JP2003143219A - Relaying apparatus and method for packet switch communication network - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively utilize a network resource by preventing congestion of a network when transmission of real time contents is controlled in a packet switch network. SOLUTION: A controller 120 of the relaying apparatus of this invention inhibits a module device 131 at a lower-order layer receiving a data packet to produce a request signal with respect to re-transmission of the data packet or limits a rate of the request signal with respect to re-transmission of the data packet by the module device 131 at the lower-order layer. The controller 120 transmits a control signal to reduce a transmission rate of a re-transmission request signal of a data packet to a receiver side terminal when the network is in slight congestion, transmits a control signal to inhibit the re-transmission request of the data packet to the receiver side terminal when the network is in heavy congestion, and transmits a control signal to permit the re- transmission request of the data packet to the receiver side terminal when no congestion takes place in the network.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to the field of methods for coordinating traffic in packet switched data communication networks. In particular, the present invention relates to a relay device and a relay method for a packet switching communication network for performing the processing according to the above method.

[0002]

2. Description of the Related Art Recently, real-time content transmission via packet switched networks, especially the Internet, has developed as one of the main technical fields. One feature of data streaming over the Internet is:
Even if a packet is formatted according to the Internet Protocol (IP), it can traverse smaller networks with very different data link technologies. Various such techniques provide functionality for data retransmission and / or acknowledgment. However, usually these techniques are not fully utilized in end-to-end transmission schemes. Instead,
Retransmission and acknowledgment mechanisms are only used to ensure reliable transmission of data streams. Most of today's real-time content transmitted over the Internet consists of audio / video (AV) streams. Such an AV stream does not require a highly reliable connection-oriented service. In particular, the occasional discard of data packets can be tolerated. In contrast, the use of retransmissions and / or acknowledgments to ensure reliable transmission of such streams often results in variable delays that are unacceptable for AV streaming. As a result, A
Many V-streaming transport mechanisms ignore the retransmission and / or acknowledgment capabilities provided by the underlying network layer.

Real-time content is typically streamed so that the content is divided into smaller logical units of data called content objects and that need to be presented to the application as a whole. Each of these content objects may be fully contained in a single data packet or may span multiple data packets. A suitable example is AV streaming, where the content object means the data from one video frame or the audio signal from one subband. These Content Objects may have certain dependencies between them. Simply stated, this means that when a particular object is not received, some objects cannot be decrypted and presented to the user or to applications at higher layers.
One example of such a dependency is the most common speech-
It is specified in the Motion Picture Experts Group (MPEG) standard, a format for streaming moving pictures. In the MPEG standard, video frames are independent frames (I-frames), forward-predicted frames (P-frames) and bi-predicted frames (B-frames).
-Frame). I-frames are video frames that can be independently decoded. A P-frame is a video frame in which only the difference between the current frame and the preceding frame is encoded, so in order to successfully decode the P-frame, the frame preceding it must be available. I won't. A B-frame is a video frame in which the difference between the current frame and its preceding and subsequent frames is encoded, so in order to successfully decode a B-frame, the frames before and after it are Both need to be available. Therefore, it can be said that the data packet containing the content of the P-frame depends on the data packet containing the content from the preceding frame. Similarly, a data packet containing content from a B-frame may be said to be dependent on a data packet containing content from the preceding frame and the next frame.

In addition, real-time content typically has an explicit presentation deadline. Content objects that are not transmitted by the presentation deadline are said to have no presentation value. These features have made real-time content incompatible with traditional retransmission / acknowledgement mechanisms. This allows differentiated services (Dif
fServ), multi-protocol label switching (MPLS), and more virtual private networks (VPNs) that employ different quality of service (QoS) strategies such as marking fields in other IP packets, resulting in It enables good quality of service for high priority data paths. However, some denial of se
Managing rvice attacks) has become an increasingly difficult task. This requires network planning and complex network monitoring to ensure that traffic attacks on network components do not disrupt connection and transport services of low priority data paths.

For reliable transmission of data over a network, the Internet is constructed with redundant routes to compensate for any failures at the network and / or physical layers, and reliability is a concern of transport. It can be achieved in layers, for example with TCP / IP. If a packet is lost during transmission, a signal requesting retransmission is automatically generated. As a result, in real-time applications, every time a packet is lost or delayed, wasteful retransmission of lost / delayed packets will automatically occur after their individual usefulness has expired. I have something to do.

To ensure successful packet transmission,
A method of detecting erroneous reception of transmitted data and generating corresponding retransmission request signals for these data packets is proposed in US Pat. No. 6,163,869. In order to achieve error-free transmission, the excess transmission capacity or bandwidth needs to be continuously available during the transmission of data. To ensure that the nominal data throughput remains constant without being affected by retransmissions, even if data packets are received in error.
The receiver only requests retransmissions as long as it is possible to connect with the excess capacity (bandwidth) available on average over time.

A method of selectively retransmitting data packets for efficient streaming of multimedia packets in computer networks has been proposed in US Pat. No. 5,918,002. This method checks the feasibility of a retransmission from the receiver side before the receiver actually requests the retransmission of a given data packet. If after re-transmission the packet is found to have no value, then the packet is not re-transmitted and is simply discarded. This prevents the network from wasting resources on unnecessary retransmissions.

An invention that addresses the problem of packet transmission order is proposed in US Pat. No. 5,896,402. It uses the frame number assigned to the transmitted frame and some special processing at the sender and the receiver to achieve ordering of the data in transmission and retransmission.

[0009]

Although the prior art techniques described above help solve some of the problems in transmitting data in an error-free manner, these prior art techniques are primarily intended for reception. It operates on the side and is configured to transmit generic data. The following discusses some of the problems that these prior art methods either did not address or could not solve.

[0010] Streaming of real-time contents requires a service having a different property compared to conventional data transmission (for example, file transmission). This results in a stream transmission method for real-time content transmission that ignores various capabilities provided by the underlying network layer, such as retransmission and acknowledgment mechanisms. Therefore, an apparatus and method configured to utilize such a mechanism to enhance the performance of real-time content transmission and optimally utilize network resources is desirable.

However, retransmissions and acknowledgments cause transmission delays. Moreover, excessive retransmission request signals and acknowledgment signals tend to place an additional load on communication networks, which are often already congested. Thus allowing effective use of retransmissions and acknowledgments,
It is desirable to control the transmission of retransmission request and acknowledgment signals so that the use of such a mechanism does not aggravate the network situation.

It is also possible to cache selected data streams in a network element in order to improve the transmission quality of service of any class of data service which travels through the network element and is supported by the network. It is necessary to Further, it is desirable to include a configuration that eliminates denial of service attacks on low priority data services while the network is congested.

It is further desirable to provide a new method for providing tandem caching (cascade caching) of content or near real-time content at intermediate network components. This method reduces the chance of large range data retransmissions when the distance between the content source and the content destination is long. It is desirable for network hops to effectively reduce the use of scarce network resources by reducing the number of retransmissions and reducing the distance of retransmissions.

[0016] Further, traffic is mitigated by temporarily storing the data stream in the network component, and the network is formed in the intermediate network component, the content originator network node, and the content terminal device network node. It is desirable to provide a means to smooth the utility of resources.

Still further, the network node enables the caching of the most used data content in order to redistribute it to the user terminals that are closest to said network node and used the most used data. is necessary. This allows
Problems are solved in broadcast modes where data is being broadcast by flooded communication links starting from the source of the content. Furthermore, it is desirable to provide the necessary mechanism to perform selective broadcast and eliminate the possibility that broadcast data may reach untargeted terminals or viewers.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a relay device and a relay method capable of preventing congestion of a real-time content when controlling transmission of real-time content in a packet switching communication network and effectively using network resources.

[0017]

A relay device for a packet-switched communication network according to an aspect of the present invention is used in a packet-switched communication network, and transmits content-specific transmission to a terminal device that receives a data packet. A relay device for controlling the data packet, wherein the terminal device detects a data packet reception error and automatically transmits a signal requesting retransmission of the data packet, and within a predetermined timeout period. And a means for voluntarily transmitting a signal requesting retransmission of the data packet when the reception of the data packet fails, the relay device comprises retransmission request control means, and the retransmission request control means, To prohibit the terminal device receiving the data packet from generating a signal requesting retransmission of the data packet. And means for controlling, characterized in that the terminal device that receives the data packet and means for controlling so as to limit the rate for generating a signal requesting a retransmission of the data packet.

In the relay device, the retransmission request control means sends the data packet to the terminal device that receives the data packet when the congestion level of the network is equal to or more than a predetermined first threshold value. A control signal for prohibiting a request for retransmission is transmitted, the degree of network congestion is smaller than the first threshold value, and the first
Is greater than or equal to a second threshold value smaller than the threshold value, the control signal for reducing the transmission rate of the signal requesting retransmission of the data packet is transmitted to the terminal device receiving the data packet. When the network congestion level is smaller than the second threshold value, by transmitting a control signal permitting requesting retransmission of the data packet to a terminal device receiving the data packet, In the packet switching communication network, traffic related to retransmission of a plurality of data packets in a plurality of data streams is adjusted.

