KR20060009775A - Multimedia packet transmission device and method - Google Patents

Abstract

In accordance with an aspect of the present invention, an apparatus for transmitting a multimedia packet includes a storage unit for storing a QoS class, a policy, and classification result information according to the class or policy, and the classification result information stored in the storage unit. The priority information of the multimedia packet data of the layer 3 or more packet of the packet is examined, and each multimedia data packet is classified according to the class of service classified by the DPI priority classifier and the DPI priority classifier for granting an appropriate service class for each packet. And a display unit for displaying the service level.

Description

Apparatus and Method for Transmitting Multimedia Packet

1 is a general QoS building block diagram.

2 is a structural diagram of a field used for a general deep packet inspection (DPI).

3 is an RTP payload classification structure diagram.

4 is a structural diagram of a general MPEG frame type.

5 is a block diagram of a priority based QoS structure for a multimedia packet in accordance with the present invention.

6 is a diagram illustrating a structure of a DPI target field of a multimedia packet considering priority according to the present invention.

Figure 7 is a preferred embodiment of a multimedia packet classification method according to the present invention.

* Description of the symbols for the main parts of the drawings *

101: Classifier 102: Storage unit (QoS table)

103: Marker

104: Congestion Avoidance

105: measuring unit 106: waste disposal unit (Dropper)

107, 108, 109: Queue 303, 600: RTP header

401: I-frame 402: P-frame

403: B-frame 501: DPI priority classifier

601: Priority field

The present invention relates to a packet search and classification method for guaranteeing a differentiated quality of service of a multimedia packet. More specifically, the present invention relates to a multimedia service in the case of classifying QoS grade by inspecting a multimedia packet providing a video or audio service. It searches for fields and objects that indicate internal priorities and classifies and processes QoS classes so that high-priority packets receive high-level services within one multimedia service. The present invention relates to an apparatus for transmitting multimedia packets and an method thereof.

1 illustrates a typical QoS building block.

The structure block for processing QoS generally includes a structure block for supporting DiffServ (Differentiated Services) in the transmission equipment, and a storage unit (QoS table) containing information such as QoS class or policy. 102 and Classifier 101, which searches and classifies packets in consideration of their priorities, are the most important part.

When various signals such as audio signals, video signals, data, etc. are introduced from the outside, the classifier 101 analyzes the contents of the packet headers according to a rule defined at the time of packet reception to determine which flow / class the packet belongs to. The data is transmitted to the measuring unit 105.

The measurer 105 measures a temporary property of the traffic stream, determines whether the packet satisfies the profile, and transmits the information to the display 103 and the dropper 106.

The marker 103 displays some fields of the classified packets to specify the packet type. Specifying the packet type allows for selective processing of the packet later. The display unit 103 transmits the data specifying the packet type to the stack removal unit 104.

The dropper 106 acts as a special shaper that discards all packets that do not satisfy the profile, where the shaper is a packet with a buffer of a certain size that does not satisfy the profile. A device that delays all or some packets in a packet stream until

The decompression unit 104 receiving data from the display unit 103 prevents congestion that may cause packet loss, determines the priority as indicated in the signal, and transmits the data to the queue corresponding to each packet.

In the example of FIG. 1, cue 1 107 transmits the audio signal judged to have the highest importance, cue 2 108 transmits the next important video signal, and cue N 109 transmits the general data having the less importance. Doing.

In order to guarantee the quality of service (QoS) in a packet-based transmission equipment, a packet has a QoS building block. In this case, the packet classifier 101 inspects each packet to determine what class of service the packet has. The service class is reviewed and classified into a class of service suitable for each packet. Each packet can be classified by five policies. The five policies include five tuples, an IP protocol (Internet Protocol Procedure), a transmission digital broadcast field, DSCP (DiffServ Code Point), EXP (MPLS), and COS (VLAN).

The 5-tuple based method for retrieving packets in units of each flow is generally used in edge transmission equipment in the DiffServ (Differentiated Services) network area, and the IP procedure or DSCP It is used to retrieve the service class of already classified packets.

