JP2004080523A - Packet relay device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize quality assurance suitable for multicast traffic. <P>SOLUTION: Identification information for identifying a transmission source or a destination of a muticast communication and parameters for designating communication quality to be provided to the multicast communication are previously correlated and registered in a policy table 46. When receiving a participation request message, containing the identification information for identifying the transmission source of destination of the multicast communication, a reservation acceptance processing section 45 determines whether or not the identification information contained in the participation request message is registered in the policy table. If the information is determined already registered, a traffic manager 35 is notified of the parameters corresponding to the identification information, and the communication quality designated by the parameters is assigned to the mutlicast communication identified by the identification information. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a packet relay device that forms a computer network for transmitting information in packet units and relays packets while selecting an optimal communication path. Related to the technology.
[0002]
[Prior art]
Among the computer networks, the Internet, which transmits information in packet units, uses a packet relay device (router) that selects and relays an optimal communication path based on identification information of a destination included in the packet, to transmit data between servers, Server terminals are connected.
[0003]
The packet relay device stores the received packet in the buffer, searches the routing table with the identification information of the destination included in the packet, selects the communication path closest to the destination, and reads the packet read from the buffer. Is transmitted to the selected communication path.
[0004]
In this way, in the Internet where packets are transmitted while being relayed by a packet relay device, the number of packets transmitted on the Internet varies greatly depending on the region and time because many unspecified persons use the packets at unspecified timing. Then, sometimes a packet exceeding the relay capability is locally generated.
[0005]
In such a case, packet discarding processing has been conventionally performed, but in recent years, there has been an increase in the number of businesses that provide information distribution services on the Internet for a fee, and communication quality that can transmit information to the other party without omission has been required. .
[0006]
This communication quality is generally called QoS (Quality of Service). To realize this QoS, two systems, IntServ (Integrated Service) and DiffServ (Differentiated Service), have been proposed to date. I was
[0007]
IntServ assigns a requested band and quality to each communication on a communication line like a digital leased line or an ATM, and the assignment of the band is performed by a control called RSVP (Resource reservation protocol). Protocol is used.
[0008]
In the bandwidth allocation procedure using RSVP, as shown in FIG. 16, first, a transmission node (terminal or server) 1 transmits a path message requesting a bandwidth required for information transmission to a reception node 2.
[0009]
This path message is relayed by a plurality of (here, three) packet relay devices 10a, 10b, and 10c on the network and transmitted to the receiving node 2. At this time, each of the packet relay devices 10a to 10c Remember the message.
[0010]
Then, the receiving node 2 prepares for receiving information based on the received path message, and returns a reserve message to the transmitting node 1 indicating that the preparation is completed.
[0011]
As shown in FIG. 17, the reserve message is relayed in the order of the packet relay devices 10c, 10b, and 10a and sent to the transmission node 1 in reverse to the transmission of the path message, and each of the packet relay devices 10a to 10c After confirming the reserve message from the node 2 side, the bandwidth requested by the previously stored path message is allocated for information transmission from the transmitting node 1 to the receiving node 2.
[0012]
The assignment of the bandwidth is specifically to set the capacity of the buffer, the read timing, and the transmission speed.
[0013]
As a result, a transmission path dedicated to a predetermined band is established between the transmission node 1 and the reception node 2, and thereafter information transmitted from the transmission node 1 at a speed corresponding to the predetermined band is transmitted between other nodes. Is reliably transmitted to the receiving node 2 without being affected by the communication information.
[0014]
On the other hand, the DiffServ method does not form a dedicated transmission channel of a predetermined band between a transmitting node and a receiving node unlike IntServ described above, but identifies a priority specified by a packet, The storage and reading of the buffer are controlled in accordance with the priority.
[0015]
That is, the TOS (Type of Service) area of the header of the IP packet is used as an area for marking a 6-bit code for identifying a traffic class.
[0016]
In each of the 64 classes identified by the 6-bit code, a combination of the traffic bandwidth and the delay is defined in advance, and the packet relay apparatus determines the quality corresponding to the class specified by the 6-bit code. Then, information transmission processing is performed.
[0017]
[Problems to be solved by the invention]
However, when trying to realize multicast by the above-mentioned RSPV method, signal processing of the packet relay device becomes complicated, and a large load is applied to the entire network.