Further, the relay device further comprises an acknowledgment control means for controlling the operation of the terminal device receiving the data packet transmitted from the relay device, transmitting an acknowledgment signal for the data packet,
The acknowledgment control means transmits a control signal for prohibiting the transmission of the acknowledgment signal to the terminal device receiving the data packet when the congestion level of the network is equal to or higher than a predetermined first threshold value. , The degree of network congestion
When it is smaller than the first threshold and equal to or larger than a second threshold smaller than the first threshold, a transmission rate of an acknowledgment signal to the terminal device receiving the data packet. And a control signal for permitting the terminal device receiving the data packet to transmit an acknowledgment signal when the network congestion level is smaller than the second threshold value. By transmitting, the traffic associated with transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switching communication network is adjusted.

Furthermore, in the relay device, an outgoing data storage device that stores a plurality of data packets to be transmitted to the terminal device that receives the data packet, and a plurality of transmission data storage devices that are transmitted to the terminal device that receives the data packet. A retransmission data storage device for storing a copy of the data packet, and a first device from the terminal device for receiving the data packet.
Means for changing the timeout attribute of the data packet stored in the transmission data storage device in response to the request signal from the terminal device, and the second replay signal in response to the second request signal from the terminal device receiving the data packet. Transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switching communication network, further comprising means for changing a timeout attribute of a duplicate of a data packet stored in a transmission data storage device. It is characterized by adjusting traffic related to.

According to a relay method for a packet switched communication network according to an aspect of the present invention, for controlling content-specific transmission to a terminal device used in a packet switched communication network and receiving a data packet. And a step of automatically transmitting a signal requesting retransmission of the data packet, the terminal device detecting a data packet reception error, and receiving the data packet within a predetermined timeout period. When it fails, the step of voluntarily transmitting a signal requesting retransmission of the data packet, the relay device, the terminal device receiving the data packet, the signal requesting retransmission of the data packet. The step of controlling to prohibit the generation and the terminal device receiving the data packet. There characterized in that it comprises a step of controlling so as to limit the rate for generating a signal requesting a retransmission of the data packet.

In the relay method, when the network congestion level is equal to or higher than a predetermined first threshold value, a control for prohibiting the terminal device receiving the data packet from requesting the retransmission of the data packet. Transmitting a signal, and when the network congestion level is equal to or higher than a second threshold value that is smaller than the first threshold value and smaller than the first threshold value, the data packet is transmitted. Transmitting a control signal for reducing the transmission rate of the signal requesting retransmission of the data packet to the receiving terminal device;
The step of transmitting a control signal for permitting a request for retransmission of the data packet to a terminal device receiving the data packet when the packet-switched communication is performed. Coordinating traffic associated with retransmission of multiple data packets in multiple data streams in the network.

Further, in the relay method, the method further includes the step of controlling the operation of the terminal device receiving the data packet transmitted according to the relay method, transmitting an acknowledgment signal for the data packet, the step comprising: When the congestion level is equal to or higher than a predetermined first threshold value, a step of transmitting a control signal for prohibiting the transmission of an acknowledgment signal to the terminal device receiving the data packet, and the network congestion level, First above
Is smaller than the first threshold value and is equal to or larger than a second threshold value smaller than the first threshold value, the transmission rate of the acknowledgment signal is reduced to the terminal device receiving the data packet. Transmitting a control signal, and transmitting a control signal that permits the terminal device receiving the data packet to transmit an acknowledgment signal when the congestion degree of the network is smaller than the second threshold value. And adjusting traffic for transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switching communication network.

Further, in the relay method, the step of storing a plurality of data packets to be transmitted to the terminal device receiving the data packet in an outgoing data storage device, and the step of storing the plurality of data packets to the terminal device receiving the data packet. Storing a duplicate of the data packet in the retransmitted data storage device, and time-out of the data packet stored in the outgoing data storage device in response to a first request signal from a terminal device receiving the data packet. Changing the attribute and changing the timeout attribute of the duplication of the data packet stored in the retransmitted data storage device in response to a second request signal from the terminal device receiving the data packet. By further including, a plurality of data in the packet switching communication network. And adjusting the traffic related to the transmission and / or retransmission of a plurality of data packets in the stream.

Further, the relay device stores an outgoing data storage device for storing a plurality of data packets transmitted to the packet switching communication network and a copy of the plurality of data packets transmitted to the packet switching communication network. It further comprises a retransmitted data storage device and means for associating a timeout period with each data packet transmitted to the packet switched communication network.

Further, in the above-mentioned relay method, in the packet-switched communication network, there is provided a method of adjusting traffic related to transmission of a plurality of data packets in a plurality of data streams, wherein each incoming data packet is stored in the outgoing data storage. Inserting into a device and sending a single content object grouped into one or more data packets in the originating data storage device at scheduled intervals using a predetermined scheduling algorithm A step of moving a copy of the plurality of transmitted data packets from the originating data storage device to the retransmitted data storage device; associating a timeout period with the transmitted data packet; Requesting belief Retransmitting the plurality of data packets from the retransmitted data storage device upon receipt of a message, and removing the transmitted data packet from the retransmitted data storage device when the timeout period expires. And when a signal requesting retransmission of a data packet not found in the retransmission data storage device is received, the loss of the data packet is detected as a data packet so as to prevent unnecessary generation of the signal requesting retransmission. Transmitting a control signal for notifying the terminal device that receives

Still further, in the above relaying method, the traffic associated with transmitting a plurality of data packets in a plurality of data streams in the packet switched communication network using the additional ability to selectively acknowledge the data packets. A step of inserting each incoming data packet into the outgoing data storage device, and scheduling the plurality of data packets in the outgoing data storage device using a predetermined scheduling algorithm. Transmitting at a fixed interval, moving a copy of the transmitted data packet from the originating data storage device to the retransmit data storage device, associating a timeout period with the transmitted data packet, Request resend A step of retransmitting the plurality of data packets from the retransmitted data storage device when receiving a signal, and the retransmitted data from the retransmitted data storage device when an acknowledgment signal for the data packet is received. Removing data packets, removing the transmitted data packets from the retransmitted data store when the timeout period expires, and retransmitting data packets not found in the retransmitted data store. When receiving the request signal, transmitting a control signal for notifying the terminal device receiving the data packet of the loss of the data packet so as to prevent unnecessary generation of the signal requesting retransmission. It is characterized by

The relay method is also a relay method for adjusting traffic relating to transmission and / or retransmission of a plurality of data packets in a plurality of data streams in the packet switching communication network, wherein Then, a presentation deadline can be derived that indicates when the data packet needs to be transmitted by it and thereafter the transmission of the data packet has no presentation value. Inserting a data packet into the outgoing data storage device, and the plurality of data packets in the outgoing data storage device,
Transmitting at a scheduled interval using a predetermined scheduling algorithm, moving a copy of the transmitted data packet from the source data store to the retransmit data store, and transmitting the duplicate Associating a time-out period with the data packet, the time-out period being derived so that the presentation deadline of the data packet is not exceeded, and when the signal requesting the retransmission is received, the time-out period is transmitted from the retransmitted data storage device. Retransmitting the data packet, removing the transmitted data packet from the retransmitted data storage device when the timeout period expires, and retransmitting a data packet not found in the retransmitted data storage device Requires When receiving the signal, the step of transmitting a control signal notifying the terminal device receiving the data packet of the loss of the data packet so as to prevent unnecessary generation of the signal requesting retransmission, and the data. Removing the plurality of data packets from the source data store and the retransmitted data store when the presentation deadline of the packet expires.

Further, in the relay method, the additional ability to selectively acknowledge data packets is used to transmit and / or retransmit multiple data packets in multiple data streams in a packet switched communication network. A relay method for adjusting traffic related to transmission, wherein for each data packet, the above-mentioned data packet needs to be transmitted by it, and after that, the timing at which the transmission of the data packet does not have a presentation value is performed. The presentation deadline shown can be derived, the relay method inserting each incoming packet into the outgoing data store,
A step of transmitting the plurality of data packets in the source data storage device at scheduled intervals using a predetermined scheduling algorithm, and a copy of the transmitted data packet from the source data storage device in the retransmitted data packet. Moving to a storage device, associating a time-out period with the transmitted data packet, the time-out period being derived so that the presentation deadline of the data packet is not exceeded, and requesting the retransmission Retransmitting the data packet from the retransmitted data storage device when receiving a signal to transmit the transmitted data packet from the retransmitted data storage device when an acknowledgment signal for the data packet is received. Remove Removing the transmitted data packet from the retransmitted data storage device when the time-out period expires; and receiving a signal requesting retransmission of a data packet not found in the retransmitted data storage device. Then, a step of transmitting a control signal for notifying the terminal device receiving the data packet of the loss of the data packet so as to prevent unnecessary generation of a signal requesting retransmission, and a step of transmitting the plurality of data packets. Removing the plurality of data packets from the originating data store and the retransmitted data store when the presentation deadline has expired.

Further, in the above-mentioned relay method, the control signal is transmitted by means for superimposing in a plurality of data packets (transmitted by piggyback method), or the control signal is transmitted as an independent control packet. To do.

Still further, in the above relay method, there is provided a relay method for adjusting traffic related to transmission and / or retransmission of a plurality of data packets in a plurality of data streams in the packet switching communication network,
Multiple data packets in a given same data stream are interdependent so that the loss of one data packet may render several other packets in the same data stream worthless. And the relay method, when receiving a signal requesting retransmission of a data packet, if the requested data packet is available, until the retransmission of the requested data packet is successful. Delaying the transmission of all other data packets in the same data stream depending on the requested data packet and requesting retransmission of the data packet not found in the retransmission data store Other signal in the same data stream depending on the requested data packet A step of discarding all data packets and transmitting a control signal for notifying the terminal device receiving the data packets of the loss of the data packets so as to prevent unnecessary generation of a signal requesting retransmission. It is characterized by including.

