowable time are provided, and the storage time is determined by the comparison means. Packets whose time measured by the measuring means exceeds the maximum allowable storage time are discarded.

According to a second aspect of the present invention, in the terminal according to the first aspect, the terminal connected to the network assigns importance of information to a packet to be transmitted, and gives the maximum storage allowable time setting means based on the importance. It is characterized in that a maximum allowable storage time is set.

According to a third aspect of the present invention, in the terminal according to the second aspect, the terminal connected to the network transmits information to the packet in accordance with a correlation between video frames applied at the time of compression encoding of the video information to be transmitted. And assigning a maximum allowable storage time to the maximum allowable storage time setting means based on the importance.

A fourth aspect of the present invention is characterized in that, in the third aspect, the importance of a packet having video information to which a bidirectional predictive encoding method is applied is reduced.

A fifth aspect of the present invention is characterized in that, in the third aspect, the importance of a packet having video information to which an intra-frame encoding method is applied is increased.

A sixth aspect of the present invention is characterized in that, in the first aspect, when a packet is discarded, there is provided means for notifying the terminal connected to the network of the discard.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a block diagram of a dial-up router according to a first embodiment of the present invention.

In FIG. 1, 1 and 2 indicate two networks interconnected by a dial-up router 10. In particular, in the present embodiment, the network 1
Is assumed to be a LAN or the Internet, and the network 2 is assumed to be an ISDN or a PHS connected via the ISDN. Reference numeral 3 denotes a packet reception processing unit for receiving and processing packets via the network 1; 4, a queue for temporarily storing the received packets; 5, a packet transmission process for transmitting the packets stored in the queue 4 via the network 2. Department. In order to transmit a packet received from the network 2 to the network 1, there is a packet reception processing unit on the network 2 side, a packet transmission processing unit on the network 1 side, and a queue between both.
Here, the description is omitted. In a dial-up router, a plurality of networks are often connected on the side of the network 2 assuming ISDN. However, only one is shown here.

On the other hand, 6 is a waiting time measuring means for measuring the waiting time of each packet received from the network 1 in the dial-up router 10, and 7 is the maximum waiting time for setting the maximum waiting time of the packet in the dial-up router 10. The setting unit 8 compares the standby time of each packet measured by the standby time measuring unit 6 with the time set by the maximum standby time setting unit 7.
Reference numeral 9 denotes a packet discarding unit for discarding an arbitrary packet stored in the queue 4.

In the present embodiment configured as described above, the present invention operates as follows.

When a packet is received by the packet reception processing unit 3 via the network 1, the dial-up router 10 stores the packet in the queue 4, and measures the standby time of the packet in the dial-up router by the standby time measuring means. Start measurement. In addition,
The method of calculating the standby time may use the difference between the current time and the arrival time of the packet. When the packet transmission processing unit 5 reads a packet from the queue 4 and performs transmission processing,
The packet transmission processing unit 5 sends the standby time measurement unit 6
Request the end of the measurement of the waiting time of the corresponding packet.

Here, in the maximum standby time setting means 7, the maximum standby time of a packet in the dial-up router is set in advance. Then, the comparing unit 8 compares the value of the standby time of each packet from the standby time measuring unit 6 with the value indicated by the maximum standby time setting unit 7, and the standby time of the packet exceeds the maximum standby time. If the packet is detected, the packet discarding unit 9 is requested to discard the packet. In response to this, the packet discarding unit 9 discards the corresponding packet from the queue 4. Upon receiving the discard request, the packet discarding unit 9 may discard the corresponding packet from the queue 4 immediately, or may discard the packet at the timing when the corresponding packet is read from the packet transmission processing unit 5. Further, the packet discarding unit 9 requests the standby time measuring unit 6 to end the measurement of the standby time of the corresponding packet at the same time when the packet is discarded.

By controlling in this way, the standby time of the packet in the dial-up router can be made equal to or less than the value indicated by the maximum standby time setting means 7, and the freshness of the information can be guaranteed.

FIG. 2 is a block diagram of a dial-up router according to a second embodiment of the present invention.

In FIG. 2, reference numeral 11 denotes means for extracting, from each packet, the importance of the packet assigned to each packet by the transmitting terminal. Reference numeral 7 denotes a maximum standby time setting means for setting a maximum standby time of the packet in the dial-up router 10, and a plurality of maximum standby times can be set according to the importance of the packet. How the transmitting terminal assigns importance information to each packet is arbitrary.