[0018]
In the DiffServ method, although priority is provided to traffic, a quantitative bandwidth is not guaranteed, and therefore, when a lot of high-priority traffic occurs, the guarantee is insufficient.
[0019]
In particular, in recent years, with the spread of broadband access, a content delivery network (CDN) for distributing video to a large number of users has been spreading, and expectations for multicast distribution have been increasing.
[0020]
Moreover, in the video packet, relay transmission with less delay and jitter is required by UDP (User Datagram Protocol) without retransmission, and more reliable quality assurance is desired.
[0021]
The present invention has been made in view of such circumstances, and has as its object to provide a packet relay device that can realize quality assurance suitable for multicast traffic.
[0022]
[Means for Solving the Problems]
In order to achieve the above object, a packet relay device of the present invention comprises:
A packet relay device that stores a received packet in a buffer, and transmits a packet read from the buffer to a communication path corresponding to destination identification information included in the packet.
A policy table (46) in which identification information for specifying the transmission source or destination of the multicast communication and a parameter for specifying the communication quality to be given to the multicast communication are registered in advance in association with each other;
Means (45) for determining whether or not the identification information included in the participation request message is registered in the policy table when receiving a participation request message including identification information for specifying a transmission source or a destination of the multicast communication. When,
When it is determined that the identification information included in the participation request message is registered in the policy table, the communication quality specified by the parameter corresponding to the identification information is assigned to the multicast communication specified by the identification information. Means (45).
[0023]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a main part of a packet relay device 30 to which the present invention is applied.
[0024]
In FIG. 1, a network processor 31 performs classification of a packet input via an input / output interface (not shown), rewriting for routing, flow table creation processing, and the like. It has a flow management database 33 and a flow table 34.
[0025]
The packet classifier 32 refers to the flow table 34 and checks whether or not the received packet matches the flow table 34. If the packet is guaranteed, the queue dedicated to the flow (Queue, hereinafter simply Q ) Is output to the traffic manager 35 together with the packet. For packets not covered by the guarantee, the best effort queue (QID = 0) is output to the traffic manager 35 together with the packets.
[0026]
The flow table 34 is created based on the flow management database 33 in which information on traffic flows is stored. For example, as shown in FIG. 2, the identification information of the flow whose bandwidth is secured, that is, the destination It is composed of an IP address, a source IP address, a protocol, a destination port number, a source port number, and a QID for identifying a band allocated to those flows.
[0027]
The traffic manager 35 is for assigning quality assurance to traffic and performing scheduling processing. The traffic manager 35 has a plurality of sets of buffers 36, a packet scheduler 37, and a traffic management database 38 therein. The packet is stored in the buffer corresponding to the assigned QID.
[0028]
The packet scheduler 37 reads out the packets stored in the buffer dedicated to the guaranteed flow among the buffers 36 in accordance with the parameters stored in the traffic management database 38, and sends out the packets via an input / output interface (not shown). Packets stored in non-guaranteed buffers are read and transmitted by best-effort processing.
[0029]
In the traffic management database 38, for example, as shown in FIG. 3, information on a minimum rate, a maximum rate, a maximum delay, and an output port is set in advance for each QID.
[0030]
The IGMP / PIM reception processing unit 40 receives a join packet of IGMP (Internet Group Management Protocol) and PIM-SM (Protocol Independent Multicast-Sparse Mode) including a message of a request for participation in multicast communication, and a routing processing unit 41. , The multicast routing table 42 is created, and the join packet is notified to the reservation reception processing unit 45.
[0031]
The reservation reception processing unit 45 determines whether or not the identification information (address information) of the transmission source or the destination included in the participation request message of the multicast communication is registered in the policy table 46, and If so, the parameter corresponding to the identification information is notified to the traffic manager 35.
[0032]
In the policy table 46, for example, as shown in FIG. 4, a filter for extracting reservable traffic and a parameter specifying the quality required for the traffic are stored in association with each other. The contents stored in the policy table 46 are registered by the policy server 6 described later.
[0033]
The filter section of the policy table 46 is composed of data obtained by masking the destination IP address and the source IP address of the traffic, and the reservation reception processing section 45 performs processing on the destination IP address and the source IP address included in the notified packet. Then, the data of this filter is searched with data obtained by performing a predetermined masking process to determine whether or not the data is registered.