The packet-switched communication network has means for removing data packets identified by the control mechanism from the outgoing data store and releasing the corresponding memory block for reuse. Means for removing a data packet from the retransmitted data store and releasing the corresponding memory block for reuse.

The relay method is also a relay method for adjusting traffic related to retransmission of a plurality of data packets in a plurality of data streams in the packet switching communication network, wherein a corresponding discard request signal is sent from a terminal device. When received, the step of removing the data packet being accessed by the terminal device from the outgoing data storage device; and when the corresponding discard request signal is received from the terminal device, the data packet being accessed by the terminal device is received. Removing from the retransmitted data storage device.

Further, the relay method is a relay method for adjusting traffic related to retransmission of a plurality of data packets in a plurality of data streams in the packet switching communication network, the relay method being dependent on the removed data packet. The method further comprises removing a plurality of data packets from the originating data storage device and removing a plurality of data packets that depend on the removed data packets from the retransmitted data storage device.

Furthermore, in the relay method, there is provided a method of adjusting traffic related to retransmission of a plurality of data packets in a plurality of data streams in the packet switching communication network, wherein a transmission stop control signal is received from a terminal device. And a means for removing all data packets whose destination is the terminal device in the transmission data storage device, and a transmission stop control signal from the terminal device when the destination is the terminal device in the retransmission data storage device. And a means for removing all data packets that are connected to the terminal device, when receiving a connection closing control signal from the terminal device, remove all data packets whose destination is the terminal device in the transmission data storage device and the retransmission data storage device. And means for doing so.

The above packet-switched communication network is configured so that when a plurality of terminal devices request the same data packet,
For each terminal, further comprising means for reusing the data packet stored in the retransmit data store for retransmission instead of moving the packet from the source data store to the retransmit data store. It is characterized by

Further, the packet switching communication network further comprises means for recording the number of retransmissions for a specific terminal device within a specific time period, and means for recording the number of retransmissions for a specific data source. Is characterized by.

According to the relay unit according to the aspect of the present invention, the relay unit caches the content in the specific node by using the transmission control, and the specific (plural) streams or (plural) data to be cached. When transmitting a flow from an upstream source, creating a new session for content-specific transmission control,
Or recovering the session being created,
Set multiple appropriate parameters for content-specific transmission controls, such as changing the timeout attribute above, and adjust multiple timing parameters for source content-specific transmission controls based on current input traffic conditions. And storing the content in a cache memory for further distribution of the content, and erasing the session after the caching session is complete.

According to the relay mechanism according to the aspect of the present invention, the incoming / outgoing traffic detector for detecting the traffic from the incoming link, the caching speed adjuster for controlling the input and output flows, and the outgoing call Control delayed session scheduler, data transfer, memory allocation, and deallocation of available memory to reschedule the passage of caching content from original or upstream sources The cache memory controller and the short-term memory for caching from the downloaded data stream for immediate transmission to the downstream node, thereby timing parameters for caching like the modification of the timeout attribute described above. Schedule Wherein the dynamically changing.

Further, according to the relay method according to another aspect of the present invention, based on the relay mechanism, the caching mechanism is cascade-connected at the hop of the network element between the source transmitting the content and the content terminal device. This reduces the peak bandwidth usage for redistributing the content to multiple content sink parties.

To solve the above problems, the present invention enables existing network architectures to use an apparatus or device that implements caching and transmission control mechanisms in each connected network component. The apparatus or device comprises means for controlling the transmission of retransmission request signals and acknowledgment signals, means for scheduling the retransmission of content objects and maintaining coherence of the content objects with respect to presentation deadlines and object dependencies. And a means for eliminating all content objects addressed to the terminal device that closed the connection in order to prevent unnecessary re-transmissions, and to deal with the situation where there are multiple requests for the same content. A means for reusing the content object in the retransmission, a means for recording the information in the packet when the retransmission occurs to provide statistical information about the transmission of the content object, and an intermediate network component, , The network components from which the content originates Both means for caching content in the network element where the content is terminated, means for re-determining the content download schedule based on traffic conditions in each network element, and both input and output ports of the network element Means for controlling the cache memory based on the state of traffic in
A means for cascading all intermediate network components between content sources and content sinks, and adaptive control of caching in the network components to service low priority data flows during short duration network congestion attacks. And means for eliminating the refusal.

[0042]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

A method of coordinating traffic associated with transmitting and retransmitting multiple data packets in multiple data streams in a communication network is disclosed below. In order to facilitate understanding of the present invention, terms used in the following description are defined as follows. A "packet (or data packet)" is a self contained unit of data in any possible format that can be transmitted over a data network. "stream"
Is a set of packets that are transferred in the network and that have a certain attribute in common. The “upper layer” and the “lower layer” do not necessarily have to be physically or logically higher or lower than the module device (relay device) for adjusting traffic. “Upper layer” refers to any entity (component) outside the module device that passes the data packet to the module device, and “lower layer” refers to the module device that receives the data packet from the module device. An entity outside. A “sending terminal device” is a terminal device in a network segment that sends data to a network. It does not have to be the source terminal device that originates the data content. The relay device of the present invention is a source (source) of a data stream path.
And is intended to be used on the terminal equipment along the path between the sink (termination). Therefore, it can be said that all terminal devices that are transmitting or pumping traffic to the network segment using the relay device of the present invention along this path are “transmitting side terminal devices”. Hereinafter, in the present embodiment, a terminal device that transmits a data packet to a relay device is referred to as a transmission-side terminal device.
It includes a source terminal device or other relay device. In the present embodiment, as an example thereof, an upper layer module device 130 is illustrated. A "reception side terminal device" is a terminal device in a network segment that receives data from the network. It need not be the actual desired ultimate recipient of the data stream.
In the present embodiment, a terminal device called “reception side terminal device” in a certain network segment may be a “sending side terminal device” for another connected network segment. Hereinafter, a terminal device that receives a data packet from the relay device of the present invention is referred to as a receiving side terminal device, which includes other relay devices or sink (destination) terminal devices. In the present embodiment, as an example thereof, a lower layer module device 131 is illustrated.
"Content object" refers to a logical string of data that can be presented as an individual unit. A "content object" may be contained entirely within one data packet or may span multiple data packets. In the present embodiment, both "content object" and "data packet" can be used interchangeably as meaning a content object, unless it is clearly specified that they are clearly different in context.

In the following description, for purposes of explanation, specific numbers, times, structures and other parameters are set forth in order to provide a thorough understanding of the present invention. However, it will be apparent to any person skilled in the art that the disclosed invention may be practiced without these specific details.

FIG. 1 is a block diagram illustrating a part of a network including the relay devices 1-1 to 1-N according to the embodiment of the present invention. The relay devices 1-1 to 1-N are general frameworks for traffic regulation that can be provided on arbitrary network elements (NE) such as gateways, routers, and bridges. The relay apparatus 1-1 executes a process of adjusting traffic related to transmission and retransmission of a data packet transmitted on a certain communication line, and the relay apparatuses 1-2 to 1-N also on another line. The above processing can be similarly performed on the data packet.

A source terminal device (not shown) for transmitting a data packet transmits a desired data packet, and the data packet is illustrated as an arbitrary number of relay devices (in FIG. 1, the upper layer module device 130). Relay device 1 according to the embodiment of the present invention.
Received at 1. Further, the relay device 1-1 reads the destination data embedded in the header part of the data packet,
The data packet is transmitted to the terminal device designated by the destination data. The data packet transmitted from the relay device 1-1 is further transmitted via an arbitrary number of relay devices (illustrated as the lower layer module device 131 in FIG. 1) and then designated as a destination. It is received by the terminal device (not shown).

The relay device 1-1 of the embodiment includes a receiving side interface 101, an outgoing data storage device 102, a packet scheduling algorithm device 103, a retransmission data storage device 104, and a retransmission control algorithm device 1.
05, the transmission side interface 106 and the controller 120. The packet scheduling algorithm device 103 manages input / output of data packets to / from the transmission data storage device 102, and the retransmission control algorithm device 105 manages input / output of data packets to / from the retransmission data storage device 104. Further, the controller 120 responds to the control signal coming from the upper layer module device 130 or the lower layer module device 131 in response to the packet scheduling algorithm device 1
03 and the operation of the retransmission control algorithm device 105.

In FIG. 1, an upper layer module device 1
30 supplies the data packet transmitted with respect to each data stream, and the supplied data packet is input into the receiving side interface 101 of the relay apparatus 1-1, for example. The reception side interface 101 separates the data packet into the data packet of the received data signal and the data packet of the control signal transmitted / received to / from the module device 130 of the upper layer, and the data packet of the data signal is separated. The data packet is transmitted to the transmission data storage device 102 via the data path 107, and the data packet of the control signal is transmitted to the controller 120 via the control signal path 113. The outgoing data storage device 102 stores the data packet of the data signal for each data stream, and the packet scheduling algorithm device 10
3. Wait for scheduling for transmission according to 3.
The packet scheduling algorithm device 103
Outgoing data storage device 102 via control signal path 117
Is selected and a data packet to be transmitted to the lower layer module device 131 is selected. The packet scheduling algorithm device 103 further retrieves the selected data packet from the outgoing data storage device 102 via the data path 108 and duplicates it, transmitting the original packet data via the data path 109, and the duplicated packet. The data is transmitted via the data path 110. One of the data paths 109, via the transmission-side interface 106, is used for the module device 13 of the lower layer for transmission output to the packet switching network.
Connected to 1. The other data path 110 is a retransmitted data storage device 1 for replicating transmitted data packets.
It is used to store in 04.