In the present embodiment configured as described above, the present invention operates as follows.

When a packet is received by the packet reception processing unit 3 via the network 1, the dial-up router 10 stores the packet in the queue 4, and measures the standby time of the packet in the dial-up router by the standby time measuring means. Start measurement. At the same time, the packet importance extracting means 11 extracts the importance given to the packet by the transmitting terminal.

Here, in the maximum standby time setting means 7, a plurality of maximum standby times of the packet in the dial-up router are set in advance according to the importance of the packet. Then, the comparing unit 8 compares the value of the standby time of each packet from the standby time measuring unit 6 with the maximum standby time setting unit 7
Is compared with the value corresponding to the importance of the packet, and when it is detected that the standby time of the packet exceeds the maximum standby time, the packet discarding means 9 is
Requests that the packet be dropped. In response to this, the packet discarding unit 9 discards the corresponding packet from the queue 4.

With such control, freshness of information can be guaranteed in accordance with the importance of the packet. For example, when transmitting compressed video information such as MPEG, it is conceivable to assign importance to each packet according to the correlation between video frames applied at the time of compression encoding. In the compressed video information, each encoded video frame information (picture) is an I picture (Intra: intra-coded picture) and a P picture (Predictive: inter-frame predictive coding) according to the correlation between frames. Pictures) and B pictures (Bi-directional: pictures that have been bidirectionally coded). Since the B picture is not referred to when decoding other pictures, it does not disturb the image quality during reproduction even if it is lost. However, the I picture or P picture is referred to when decoding other pictures. The image quality is disturbed during playback. Therefore, although the B picture may be discarded more frequently, it is conceivable that the priority of reducing the delay time is prioritized and the importance of the packet is reduced, that is, the maximum waiting time in the dial-up router is reduced. Conversely, since I-pictures have a large effect on image quality when discarded, the delay time may be somewhat large. It is conceivable to increase the maximum waiting time in the router. When a packet is discarded by the dial-up router, the image quality may be disturbed. Therefore, the transmission terminal may be notified that the dial-up router has discarded the packet.

[0027]

According to the present invention, when live media such as video is transmitted live by accessing the Internet via mobile communication means, packets with a large delay time are transmitted to a dial-up router. By discarding, freshness of information can be guaranteed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 3 packet reception processing unit 4 queue 5 packet transmission processing unit 6 standby time measurement unit 7 maximum standby time setting unit 8 comparison unit 9 packet discarding unit 10 dial-up router 11 packet priority extraction unit

Continued on front page F-term (reference) 5K030 HA08 HB02 HB17 HC09 HD03 JL01 JT09 KA02 KA19 LA07 LC18 5K033 CB08 CC01 DA19 DB18 EC03 5K067 AA13 AA41 BB04 BB21 CC08 DD52 EE02 EE16 GG06 HH23 9A05 BB10JJ04 CC04 DD01

Claims (6)

[Claims] In a router device connected to a plurality of networks, a temporary storage means for temporarily storing a packet received from a terminal connected to the network, and a time stored in the temporary storage means. A storage time measuring means for measuring; a maximum allowable storage time setting means for setting a maximum allowable storage time which can be stored in the temporary storage means; and a comparing means for comparing the measured time with the maximum allowable storage time. A router device for discarding a packet whose time measured by the storage time measuring means by the comparing means exceeds the maximum allowable storage time. 2. The terminal according to claim 1, wherein the terminal connected to the network assigns importance of information to a packet to be transmitted, and the maximum storage allowable time setting means sets the maximum storage allowable time based on the importance. A router device for setting a time. 3. The terminal according to claim 2, wherein the terminal connected to the network assigns importance of the information to the packet in accordance with a correlation between video frames applied at the time of compression encoding of the video information to be transmitted. And setting the maximum allowable storage time in the maximum allowable storage time setting means based on the degree of importance. 4. The router device according to claim 3, wherein the importance of a packet having video information to which the bidirectional predictive coding method is applied is reduced. 5. The router device according to claim 3, wherein the importance of a packet having video information to which the intra-frame coding method is applied is increased. 6. The router device according to claim 1, further comprising means for notifying a terminal connected to the network when the packet is discarded.