In this case, DiffServ is a protocol for assigning and controlling network traffic by class so as to have priority over other types of general traffic for relatively special types of traffic such that voice should not be interrupted. DiffServ is the most advanced way of managing traffic in the form of a class of service, or Class of Service (CoS).

Unlike earlier approaches such as tag usage in 802.1p and Type of Service (TOS), DiffServ uses more complex policy or rule statements instead of simply tagging priorities to determine how to deliver a given network packet. Use In a given packet movement rule, a packet is subjected to per-hop movement, that is, one of 64 possible forward movements called Per Hop Behaviors (PHB). A six-bit long field called DiffServ Code Point (DSCP) in the IP header specifies the per-hop movement for a given packet flow.

In addition, the MPLS (Multi Protocol Label Switching) network can be searched based on the EXP (experimental 3bit) field of the MPLS header, and in the VLAN (Virtual LAN) network, the service grade is determined by using the COS field of Ethernet. Classify

All such packet classification information is performed based on the information stored in the QoS table. In addition to the above-described information, the QoS table 102 may store various additional information at the application level.

In particular, a method of classifying a multimedia packet using a user datagram protocol (UDP) port of a realtime transfer protocol (RTP) used for a multimedia service for retrieving the multimedia service packet is also used. In general, the RTP protocol uses an even number of UDP ports defined by the application.

In recent years, network-based application recognition, such as protocol detection and deep packet inspection (DPI) technology, which classifies packets based on protocols and applications of layers 4 to 7, has been actively performed. It is under development.

2 illustrates a structure of a field used for general deep packet inspection (DPI).

As a method for recognizing a packet of an application program, there is a 5-tuple classification method. The 5-tuple includes the L3 protocol ID 202, the source IP address (SOURCE IP ADDR) 203, the destination IP address (DST IP ADDR) 204, the source port (SRC PORT) 205, and the destination port (DST PORT). 206.

In addition to the 6-tuple information including the DSCP (or TOS 201) information of FIG. 2, the packet detected by the transmission device is detected by searching for a sub port or deep inspection pattern 207 of the actual packet. In some cases, a method of identifying a packet belonging to an application program and assigning an appropriate grade of service to the application program may be used.

Assuming that voice, video, and data packets enter the transmission equipment at the same time, the transmission equipment typically processes latency-sensitive voice packets in the highest priority queue for service differentiation, and then In this case, the service class is set such that video packets are processed in a queue having the next highest priority, and general data packets are processed in a queue having the lowest priority.

FIG. 3 illustrates a method of classifying service grades that is slightly different from that of FIG. 2.

3 shows an RTP payload classification structure.

As shown in FIG. 3, in order to dynamically classify a multimedia service, a DPI method of classifying up to an RTP payload of a packet may be used. In addition to the IP header and the UDP header 302, it searches up to the PT (Payload Type) 305 in the RTP header 301 which specifies the format of the data being transmitted by the RTP packet. It is to find out the codec information. Based on this, it is possible to classify service grades of multi-coded multimedia applications to be changed dynamically.

Since these technologies generally classify the service according to the general characteristics of the service such as voice, real-time video, non-real-time video, and general data, even if the method shown in FIGS. 2 and 3, which is the latest technology using DPI, is applied. The minimum criteria for determining the service level can only be limited to the application level.

However, in recent years, there is a need to classify the service class with various policies in the transmission equipment with various applications and corresponding characteristics. In terms of users, the service grade policy has a more significant meaning. In particular, in the case of multimedia traffic, data inside an application program has a priority, and the most representative example is a moving picture expert group (MPEG).

4 illustrates the form of a general MPEG frame.

In general, an MPEG image object may be divided into an I-frame 401, a P-frame 402, a B-frame 403, and the like, and the I-frame 401 includes all the information of a still image. The frame 402 or the B-frame 403 contains information on the difference from the previous image. Accordingly, it can be said that the I-frame 401 has higher priority in terms of the importance of information experienced by the user than the B-frame 403 or the P-frame 402 among the data information of MPEG. Recently, the MPEG service system based on the data priority recognition between the MPEG server and the client is also being studied.