The transmitting side interface 106 includes the data packet of the data signal to be transmitted and the data of the control signal generated by the controller 120 for transmission to the lower layer module device 131 and transmitted through the control signal path 115. The packet is superposed and the superposed data packet is transmitted to the lower layer module device 131. The transmission side interface 106 also transmits the data packet of the control signal received from the lower layer module device 131 to the controller 120 via the control signal path 115.

The controller 120 processes all control signals (including retransmission request signals) that may have been transmitted by either the upper layer module device 130 or the lower layer module device 131 and processes accordingly. ,
Control packet scheduling algorithm device 103 via control signal path 114 and / or retransmit control algorithm device 105 via control signal path 116.
To control. That is, the controller 120 detects, for example, an error in a packet received from the upper layer module device 130 and detects the packet error.
To the lower layer module device 131, and a lower layer module device 131 a retransmission request signal relating to an error of the packet transmitted to the lower layer module device 131.
And control the retransmission of the corresponding packet received from.

The retransmission data storage device 104 stores the data packet of the duplicated data signal, and makes the retransmission control algorithm device 105 wait for scheduling. Retransmission control algorithm device 105, under the control of controller 120, searches retransmitted data storage device 104 via control signal path 118 and selects a data packet for retransmission. Retransmission control algorithm device 105 further retrieves the selected data packet from retransmission data storage device 104 via data path 111 and inserts it into outgoing data storage device 102 via data path 112.

The present invention is adapted for use in a packet switched communication network in which the underlying transport layer has the ability to automatically request retransmissions. This means that when the receiving terminal detects an error in the received data packet, or when the receiving terminal fails to receive the scheduled data packet, the receiving terminal receives a specific data packet. Means that it must be able to request the retransmission of the. In addition, the rate at which the receiving side terminal device can transmit the transmission request signal (for example, the time interval for transmitting the transmission request signal)
A mechanism for restricting the above needs to be provided to the transmitting side terminal device or an intermediate gateway (for example, the relay device 1-1). In particular, the sending terminal device or the intermediate gateway needs to be able to prohibit further transmission of a retransmission request signal by the receiving terminal device until the sending terminal device or the intermediate gateway removes the restriction.

FIG. 2 shows processing steps when the data packet to be transmitted is transmitted from the module device 130 of the upper layer. When the relay device 1-1 first receives the data packet in step 201, the relay device 1-1 proceeds to step 20.
At 2, it is determined which data stream the packet belongs to. Then, in step 203,
This data packet is inserted into the outgoing data storage device 102 related to the data stream. At the same time, in step 204, the packet scheduling algorithm device 103 is informed about this new insertion from the originating data store 102 and the actions necessary to schedule the scheduling of this packet are performed.

No assumptions have been made regarding how the data stream of the data packets is determined. Any one of ordinary skill in the art includes the use of source and / or destination addresses of data packets, parameters embedded in the data packets, or parameters transmitted with the data packet via a call to the function, but You will be able to recognize several different techniques for doing this, including but not limited to: In addition, no assumption is made about how to insert the data packet into the outgoing data store 102. It will be clear to anyone skilled in the art that the present invention can be used with any buffer management method.

The packet scheduling algorithm device 103 is transmitted to the network (may be contained in a single data packet alone or may be contained over multiple data packets). Sending data storage device 1
Select from 02 regularly. Regarding the selection criteria used by the packet scheduling algorithm device 103 when scheduling content objects,
No assumptions are made. It will be readily appreciated by one of ordinary skill in the art that the present invention can work with any selection criteria (eg, FIFO). FIG. 3 shows the processing steps of the scheduling for the transmission of a content object, which are performed by the packet scheduling algorithm device 103 when the content object is selected for transmission. Step 30
1, the controller 120 controls the packet scheduling algorithm device 103, and accordingly, the packet scheduling algorithm device 103.
Selects a Content Object for transmission from the Outgoing Data Store 102, and the subsequent step 302
At, the selected content object is retrieved from the outgoing data storage device 102. Step 303
At, the packet scheduling algorithm device 103 duplicates the data packet (s). The packet scheduling algorithm device 103 sends one copy to the lower layer module device 131 for sending to the network in step 304 and inserts another copy in the retransmitted data storage device 104 in step 305. . Then, step 306
Then, the controller 120 controls the retransmission control algorithm device 105, and accordingly, the retransmission control algorithm device 105 causes the retransmission data storage device 104 to input the data packet (s) to the retransmission data storage device 104. Packet time-out period (time-to-live timeo) that specifies the longest time that can remain in the storage device before being retrieved (ie, the "live time" before being removed from the retransmitted data storage device 104).
ut period) is associated with the data packet. In the case of a general data type stream, this timeout period can be set arbitrarily. The recommended time-out period is twice the round trip time of a data packet between the sending terminal device and the receiving terminal device. For types of data streams where each data packet has a unique presentation deadline, the time-out period should be chosen not to exceed this presentation deadline. Here, "presentation deadline" means
By that time, the data packet needs to be transmitted, and after that, the transmission of the data packet indicates the timing such that the data packet has no presentation value. The recommended timeout period is twice the round trip time between network components or the presentation deadline, whichever is shorter. In addition, when the presentation deadline of a data packet expires, the data packet needs to be removed from either the originating data store 102 or the retransmitted data store 104, depending on where it can be found. .

When the retransmission request signal is received from the receiving side terminal device, the controller 120 then operates the retransmission control algorithm device 105 in response to the request signal. No assumption is made about how the retransmission request signal is transmitted from the terminal device at the final receiving end. Any person skilled in the art can perform this by superimposing a signal of control information and a data signal (transmitting a request signal to a data packet by a piggyback method) or by controlling the request signal by an independent control signal. And / or will immediately recognize several methods including, but not limited to, sending as packets of feedback signals and / or acknowledgment signals.

FIG. 4 shows a flowchart of the response processing to the retransmission request signal, which is executed by the retransmission control algorithm device 105 when the retransmission request signal is received. In step 401, the controller 120
Receives a retransmission request signal from the lower layer module device 131, then in step 402 the controller 120 causes the retransmission control algorithm device 105 to
Cause the retransmitted data store 104 to be searched for the requested data packet P. Once the data packet P is found in step 403, the retransmission control algorithm unit 105 then retrieves the data packet P from the retransmission data store 104 in step 405 and sends it to the source data for retransmission in step 406. Storage device 1
02, and finally the packet scheduling algorithm device 103 is notified of this reinsertion in step 407. Packet scheduling algorithm device 1
03, the packet scheduling algorithm device 103 uses the transmission data storage device 10
2 by automatically detecting (without passing through the controller 120) or by the controller 120 controlling the control signal transmitted from the retransmission control algorithm device 105 via the control signal path 116. A method of transmitting to the packet scheduling algorithm device 103 via the signal path 114 may be used.

If the requested data packet P is not found in step 403, then in step 404,
The retransmission control algorithm device 105 uses the data packet P
Is notified to the controller 120, and the controller 120 notifies the receiving side terminal device via a data packet of the control signal. This step 4
The reason for executing 04 is to prevent the receiving side terminal device from repeatedly requesting retransmission of the same data packet P and thereby occupying valuable network resources. Instead of sending the requested data packet P directly to the lower layer module unit 131 for retransmission,
The reason for re-inserting the data packet P into the outgoing data storage device 102 is to satisfy the demand for controlling the bandwidth in the packet scheduling algorithm device 103. Since the retransmission of the data packet P occupies the network bandwidth, the requested data packet P needs to be subjected to the same scheduling process as in FIG. 3 again as if it were a newly transmitted packet. is there. To anyone skilled in the art, in the absence of bandwidth control there is generally no loss, and the packet scheduling algorithm device 103 only schedules the reinserted data packet P for immediate transmission. Would be obvious.

Data packets cannot be held in the retransmitted data storage device 104 indefinitely. The above-described timeout period associated with each data packet in retransmitted data store 104 serves as a method of removing the data packet from retransmitted data store 104. If the underlying transport mechanism is a network system that supports acknowledgments for transmitted data packets, the acknowledgment signal can be used as a trigger to remove the data packet from the retransmitted data store 104. . This is because it is not necessary to retransmit if the receiving terminal device has correctly received the data packet.

Certain data streams have the property of data packets that depend on other data packet (s) for successful decoding. That is, multiple data packets in a given same data stream are mutually related such that the loss of one data packet may render the transmission of several other packets in the same data stream worthless. Have a dependency. In such a situation, the packet scheduling algorithm device 103 can use a process that implements a more complex bandwidth control method that utilizes such packet dependencies. Embodiments of the present invention supplement and improve such flow control mechanisms by providing additional information about the transmission of data packets.