[0034]
Then, it is determined whether or not the traffic of the multicast communication requested by the notified join packet is the traffic for which the guarantee is requested. If the traffic is the traffic for which the guarantee is requested, the traffic management database 38 is checked. It is determined whether or not there is room to allocate more traffic.
[0035]
Specifically, assuming that the output ports of the traffic are P1 to Pn, the sum of the maximum rates of the queues in which the port of P1 is the output port of the traffic management database 38 is to be newly assigned from the line capacity of P1. If it is smaller than the result of reducing the maximum traffic capacity, the bandwidth of the traffic can be guaranteed.
[0036]
Similarly, the above calculation is performed for the ports P2 to Pn. If the bandwidth can be guaranteed for all the output ports, the information about the traffic is notified to the network processor 31 and the traffic manager 35, and the flow table 33, the traffic management database 38 Update.
[0037]
Next, the operation of the packet relay device 30 will be described.
First, an operation when the packet relay device 30 is connected to a transmission node that transmits multicast traffic will be described.
[0038]
As an initial setting, as shown in FIG. 5, the policy server 6 on the network in which the packet relay device 30 is present sends a policy P20 for one traffic to the packet relay device 30, that is, a destination address G, a source address S, Specify information including minimum rate, maximum rate, etc.
[0039]
The notification of the policy 20 by the policy server 6 is performed in response to a policy request from the packet relay device 30 side.
[0040]
In response, the packet relay device 30 creates the policy P20 in the policy table 46, and returns information indicating that the creation of the policy P20 has been successful to the policy server 6.
[0041]
In this state, when traffic is generated from the transmission node 1 as shown in FIG. 6, the packet relay device 30 creates a route cache for the traffic, but the distribution destination is registered in the routing table 42. Since this has not been done, this traffic is dropped. The flow information C1 for this traffic is registered in the flow table 34 as temporary QID = NULL (for example, NULL = −1).
[0042]
When a Join packet (PIM join) is sent from the packet relay device 30 ′ on the downstream side as shown in FIG. 7, the packet relay device 30 is requested for the flow C 1 registered in the flow table 34. Obtain the guaranteed parameters and check the assigned resources of the output port.
[0043]
Then, if the assignment is possible, as shown in FIG. 8, the route information is rewritten for the flow C1 in the routing table 42, the acquired parameter is registered as the QID 20 in the traffic management database 38, and the flow entry for the flow C1 is registered. Rewrite at the output destination (Q20).
[0044]
By the above process, as shown in FIG. 9, the traffic from the transmitting node 1 is relayed and transmitted to the downstream-side packet relay device 30 'while the band is guaranteed.
[0045]
Next, the operation of the packet relay device 30 on the receiving node 2 side as shown in FIG. 10 will be described.
[0046]
First, as shown in FIG. 10, the policy server 6 specifies the policy P20 to the packet relay device 30. At this time, the packet relay device 30 creates the policy P20 in the policy table 46, and returns information indicating that the creation has succeeded to the policy server 6.
[0047]
Then, as shown in FIG. 11, when receiving a join packet (IGMP Join) for requesting to participate in the multicast communication corresponding to the policy P20 from the receiving node 2, it acquires a guaranteed parameter and a route for the flow C1, and assigns an output port. Check for completed resources.
[0048]
Then, if the assignment is possible, as shown in FIG. 12, route information for the flow C1 is created in the routing table 42, and a join packet (PIM send).
[0049]
Next, as shown in FIG. 13, the flow entry for the flow C1 is rewritten at the output destination (Q20), and the parameter of the policy P20 read from the policy table 46 is assigned to the QID 20 of the traffic management database 38.
[0050]
By the above processing, as shown in FIG. 14, the traffic transmitted from the packet relay device 30 ″ on the upstream side is transmitted to the receiving node 2 with the bandwidth guaranteed.
[0051]
FIG. 15 is a flowchart illustrating the operation of the packet relay device 30 that has received a new join request message in a state where multicast communication is being performed by the above-described processing.