However, multimedia data with this priority, which affects the MOS (Mean Opinion Score), which is generally a service class that users actually feel, is one application having the same service class even if the network uses DPI technology provided up to now. It has a limitation that can only be recognized as a program.

In order to solve the above problems, the present invention automatically detects data traffic having a priority in terms of a service user in the same service in a transmission device, and assigns a suitable service level to the multimedia application program in the same network situation. An object of the present invention is to provide a multimedia packet transmission device and a method for improving a service level that can be experienced by a user.

In accordance with an aspect of the present invention, an apparatus for transmitting a multimedia packet includes: a storage unit for storing a quality of service (QoS) class, a policy, and classifying result information according to the class or policy, for the packet data class retrieval; Through the DPI priority classifier and the DPI priority classifier for checking the priority information of the layer 3 or more multimedia packet data of the packet by using the classification result information stored in the packet, and assigning an appropriate service level to each packet. And a display unit for indicating a service class in each multimedia data packet according to the classified service class.

The apparatus for transmitting a multimedia packet may include a measuring unit which measures a property of a packet received from the DPI priority classifier and determines whether the packet satisfies a profile, and discards packets that do not satisfy the traffic profile as a result of the measuring unit. The processor, a block removal unit for preventing congestion that may cause packet loss, and sorting by class indicated in the packet data, and packet data for each service class sorted by the class are sequentially stored and transmitted to an external network. It may further include one or more queues.

The DPI priority classifier classifies the priority of packet data by searching not only the PT (Payload Type) of the RTP header but also a priority field (Priority Data) inside the PT of the actual multimedia packet.

According to another aspect of the present invention, there is provided a method for transmitting a multimedia packet, comprising: a storing step of storing a QoS class, a policy, and classification result information according to the class or policy, and a packet using the stored classification classification result information DPI priority classification step of checking the priority information of the multimedia packet data of the layer 3 or more of the above, and assigning a suitable service level for each packet, and a display step of displaying the service level in each multimedia data packet according to the classified service class It includes.

According to the multimedia packet transmission method according to the present invention, the DPI priority classification in the case of the introduction of Voice over Internet Protocol (VoIP) and MPEG data packets, the priority of the voice signal to the MPEG header or GOP header Secondary priority, third order priority to MPEG I-frame, and lowest order priority to MPEG P-frame or B-frame.

Hereinafter, a preferred embodiment according to the present invention will be described in detail with reference to the drawings.

The present invention can be largely divided into the entire QoS block for processing QoS and the packet searching up to the priority information level of the multimedia packet.

5 illustrates a priority based QoS structure block for a multimedia packet according to the present invention.

The structure block for processing QoS generally includes a structure block for supporting DiffServ in a transmission equipment, and actually has priority with a storage unit (QoS table) 102 containing information such as QoS class or policy. The DPI priority classifier 501 that searches / classifies a packet in consideration of the ranking is the most essential part.

The display unit 103 displays each service class with the QoS policies classified by the DPI priority classifier 501, and measures other than the other components such as the measurement unit 105, the disposal unit 106, and the accumulation elimination unit ( 104 and queues 507, 508, 509 and the like play the same role as in the conventional DiffServ QoS structure block described with reference to FIG. 1.

The DPI Prioritized Classifier 501 expands the function of the existing classifier and searches not only the L3 information of the packet but also information from L4 to L7, so that the UDP port of the multimedia traffic, the type of codec and the priority information inside the service. It may have a function of searching and the like, and may have hardware memory space for this in order to increase the efficiency of the search speed.

Referring to the operation of each block constituting the multimedia packet transmission apparatus according to an aspect of the present invention.

If the priority is defined as P ₀ , P ₁ ,... P _N in the multimedia service that can have internal priority, the packets constituting Service 1, Service 2, and Service 3 are as follows. It can be defined together.

MM service 1 = SUM (S1P0, S1P1, ......, S1PN)

MM service 2 = SUM (S2P0, S2P1, ......, S2PN)

MM service 3 = SUM (S3P0, S3P1, ......, S3PN)

The DPI priority classifier 501 which supports multimedia priority search performs DPI for QoS class setting in consideration of these priorities, and classifies the service class according to each policy based on the information of the packets retrieved in consideration of the priority. Is set on the display unit 103. The policy and classification results for this search are all stored in the QoS table 102, which may be set by the transmitting equipment operator or by an automated method.