FIG. 5 shows the retransmission control algorithm device 10
5 is a packet scheduling algorithm device 103
6 is a flowchart showing a method for enhancing the operation of the above, showing a response process to a retransmission request signal in consideration of data packet dependency. These steps are such that multiple data packets have unique dependencies between each,
It is provided for data streams that belong to a given category. The steps 501 to 506 of FIG. 5 are basically the same as those of FIG.
Data packet P as in steps 401 to 406
Retransmission request signal is received. If the data packet requested to be retransmitted, for example data packet P, cannot be found in the retransmitted data storage device 104, in step 508 the retransmit control algorithm device 105 determines that the data packet P is lost. The packet scheduling algorithm device 103 is notified via 120. This means that the receiving terminal fails to receive the data packet P and therefore discards all data packets in the buffer memory of the outgoing data store 102 which are dependent on P for decoding. That is, the packet scheduling algorithm device 103 is notified that it is acceptable. On the other hand, if the data packet P is located in the retransmitted data storage device 104, it is retrieved from the retransmitted data storage device 104 in step 505 and reinserted in the outgoing data storage device 102 in step 506. Packet scheduling algorithm device 103
Is notified in step 507 that the data packet P has been reinserted into the data stream. In this case, the packet scheduling algorithm device 10
3 delays the transmission of all other data packets that depend on data packet P until data packet P is retransmitted.

The retransmission mechanism is arranged to provide a reliable transmission service. However, not all data streams require the transport layer to be highly reliable. In addition, most of the reason for the need to retransmit a data packet is network congestion rather than error in transmission. Sending a resend request signal and / or an acknowledgment signal puts more congestion on the already congested network. The embodiment of the present invention addresses this problem by controlling the rate at which the receiving side terminal device can transmit the retransmission request signal. The retransmission control algorithm device 105
Periodically, in a preferred embodiment often checks the information on the network congestion status provided by the packet scheduling algorithm device 103.
The packet scheduling algorithm device 103
It is in the best position to provide information on the congestion state of the network, since it is performing the operation of controlling bandwidth. As an example, when the outgoing data storage device 102 is almost completely occupied, the network congestion is interpreted, and when the outgoing data storage device 102 is almost empty, it is interpreted as indicating that the network is not congested. .

FIG. 6 shows a response process executed by the controller 120 in response to the retransmission request signal. First, in step 601, the controller 120 acquires information indicating the state of network congestion from the packet scheduling algorithm device 103. The "congestion degree" is used as the information indicating the congestion state of the network, and as an example of the detection method, by detecting how much of the memory area of the transmission data storage device 102 is occupied by data packets, Determine the degree of congestion. The controller 120 also determines whether the retransmission request signal is enabled or disabled in the reception terminal device and the transmission rate information of the retransmission request signal based on the data packet of the control signal transmitted from the reception terminal device. get. In step 602, if the controller 120 determines that the degree of congestion is such that the network is extremely congested (for example, 90% or more of the memory area of the transmission data storage device 102 is occupied by data packets). Then, in step 603, it is determined whether or not the transmission of the retransmission request signal is enabled in the receiving side terminal device. If YES in step 603, in step 604, by transmitting a control signal for disabling the transmission of the retransmission request signal to the receiving side terminal device,
The receiving side terminal device is suppressed from further transmitting the retransmission request signal, and the process ends. On the other hand, step 60
If NO in 3, the process ends. In step 602, it is determined that the network is not extremely congested, and in step 605 the network is slightly congested (for example, 50% or more and 90% or more of the memory area of the outgoing data storage device 102).
When it is determined that the number less than the above is occupied by the data packet), it is subsequently determined in step 606 whether the transmission of the retransmission request signal is enabled. If YES in step 606, in step 607, a control signal for limiting the transmission rate of the retransmission request signal transmitted by the receiving side terminal device to half the original value is transmitted to the receiving side terminal device, The process ends. On the other hand, if NO in step 606,
It ends as it is. In addition, if it is determined in step 605 that the network is not congested (for example, less than 50% of the memory area of the outgoing data storage device 102 is occupied by data packets), a retransmission request is issued in step 608. Determine if signal transmission is enabled. Y in step 608
In the case of ES, it is judged in step 609 whether or not the transmission rate of the retransmission request signal is smaller than the designated maximum value. In the case of YES in step 609, the transmission rate of the retransmission request signal is set in step 610. A control signal is sent to limit it to twice its original value. Thereby, the relay device 1-1 transmits the retransmission request signal to the receiving side terminal device at twice the original rate unless the transmission rate of the retransmission request signal exceeds the specified maximum value. Then, the processing ends. On the other hand, step 60
If NO in 9, the process ends. If NO in step 608, in step 611, a control signal for re-enabling the transmission of the retransmission request signal is transmitted to the receiving-side terminal device, and the process ends.

If the underlying transport layer provides a mechanism to control the rate at which acknowledgment signals can be sent, the retransmission request signal of FIG. 6 can be used to control the rate at which acknowledgment signals can be sent. The method similar to the case can be adopted. FIG. 7 is a flowchart showing this method, which is executed by the controller 120 and relates to the control processing of the transmission rate of the acknowledgment signal. First, in step 701, the controller 120 acquires information indicating the state of network congestion from the packet scheduling algorithm device 103. Controller 120
Also, based on the data packet of the control signal transmitted from the receiving side terminal device, the receiving side terminal device obtains the enabled or disabled state of the acknowledgment and the information of the transmission rate of the acknowledgment signal. Step 702
In the above, the controller 120 is in a state where the network is extremely congested with respect to the congestion degree (for example,
If it is determined that 90% or more of the memory area of the outgoing data storage device 102 is occupied by data packets), then in step 703, it is determined whether or not transmission of an acknowledgment signal is enabled in the receiving side terminal device. To judge. If YES in step 703, in step 704, by transmitting a control signal for disabling the transmission of the acknowledgment signal to the receiving terminal device, the receiving terminal device further transmits the acknowledgment signal. It is suppressed and the process ends. The acknowledgment signals whose transmission is suppressed may be set to be transmitted collectively, for example, at a predetermined large time interval. On the other hand, if NO in step 703, the process ends. In step 702, it is determined that the network is not extremely congested, and in step 705, the network is slightly congested (for example, 50% or more and less than 90% of the memory area of the outgoing data storage device 102 is If it is determined that the packet is occupied by the data packet), then step 70
At 6, it is determined if the transmission of the acknowledgment signal is enabled. If YES in step 706, in step 707, the control signal for limiting the transmission rate of the acknowledgment signal transmitted by the receiving side terminal device to half of the original value is transmitted to the receiving side terminal device, and the processing is performed. To finish. On the other hand, if NO in step 706, the process ends. Besides that, step 7
If it is determined at 05 that the network is not congested (eg, less than 50% of the memory area of the outgoing data store 102 is occupied by data packets), then transmission of an acknowledgment signal is enabled at step 708. It is determined whether or not it has been done. Step 708
If YES in step 709, it is determined in step 709 whether the transmission rate of the retransmission request signal is smaller than the specified maximum value. If YES in step 709, the transmission rate of the acknowledgment signal is set in step 710. By transmitting a control signal for limiting the original value to twice, the acknowledgment signal is transmitted to the receiving terminal device if the rate of transmission of the acknowledgment signal does not exceed the specified maximum value. The transmission is permitted at twice the rate, and the process ends. On the other hand, if NO in step 709, the process ends. Also, step 7
If NO in 08, in step 711,
A control signal for re-enabling the transmission of the acknowledgment signal is transmitted to the receiving side terminal device, and the processing is ended.

Various forms are possible in which the control signal limits the rate of transmission of the retransmission request signal and the acknowledgment signal. In the present embodiment, the present invention identifies two such methods. However, it will be clearly understood by one of ordinary skill in the art that other means of implementing a similar control mechanism are possible and that the invention includes the claims encompassing all such methods. Will be done.
One such method is to embed a control signal in the outgoing data packet. Most transmission schemes support in-band signaling so that control signals are superimposed on the data packets (transmitted in piggyback). Such a mechanism can be used to control the rate of transmission of retransmission request signals and / or acknowledgment signals. Another method is to send these control signals in another packet on the same or another channel.

FIG. 8 shows an embodiment of a possible implementation of the process of removing the data packet designated by the control mechanism (the receiving side terminal device and the controller 120 which has received the control signal from the receiving side terminal device). There is. In step 801, when a request signal for removing a specific data packet from the receiving terminal device arrives at the controller 120,
At step 802, the controller 120 instructs the packet scheduling algorithm device 103 to search the outgoing data storage device 102 for a data packet that matches the specified attribute.
Then, in step 803, the controller 120 determines whether or not the data packet is found, and if YES, in step 804, the packet scheduling algorithm device 103 removes the data packet from the outgoing data storage device 102, Frees the memory block that was occupied by the so that it can be reused. After the removal in step 804 is completed, or if NO in step 803, in step 805, the controller 120 causes the retransmission control algorithm device 105 to match the attribute specified in the retransmission data storage device 104. Instruct to search for data packets. Then, in step 806, the controller 120 determines whether or not the data packet is found, and if YES, in step 807, the retransmission control algorithm device 105 removes the data packet from the retransmission data storage device 104, and The memory block occupied by the data packet is released for reuse and the process ends. On the other hand, if NO in step 806, the process ends.

Note that no assumptions have been made about how the data packets are determined. To one of ordinary skill in the art, the attributes used to identify a data packet can be any of the attributes of a data packet such as, but not limited to, the packet destination, time stamp, information embedded in the packet, and the like. It is clear that it can be one of, or any number of combinations. It is also possible to implement the search process using any algorithm. For example, a simple method is
Source data storage device 102 and retransmitted data storage device 1
All data packets in 04 are sent to the controller 120 (or the packet scheduling algorithm device 103 or the retransmission control algorithm device 1 one by one).
There is a comparison with the attribute set by (05).
However, it is not limited to this. It will be appreciated by one of ordinary skill in the art that other more sophisticated methods can be used to implement this.