[0052]
The operation of the packet relay device 30 will be described with reference to this figure. First, multicast communication in which the destination address is G (group address) and the source address is S is received from the receiving node 1 or the packet relay device on the downstream side. When the join packet (IGMP / PIM-SM) for the participation request is sent, the packet relay device 30 searches the routing table 42 for an address (S, G), and the address is stored in the routing table 42. If there is, the interface number to which the receiving node 1 is connected is added to the routing table 42, and if not, it is newly generated (S1, S2).
[0053]
Then, it is checked whether or not there is a change in the distribution destination based on the combination of the addresses (S, G). If there is no change, the process ends as it is. It is checked whether or not there is a combination of addresses (S, G) in the policy table 46, and if there is such a combination, a parameter designating the guaranteed quality for the combination is read (S3 to S6).
[0054]
Then, it is determined whether or not the maximum rate of the read parameter can be secured at the output port. If it is determined that the maximum rate can be secured, a buffer corresponding to the parameter is allocated, and the traffic flow is registered in the flow table 34 (S7). ~ S9).
[0055]
Through this processing, traffic whose quality is guaranteed can be transmitted to the participation request source.
[0056]
When it is determined in step S5 that there is no combination of the addresses (S, G) in the policy table 46 and when it is determined in step S8 that the combination is not assigned, the traffic is subjected to the best effort processing. The buffer is registered in the allocation flow table (S10).
[0057]
In this case, traffic is transmitted to the participation request source in a normal relay mode in which quality is not guaranteed.
[0058]
Here, a case has been described in which a communication path whose quality is assured is formed with respect to the participation request message (join message). However, when a leaving request message (Leave message) is received, when a participation request message is received. The flow and queue are deleted and released by the reverse operation.
[0059]
【The invention's effect】
As described above, when a packet relay device of the present invention receives a participation request message including identification information for specifying a transmission source or a destination of multicast communication, the identification information included in the participation request message is stored in a policy table. Determine whether or not it is registered, when it is determined that it is registered, to allocate the communication quality specified by the parameter corresponding to the identification information to the multicast communication specified by the identification information I have.
[0060]
Therefore, complicated signal processing such as the RSVP method is not required, and a quantitative guarantee for multicast communication can be realized without imposing a large load on the network.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of a main part of an embodiment of the present invention. FIG. 2 is an example of data stored in a main part of the embodiment. FIG. 3 is an example of data stored in a main part of the embodiment. 4 Example of data stored in main part of embodiment [Fig. 5] Operation explanatory diagram of embodiment [Fig. 6] Operation explanatory diagram of embodiment [Fig. 7] Operation explanatory diagram of embodiment [Fig. 9 illustrates the operation of the embodiment. FIG. 10 illustrates the operation of the embodiment. FIG. 11 illustrates the operation of the embodiment. FIG. 12 illustrates the operation of the embodiment. FIG. FIG. 14 is an explanatory diagram of the operation of the embodiment. FIG. 15 is a flowchart of the main part of the embodiment. FIG. 16 is an explanatory diagram of the operation of the conventional system. FIG. 17 is an explanatory diagram of the operation of the conventional system. Description]
DESCRIPTION OF SYMBOLS 1 ... Sending node, 2 ... Receiving node, 6 ... Policy server, 30 ... Packet relay device, 31 ... Network processor, 32 ... Packet classifier, 33 ... Flow management database, 34 ... Flow table , 35 traffic manager, 36 buffer, 37 packet scheduler, 38 traffic management database, 40 IGMP / PIM reception processing unit, 41 routing processing unit, 42 routing table, 45 ... Reservation reception processing unit, 46 ... Policy table

Claims (1)

A packet relay device that stores a received packet in a buffer, and transmits a packet read from the buffer to a communication path corresponding to destination identification information included in the packet.
A policy table (46) in which identification information for specifying a transmission source or a destination of the multicast communication and a parameter for specifying communication quality to be given to the multicast communication are registered in advance in association with each other;
Means (45) for receiving, when receiving a participation request message including identification information specifying a transmission source or a destination of the multicast communication, identification information included in the participation request message registered in the policy table; When,
When it is determined that the identification information included in the participation request message is registered in the policy table, the communication quality specified by the parameter corresponding to the identification information is assigned to the multicast communication specified by the identification information. A packet relay device comprising means (45).

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