Through this procedure, multimedia packets having differentiated service grades are transmitted to a queue set for the corresponding grade of service to be processed according to each grade of service, which is the last part of the transmission equipment.

As shown in FIG. 5, packets are processed in queues 1, 2, and N according to their priorities, and packets processed in each queue are shown in the following format.

P0 = SUM (S1P0, S2P0, S3P0)

P1 = SUM (S1P1, S2P1, S3P1)

PN = SUM (S1PN, S2PN, S3PN)

Here, P0 represents the highest priority, and the packet indicated by P0 is transmitted to queue 1 507 of FIG. P1 is Medium Priority, and the packet indicated by P1 is transmitted to Queue 2 508 which processes the medium priority packet. The PN represents the lowest priority and is transmitted to and processed by the least important queue N 509.

6 illustrates a structure of a DPI target field of a multimedia packet in consideration of priority according to the present invention.

The DPI algorithm (Prioritized DPI Algorithm) of the present invention uses the DPI priority classifier 501 to classify a packet by searching the fields as shown in FIG. 6 including a field for searching for an existing multimedia packet.

Referring to FIG. 6, the TOS 201, the L3 protocol ID 202, the source IP address 203, the destination IP address 204, the source port 205, the destination port 206, and RTP, which are also shown in FIG. 2. Header 600 and priority data 601.

In addition to the fields shown in FIG. 2, it can be seen that the RTP header 600 and the priority field 601 are additionally included. What role these packet fields play will be described together with reference to FIG. 7.

Figure 7 shows a preferred embodiment of a multimedia packet classification method according to the present invention.

As shown in Fig. 7, service is provided for a Voice over Internet Protocol (VoIP) packet 705, which is a multimedia packet which is not prioritized inside a transmission equipment, and an MPEG packet 706, which is a multimedia packet having internal priority. In determining the class, the previous DPI method uses RTP for both real-time video and audio packets, so it is determined to be the same multimedia service class. If the most recent technique is a DPI up to PT (Payload Type) 305 of the RTP header 600, it may be determined whether the corresponding service is a video service or a voice service through the information of the PT 305.

The classification method used in FIG. 7 goes one step further by using the DPI priority classifier 501 to prioritize not only the PT 305 of the RTP header 600 but also the payload of the actual multimedia packet. The field 601 is searched to differentiate priorities of services that can be experienced by the user for one multimedia application service.

As shown in FIG. 4, in the case of MPEG, priority is given to each object, header, frame, etc. In general, in the case of MPEG, the service class according to the priority may be defined as follows. Can be.

First, class 1 MPEG and GOP headers are assigned with priority 0 or 1 EF or AF. For class 2 MPEG I-frame 401, priority 0 or 1 AF and class 3 MPEG are assigned. In the case of the B-frame 403 or the P-frame 402, priority 7 is assigned.

Herein, the PHB (Per Hop Behavior) of the differential service will be briefly described to help the understanding of the present invention.

In the differential service, a PHB can be roughly divided into a default PHB, an Explicit Forwarding (EF) PHB, and an Assured Forwarding (AF) PHB.

The default PHB refers to the same level of service as the best effort currently used on the Internet, and is applied to all packets that do not require a specific QoS service.

The EF PHB is the highest level of service in DiffServ and is suitable for service levels that require low loss, low latency, low jitter, and guaranteed bandwidth, such as VoIP and video conferencing.

AF PHB is a PHB for traffic based on Transmission Control Protocol (TCP). It is divided into four classes, and each class is serviced in its own physically divided queue to enable independent bandwidth management. In addition, three classes of revocation priority are applied within each class to further classify into 12 classes.

Therefore, as shown in FIG. 7, when a voice and a video packet enter a single transmission device, a delay-sensitive voice signal generally has the highest priority (EF Service), and then MPEG, which is the most important information of the video signal, is used. A header or a GOP (Group of Picture) header has a next priority AF4X, and an I-frame, which is the basis of the still picture signal of MPEG, is assigned the next priority AF3X. MPEG P-frame and B-frame packets indicating only differences from still picture signals can be set to have BE which is the lowest priority.