When a request signal for discarding a predetermined data packet being accessed is received from the terminal device on the receiving side, the controller 120, the packet scheduling algorithm device 103 and the retransmission control algorithm device 105 controlled by the controller 120, A plurality of packets are identified using device-specified criteria, and these are identified using the packet removal mechanism of the network, such as, but not limited to, FIG.
02 and the retransmitted data store 104. It should be noted here that nothing is assumed about what request the terminal is making and what is the criterion for identifying the packet. A handy example that can be considered as a request from the terminal device is that when the receiving terminal device detects a lack of network resources, the receiving terminal device facilitates the timely transmission of an important part of the data stream. In order to do so, there is a requirement to not send unimportant parts of the data stream. Therefore, the receiving terminal device can request to send only the text portion of the content and omit the image. It will be clear to any person skilled in the art that other requirements are naturally supported.

For the transmission of specific data streams, there are specific dependencies between the data packets.
In this situation, the controller 120 and the packet scheduling algorithm device 10 controlled by it
3 and / or the retransmission control algorithm device 105,
Search the originating data store 102 and / or the retransmitting data store 104 to remove all data packets that depend on the packets removed as described above,
It is also possible to free up network resources to optimize performance.

When the transmission stop request signal is received from the receiving side terminal device, the controller 120 and the packet scheduling algorithm device 103 and the retransmission control algorithm device 105 controlled by the controller 120 are, for example, as shown in FIG. A packet to be transmitted to the terminal device is removed by using a packet removal mechanism which is not limited. As an example of a situation where such a request signal is generated,
There may be a pre-mature stop or transmission prohibition for accessing a given source from the receiving terminal. One skilled in the art will know that such a request signal can be generated in other situations as well.

Upon receiving the signal for closing the connection from the receiving side terminal device, the controller 120 and the packet scheduling algorithm device 103 and the retransmission control algorithm device 105 controlled by the controller 120 transmit the transmission data storage device 102 and the retransmission data storage device. At both 104, the data packets sent to the terminal are dropped. No assumptions are made about how the connection block is generated. For example, the signal is generated by the terminal device closing the connection when the terminal device ends the data access, or when the lower layer module device 131 detects a lost connection with the terminal device. It can be generated by the lower layer module device 131. However, it is not limited to these. It will be apparent to any person skilled in the art that there are other situations in which the request signal can be generated.

FIG. 9 shows an example of a possible method for updating the timeout attribute of a data packet in the transmission data storage device 102 or the retransmission data storage device 104. In step 901, when the controller 120 receives a request signal for updating the timeout attribute of a predetermined data packet from the receiving side terminal device,
In step 902, the packet scheduling algorithm device 1 for managing the transmission data storage device 102
03 to use a predetermined search mechanism to locate the specified data packet in the outgoing data store 102. Then, in step 903, the controller 120 determines whether the data packet is found,
If YES, in step 904, the packet scheduling algorithm device 103 is notified to the time-out attribute (for example, time-out value) of the data packet.
To change. After step 904 is completed, or if NO in step 903, in step 905, the controller 120 causes the retransmitted data storage device 1
04 to the retransmission control algorithm device 105 for managing
The specified data packet is transmitted to the transmission data storage device 102.
Allows the use of a predetermined search mechanism for positioning within.
Next, in step 906, the controller 120 determines whether or not a data packet has been found. If YES, in step 907, the retransmission control algorithm device 105 changes the timeout attribute of the data packet, and the process ends. To do. On the other hand, step 9
If NO in 06, the process ends. Here, nothing is assumed about how the data packet is positioned and what format the timeout attribute is. It will be appreciated by any one of ordinary skill in the art that the methods described above can be used to place data packets, and that other methods not mentioned are also available. The time-out attribute is, for example, an integer-valued time-out period embedded in the data packet header, and is represented by, for example, a relative time from when the packet loss is detected to when the data packet is removed. However, it is also clear that the above-mentioned timeout attribute is not limited to this and can be easily modified.

FIG. 10 shows one possible method for implementing the reuse of data packets in the retransmitted data storage device 104. If there are multiple requests to send the same packet, the method may be used to duplicate the data packet and retransmit it to the data store 10.
The time used to insert 4 is saved. In step 1001 of selecting a packet for transmission,
The controller 120 causes the packet scheduling algorithm device 103 to select and retrieve a data packet for transmission from the outgoing data storage device 102. The above step 1001 corresponds to step 301 of FIG.
And 302. In step 1002,
The controller 120 first transmits information related to the data packet to the retransmission control algorithm device 105 in order to compare the data packet with the data packet stored in the retransmission data storage device 104, and the retransmission control algorithm device 105 transmits the information. The retransmitted data store 104 is searched to determine if the data packet is already in it. If the data packet already exists in the retransmitted data storage device 104, step 1
In 003, the data packet is transmitted to the lower layer module device 131 for transmission, and in step 1004,
The controller 120 only notifies the corresponding information to the retransmission control algorithm device 105 that manages the retransmission data storage device 104, the retransmission control algorithm device 105 performs the corresponding operation to update the record, Then, in step 1005, the timeout attribute of the data packet is updated. Also, step 10
No in 02, that is, if the data packet does not already exist in the retransmitted data storage device 104, in step 1006, the controller 12
0 is the packet scheduling algorithm device 103
Let this duplicate the data packet. After this, in step 1007, the packet scheduling algorithm device 103 sends the data packet to the lower layer module device 131 for transmission. These two steps are similar to steps 303 and 304 of FIG. The data packet is retransmitted data storage device 10
4 is not present, the controller 120 proceeds to step 1008, similar to steps 305 and 306 of FIG.
In step 1009, the retransmission control algorithm device 105 inserts the data packet into the retransmission data storage device 104, and in step 1009, the packet scheduling algorithm device 103 attaches a timeout attribute to the data packet. Step 1005 or Step 10
After the timeout attribute of the data packet is changed in 09, it is determined in step 1010 that all the requests corresponding to the data packet have been executed, or in step 1011 that the changed timeout period has been exceeded. If yes, step 1
At 012, the data packet in retransmitted data store 104 is dropped. When a data packet is sent to the outgoing data store 102 for retransmission,
Instead of the data packet being removed from the retransmitted data store 104, the data packet is processed until all requests for that data packet have been processed and the updated timeout value is greater than the others (step 10).
When both 10 and 1011 are NO), they are continuously held in the retransmitted data storage device 104.

FIG. 11 shows one of the modifications that can be implemented in an arbitrary network element (NE) and can perform controlled caching using a content-specific transmission control and a content caching control mechanism. It is a block diagram of the illustrated system configuration. A network node 1101, which is an example of a relay device, is a basic implementation for controlling caching in network components. A network element is any interconnected element in a packet switched network that is capable of performing packet routing, storage and other important functions required by a packet network to carry data services, here Then, it refers to the source network component 1110, the intermediate network component 1111, the network node 1101, and the receiving side terminal device 1112.

The data stream is controlled by the network node 11 via the input interface 1102 of the stream of content, which is capable of controlled caching.
01, and is output from the network node 1101 which is a caching control mechanism via the output interface 1107 of the content stream. Input to the data block 1101 of the network node,
The output data stream is monitored by the content caching control mechanism 1106. Only data packets from a stream that need to be transmitted to downstream network components or from a stream that does not need to be controlled by a content-specific transmission control mechanism are typically 1202 in FIG. Stored in a short-term buffer memory such as. The input interface 1102 sends the input data stream (s) to the content caching control mechanism 110.
6 and the input session transmission controller 1103, respectively. Input session transmission controller 11
03 measures and controls the data stream input to the buffer memory 1104 under the control of the content caching control mechanism 1106, and the output session transmission controller 1105 also under the control of the content caching control mechanism 1106 outputs from the buffer memory 1104. Measuring and controlling the data stream being processed. Here, the input and output session transmission controllers 1103 and 1105 are provided to process a data stream input to or transmitted to a cache memory enabled network element. Also, the buffer memory 1104 is monitored and / or controlled by the content caching control mechanism 1106 for its internal state. Based on the traffic conditions measured by the content caching control mechanism 1106, the processed decisions for controlling timing are input session transmission controller 11
03, the output session transmission controller 1105,
Or sent to both the input and output session transmit controllers. The data is cached or stored in the buffer memory 1104. Finally,
Output interface 110 for content stream
7 superimposes the data packet output from the output session transmission controller 1105 and the data packet output from the content caching control mechanism 1106, and transmits it to the receiving side terminal device 1112.

These input and output session transmission controllers 1103 and 1105 are examples of content-specific transmission controllers generated specifically for one or more data streams. Then, the content caching control mechanism 1106 causes the network node 1
Data retrieved from the input session transmit controller 1103 and stored in the buffer memory 1104 for a particular data stream based on traffic conditions measured by monitoring the data stream to each component within 101. Determine the amount of streams. The data rate sent and received from the buffer memory 1104 is based on the timing information sent to each session transmit controller entity. The same timing information was also sent to each session transmit controller entity to control the input and output rates. In some implementations, there is only one (input or output) session transmit controller entity, depending on what functionality the caching is being performed on. For example, the source network component 1109
May require only the illustrated output session transmit controller entity, and other intermediate network components 1111 may have both input and output session transmit controllers.

FIG. 12 is a block diagram of a detailed configuration of the content caching control mechanism 1106 of FIG. 11 using a content-specific transmission controller to enable caching in multiple network components. Content caching control mechanism 110
6 is also used to determine the timing of control, and session transmission controllers 1103 and 11
05 and buffer memory 1104, respectively, to generate the appropriate signals. The buffer memory 1104 referred to here is a hard disk, a semiconductor memory, or another device capable of storing data at a speed required by the transmission speed of the I / O of the network component with the cache memory enabled. Is possible.

Traffic Detector Function Block 120
1 refers to the input data stream and the output data stream, and based on the traffic bandwidth, the rate during the arrival of a particular data stream and the rate of retransmission, the traffic of the input and output ports of the network element. To monitor. Based on the monitored results,
Signals controlling the session rescheduler 1204, the input and output session transmission controllers 1103 and 1105 generated inside the network component, and the cache memory controller 1205 are sent to the caching regulator 1203. The caching regulator block 1203 determines the amount of memory to be cached based on the allocated memory size and the stream priority. It then controls the amount of storage and sets the appropriate commands and signals to transfer between the storage and the entities of the input and output session transmission controllers 1103 and 1105. If there is a particular low priority stream or a fully cached stream that requires a terminated transmission control entity to be reused, the caching regulator 1203 is responsible for later reception and transmission recovery. As possible, the session rescheduler 1204 can be sent such information to hold information on the data stream session. The session rescheduler 1204 also mitigates transient traffic congestion and allows traversal, transmission and reception of high priority data streams based on the state of the monitored traffic at input and output, It acts as a suspend and restore function for caching data streams in network components. Therefore, the caching regulator 1203 and the session rescheduler 1204 send a control signal to the cache memory controller 1205 to cause the cache memory controller 1205 to control the operation of the buffer memory 1104. The caching control mechanism 1106 can also store the data stream in a short-term buffer memory 1202 connected in parallel with the traffic detector 1201, as described above.

As described above, according to the relay device and the relay method for the packet switching communication network according to the embodiment of the present invention, the content transmission between the ends requires the movement through a plurality of network components. In a packet-switched data network that implements, selective retransmission of real-time content data and caching of content data are enabled. A certain quality of service can be guaranteed for the generated path, but a sudden surge of traffic conditions at a single node can degrade the transmission quality of service, which is expected at the termination point. The level of service provided is reduced. A relay device and a relay method of the present invention change the presentation timing of a content object in a data stream whose transmission is controlled,
It thereby solves the problem of content transmission services by reducing the transmission rate of a single content object, which may span multiple data packets. In accordance with the present invention, a content-specific, cache-memory-enabled repeater with selective retransmission technology is used to achieve high quality content transmission without denial of service to low priority streams. be able to. A relay device and a relay method according to the present invention are to enable a high-quality transmission service level for a data stream in which contents of all classes are specified in a service quality-conscious network.

In the embodiment according to the present invention, a relay device such as a gateway or a router is provided with a cache, and when a retransmission request is required, a server which is a data source (source) can directly retransmit the data. Instead, the retransmission is performed from the cache memory of the relay device to improve the use efficiency of the transmission band. The present invention provides this framework device with a new retransmission and acknowledgment mechanism. Regarding retransmission, if the network is extremely congested, send a control signal to suppress retransmission,
If the network is lightly congested, the retransmission request signal transmission rate should be half the original value.
The interval for requesting retransmission is controlled according to the congestion level of the network. That is, if congestion occurs, the interval for requesting retransmission is reduced. Similarly, the acknowledgment mechanism sends a control signal that suppresses the acknowledgment when the network is extremely congested, and the transmission rate of the acknowledgment signal when the network is lightly congested. Is transmitted to half of the original value, the interval of affirmative response is controlled according to the congestion degree of the network. With the above method, network resources (transmission bandwidth)
Make effective use of.

[0081]

As described above in detail, according to the relay device for the packet switching communication network of the present invention,
A relay device, which is used in a packet-switched communication network, for controlling a content-specific transmission to a terminal device that receives a data packet, the terminal device detecting a data packet reception error, and Means for automatically transmitting a signal requesting retransmission of a data packet, and means for voluntarily transmitting a signal requesting retransmission of the data packet when reception of the data packet fails within a predetermined timeout period And the relay device comprises retransmission request control means, and the retransmission request control means prohibits the terminal device receiving the data packet from generating a signal requesting retransmission of the data packet. Control means and a signal requesting retransmission of the data packet by the terminal device receiving the data packet. And means for controlling so as to limit the raw to rate.

Further, in the relay device, the retransmission request control means sends the data packet to the terminal device receiving the data packet when the congestion level of the network is equal to or more than a predetermined first threshold value. A control signal that prohibits requesting retransmission is transmitted, and the degree of network congestion is smaller than the first threshold and the first
Is greater than or equal to a second threshold value smaller than the threshold value, the control signal for reducing the transmission rate of the signal requesting retransmission of the data packet is transmitted to the terminal device receiving the data packet. When the network congestion level is smaller than the second threshold value, by transmitting a control signal permitting requesting retransmission of the data packet to a terminal device receiving the data packet, Coordinating traffic associated with retransmission of multiple data packets in multiple data streams in the packet switched communication network.

Further, the relay device further comprises an acknowledgment control means for controlling the operation of the terminal device receiving the data packet transmitted from the relay device, transmitting an acknowledgment signal for the data packet,
The acknowledgment control means transmits a control signal for prohibiting the transmission of the acknowledgment signal to the terminal device receiving the data packet when the congestion level of the network is equal to or higher than a predetermined first threshold value. , The degree of network congestion
When it is smaller than the first threshold and equal to or larger than a second threshold smaller than the first threshold, a transmission rate of an acknowledgment signal to the terminal device receiving the data packet. And a control signal for permitting the terminal device receiving the data packet to transmit an acknowledgment signal when the network congestion level is smaller than the second threshold value. Transmitting regulates traffic associated with transmitting and / or retransmitting multiple data packets in multiple data streams in the packet switched communication network.

Further, in the relay device, a transmission data storage device for storing a plurality of data packets transmitted to the terminal device receiving the data packet, and a plurality of transmission data storage devices transmitted to the terminal device receiving the data packet. A retransmission data storage device for storing a copy of the data packet, and a first device from the terminal device for receiving the data packet.
Means for changing the timeout attribute of the data packet stored in the transmission data storage device in response to the request signal from the terminal device, and the second replay signal in response to the second request signal from the terminal device receiving the data packet. Transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switching communication network, further comprising means for changing a timeout attribute of a duplicate of a data packet stored in a transmission data storage device. Traffic related to.

Therefore, according to the present invention, network congestion can be prevented and network resources can be effectively used when controlling transmission of real-time contents in a packet-switched communication network.

According to the invention, the control of the transmission of retransmission request signals and the transmission of acknowledgment signals, and the utilization of retransmission request signals and acknowledgment signals reception, consists of more than one data packet. It can aid in the scheduling of data content objects. Further, the present invention is used when distributing and transmitting real-time content on a network in which fluctuations (jitter) related to the arrival of a data packet between end points are large.

The present invention uses retransmission and / or acknowledgment mechanisms to enable efficient use of network resources. The present invention implements processes related to how retransmission and / or acknowledgment mechanisms can be controlled in association with flow control mechanisms to achieve optimal utilization of valuable network resources, resulting in retransmission requests. It is possible to prevent network congestion due to the transmission of signals and / or acknowledgment signals. A new, selective re-transmission and acknowledgment mechanism is used to achieve new levels of transport service for all prioritized classes of data streams in quality of service networks. In addition, the present invention can be shared with a content caching mechanism. With the present invention, extended network components (gateways, routers, switches, intelligent hubs and other network components), widely used in building public or corporate wide area networks, serve low priority traffic. The problem of rejection can be solved. The invention also makes it possible to provide network operators with a wide range of network services in packet-switched communication networks, which meet different requirements in the transmission of real-time content, near real-time content and non-real-time content.

The present invention provides traffic conditions through the use of caching, retransmission, and acknowledgment mechanisms provided at each network element along the path from the streaming server to the desired recipient. The control is used. Usually, the data stream is first generated by the streaming server upon receiving a request signal from the end user. The present invention does not specify a mechanism for generating a data stream, nor imposes any restrictions on such a mechanism. However, this requires notification of the creation of the data stream so that the proper network / memory resources can be allocated.

A plurality of Content Objects are inserted in the data stream. These are inserted into the storage device to determine the schedule. Upon transmission, a copy of the data content is stored to facilitate retransmission. A time-out period is associated with such a copy and is purged from memory when the time-out period expires or when an acknowledgment signal is received. When setting the timeout period, the present invention considers the value of the presentation time of the content object, if applicable. In addition, if there is a dependency between content objects, the retransmission request signal from the receiving terminal is monitored so that the scheduling of the content objects can optimize the dependency.

The network congestion state is monitored so that the device according to the invention can efficiently control the rate of retransmission request signals and / or acknowledgment signals that can be transmitted by the receiving terminal device. On top of that, so that Content Objects can be efficiently transmitted to different end users,
The present invention provides a caching mechanism.