Such a setting is an embodiment, and the service class may be set differently according to the purpose, intention, or viewpoint of the person who manages the transmission network.

When the priority-based packet classification method described in the present invention is used, the transmission equipment can provide differentiated quality of service to packet information actually felt by a user in one multimedia service, so that network resources are bursty. In case of instantaneous degradation due to external causes such as bursty traffic, the quality of service felt by the user can be significantly reduced compared to the amount of packets lost in the actual network.

The present invention selects a mechanism for providing differentiated services according to the priority of packets provided in one multimedia service, and provides a differentiated service for high priority packets when network resources are limited. It has the effect of improving the level of QoS that is felt, and provides a higher level of DPI method by adopting the method of searching for packets related to internal priority when searching for packets, and it provides not only video service but also voice service and multimedia service. It has the advantage that it can be extended to all kinds of services that can have priority within one application service.

Claims (10)

In the packet transmission apparatus for providing a differentiated service level, A storage unit for storing a QoS class, a policy for classifying packet data classes, and classifying result information according to the class or policy; A Deep Packet Inspection (DPI) priority classifier for inspecting priority information of the layer 3 or more multimedia packet data of the packet by using the classification result information stored in the storage, and assigning an appropriate service level to each packet; And And a display unit for displaying a service class in each multimedia data packet according to the service class classified through the DPI priority classifier. The method of claim 1, A measurement unit which measures a property of a packet received from the DPI priority classifier and determines whether the packet satisfies a profile; A discarding unit for discarding packets that do not satisfy the traffic profile as a result of the measurement of the measuring unit; A block removal unit for preventing congestion that may cause packet loss and sorting by class indicated on the packet data; And And at least one queue for sequentially storing packet data of each service class arranged by each class and transmitting the packet data to an external network. The method of claim 1, The DPI priority classifier, A multimedia packet transmission apparatus for classifying packet data priorities by searching not only a payload type (PT) of a Realtime Transfer Protocol (RTP) header but also a priority field inside a PT of a multimedia packet. The method of claim 1, When the Voice over Internet Protocol (VoIP) and MPEG data packets are introduced into the transmission device, the DPI priority classifier may include: Prioritizing voice signals, Second priority in the MPEG header or the GOP header, Third order priority for MPEG I-frames, Multimedia packet transmission apparatus characterized by giving the lowest priority to the MPEG P-frame or B-frame. The method of claim 1, The packet data may include at least one of a video packet, a voice packet, a multimedia packet, and packet data having priority in one application service. In the packet transmission method for providing differentiated service level, A storing step of storing a QoS class, a policy for classifying packet data classes, and classifying result information according to the class or policy; DPI priority classification step of checking the priority information of the layer 3 or more multimedia packet data of the packet by using the stored classification classification result information, and assigns a suitable service class for each packet; And And displaying a service class in each multimedia data packet according to the classified service class. The method of claim 6, A measurement step of measuring a property of a transmitted packet according to the DPI priority and determining whether the packet satisfies a profile; A discarding step of discarding packets not satisfying the traffic profile as a result of the measurement; A stack removal step of preventing stacks that may cause packet loss and sorting them according to the grades indicated on the packet data; And And queuing step of sequentially storing the packet data for each service class arranged by the class and transmitting the packet data to an external network. The method of claim 6, The DPI priority classification step, A method of transmitting a multimedia packet, characterized in that the priority of the packet data is distinguished by searching not only the PT of the RTP header but also the priority field inside the PT of the actual multimedia packet. The method of claim 6, The DPI priority classification step in the case of the introduction of Voice over Internet Protocol (VoIP) and MPEG data packets, Prioritizing voice signals, Second priority in the MPEG header or the GOP header, Third order priority for MPEG I-frames, A method of transmitting a multimedia packet, characterized by giving the lowest priority to an MPEG P-frame or a B-frame. The method of claim 6, The packet data may include at least one of a video packet, a voice packet, a multimedia packet, and packet data having priority in one application service.

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