The present invention can be used in multiple network components along a route from a streaming server to a desired end user. The invention also provides a mechanism for removing content objects that are still present in the network component when the data stream is closed.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a part of a network including relay devices 1-1 to 1-N according to an embodiment of the present invention.

FIG. 2 is a flowchart showing a data packet receiving process executed when the upper layer module device 130 of FIG. 1 transmits a new data packet to the lower layer module device 131 for transmission.

FIG. 3 is a flowchart showing a content object transmission process executed when the packet scheduling algorithm device 103 of FIG. 1 selects a content object from the transmission data storage device 102 for transmission to the network.

FIG. 4 is a flowchart showing a response process to a retransmission request signal, which is executed by the controller 120 of FIG.

FIG. 5 is a flowchart showing a response process performed by the controller 120 of FIG. 1 in response to a retransmission request signal in consideration of data packet dependency.

FIG. 6 is a flowchart showing a transmission rate control process of a retransmission request signal, which is a decision step of the controller 120 of FIG. 1 executed in consideration of the current congestion state of the network.

7 is a flowchart showing a control process of a transmission rate of an acknowledgment signal transmission, which is a decision making step of the controller 120 of FIG. 1 executed in consideration of the current congestion state of the network.

8 is a flowchart showing a data packet removal process executed when selecting and removing a data packet having a specific attribute from the transmission data storage device 102 and / or the retransmission data storage device 104 of FIG.

9 is a flowchart showing a data packet timeout attribute changing process executed when the controller 120 of FIG. 1 selects a data packet having a specific attribute and changes the attached timeout attribute.

FIG. 10 shows a data packet reuse process performed when the controller 120 of FIG. 1 reuses a data packet in the retransmitted data storage device 104 when there are multiple requests for the same data packet. It is a flowchart shown.

FIG. 11 is a system configuration diagram of a network path configured by using a cache memory enabled network component and a function showing a configuration of the cache memory enabled network component according to a modified example of the present invention. It is a block diagram.

12 is a block diagram showing a detailed configuration of a content caching control mechanism 1106 used as a main caching engine in the cache memory enabled network component of FIG. 11. FIG.

[Explanation of symbols]

1-1 to 1-N ... Relay device, 101 ... Receiving side interface, 102 ... Outgoing data storage device, 103 ... Packet scheduling algorithm device, 104 ... Retransmission data storage device, 105 ... Retransmission control algorithm device, 106 ... Transmission Side interface, 107, 108, 109, 110, 111, 112 ... Data path, 113, 114, 115, 116, 117, 118 ... Control signal path, 120 ... Controller, 130 ... Upper layer module device, 131 ... Lower layer Module device of 1101, ... Network node, 1102 ... Input interface of content stream, 1103 ... Input session transmission controller, 1104 ... Buffer memory, 1105 ... Output session transmission controller, 1106 ... Context Cache caching control mechanism, 1107 ... Content stream output interface, 1110, 1111 ... Network component, 1112 ... Receiving side terminal device, 1201 ... Traffic detector, 1202 ... Short-term buffer memory, 1203 ... Caching regulator, 1204 ... Session rescheduler , 1205 ... Cache memory controller.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Chen Hong             Singapore 534415 Singapore, Thailand             Sen Avenue, Block 1022, 04-             No. 3530, Thai Sen Industrial             Estate, Panasonic Singapore             Research Institute Co., Ltd. (72) Inventor Baek Tan             Singapore 534415 Singapore, Thailand             Sen Avenue, Block 1022, 04-             No. 3530, Thai Sen Industrial             Estate, Panasonic Singapore             Research Institute Co., Ltd. F-term (reference) 5K030 GA13 HA08 HB21 LA01 LB05                       LE17 MB09 MB16                 5K034 AA07 AA09 DD03 EE11 FF11                       HH01 HH02 MM03

Claims (8)

[Claims] 1. A relay device used in a packet switching communication network for controlling content-specific transmission to a terminal device receiving a data packet, wherein the terminal device receives a data packet reception error. Means for automatically transmitting a signal requesting retransmission of the data packet, and spontaneously issuing a signal requesting retransmission of the data packet when reception of the data packet fails within a predetermined timeout period. And a retransmission request control means, and the retransmission request control means generates a signal for a terminal device receiving a data packet to request retransmission of the data packet. And a terminal device that receives the data packet retransmits the data packet. And a means for controlling so as to limit a rate of generating a signal requesting a packet. A relay device for a packet-switched communication network. 2. The retransmission request control means requests the terminal device receiving the data packet to retransmit the data packet when the congestion level of the network is equal to or higher than a predetermined first threshold value. And a network congestion degree is equal to or greater than a second threshold value that is smaller than the first threshold value and smaller than the first threshold value. When a control signal for reducing the transmission rate of the signal requesting retransmission of the data packet is transmitted to the terminal device receiving the data packet, and the degree of network congestion is smaller than the second threshold value, By transmitting a control signal permitting a request for retransmission of the data packet to a terminal device that receives the data packet, the packet switching communication network is transmitted. The relay device for a packet-switched communication network according to claim 1, wherein the relay device adjusts traffic related to retransmission of a plurality of data packets in a plurality of data streams. 3. The relay device further comprises acknowledgment control means for controlling an operation of a terminal device receiving a data packet transmitted from the relay device, transmitting an acknowledgment signal for the data packet, The acknowledgment control means transmits a control signal for prohibiting the transmission of the acknowledgment signal to the terminal device which receives the data packet, when the congestion degree of the network is equal to or higher than a predetermined first threshold value, When the network congestion level is smaller than the first threshold value and is equal to or larger than a second threshold value smaller than the first threshold value, the terminal device receiving the data packet is notified. Send a control signal to reduce the transmission rate of the acknowledgment signal, and receive the data packet when the network congestion level is less than the second threshold value. Traffic for transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switched communication network by transmitting a control signal that permits the terminal device to transmit an acknowledgment signal. The relay device for a packet-switched communication network according to claim 1, wherein 4. An outgoing data storage device storing a plurality of data packets transmitted to a terminal device receiving the data packet, and a copy of the plurality of data packets transmitted to the terminal device receiving the data packet. And a means for changing the timeout attribute of the data packet stored in the transmission data storage device in response to a first request signal from the terminal device that receives the data packet. The packet switching means further comprising: means for changing a timeout attribute for copying the data packet stored in the retransmitted data storage device in response to a second request signal from a terminal device that receives the packet. Transmission and / or retransmission of multiple data packets in multiple data streams in a communication network The relay device for a packet-switched communication network according to claim 1, wherein the relay device regulates traffic related to the communication. 5. A relay method used in a packet-switched communication network for controlling content-specific transmission to a terminal device receiving a data packet, wherein the terminal device receives a data packet reception error. Automatically sending a signal requesting retransmission of the data packet, and when the reception of the data packet fails within a predetermined timeout period, a signal requesting retransmission of the data packet is voluntarily issued. Transmitting the data packet, the relay device controls the terminal device receiving the data packet to prohibit generation of a signal requesting retransmission of the data packet, and the relay device receiving the data packet. Limits the rate at which the terminal device generates a signal requesting retransmission of the data packet. Relaying method for a packet-switching communication network, comprising: 6. A control signal for prohibiting requesting retransmission of the data packet to a terminal device receiving the data packet when the network congestion level is equal to or higher than a predetermined first threshold value. And a terminal for receiving the data packet when the congestion level of the network is equal to or greater than a second threshold value that is smaller than the first threshold value and smaller than the first threshold value. Transmitting a control signal for reducing a transmission rate of a signal requesting retransmission of the data packet to the device; receiving the data packet when the congestion degree of the network is smaller than the second threshold value Transmitting a control signal that permits the terminal device to request retransmission of the data packet. Relay method for according to claim 5, wherein the packet-switched communication network, characterized in that in a switched communications network to adjust the traffic of the re-transmission of a plurality of data packets in the plurality of data streams. 7. The relay method further comprises controlling a terminal device receiving a data packet transmitted according to the relay method to transmit an acknowledgment signal for the data packet, the step comprising: When the congestion level is equal to or higher than a predetermined first threshold value, a step of transmitting a control signal for prohibiting the transmission of an acknowledgment signal to the terminal device receiving the data packet, and the network congestion level, When it is smaller than the first threshold and equal to or larger than a second threshold smaller than the first threshold, a transmission rate of an acknowledgment signal to the terminal device receiving the data packet. Transmitting a control signal to reduce the data packet when the network congestion level is less than the second threshold value. The step of transmitting a control signal that permits the receiving terminal device to transmit an acknowledgment signal, thereby transmitting and / or retransmitting a plurality of data packets in a plurality of data streams in the packet switched communication network. 7. The traffic according to transmission is adjusted, according to claim 5 or 6.
A relay method for a packet-switched communication network as described. 8. A step of storing, in an outgoing data storage device, a plurality of data packets transmitted to a terminal device receiving the data packet, and a duplication of the plurality of data packets transmitted to the terminal device receiving the data packet. In the retransmitted data storage device, and in response to a first request signal from the terminal device receiving the data packet, changing the timeout attribute of the data packet stored in the transmission data storage device. And changing the timeout attribute of the duplication of the data packet stored in the retransmitted data storage device in response to a second request signal from the terminal device receiving the data packet, In the packet-switched communication network described above, multiple data streams in multiple data streams are 6. A relay method for a packet-switched communication network according to claim 5, characterized in that traffic related to packet transmission and / or retransmission is adjusted.