Source: http://www.freepatentsonline.com/y2012/0320750.html
Timestamp: 2019-01-19 18:27:07
Document Index: 534185301

Matched Legal Cases: ['art 1', 'art 1', 'art 1', 'art 1', 'art 2', 'art 2', 'art 1', 'art 2', 'art 2', 'art 1', 'art 2', 'art 2']

BANDWIDTH MONITORING METHOD AND ITS DEVICE - HITACHI, LTD.
United States Patent Application 20120320750
Yazaki, Takeki (Hachioji, JP)
Aimoto, Takeshi (Santa Clara, CA, US)
13/597470
H04L12/26; H04L29/14; H04L12/801; H04L12/813; H04L12/851; H04L12/911; H04Q11/04
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1. A packet transmission apparatus connected to a network in which specific type of packets are transmitted in preference to packets other than the specific type of packets, comprising: a flow detection unit for judging whether each of inputted packets is the specific type of packet or not; a packet transmission unit for transmitting the inputted packet; and a bandwidth checking unit for checking whether the inputted packet violates a contract bandwidth contracted with a source of the inputted packet regardless of whether the inputted packet is of the specific type or not, wherein when the flow detection unit judges the inputted packet is a packet other than the specific type of packets in a state where the specific type of packets do not violate the contract bandwidth and the inputted packet does not violate the contract bandwidth, the packet transmission unit writes a specific value indicative of the specific type of packet in a header of the inputted packet.
This is a continuation application of U.S. Ser. No. 12/553,202, filed Sep. 3, 2009, which is a continuation of U.S. Ser. No. 10/874,219, filed Jun. 24, 2004, which is continuation application of U.S. Ser. No. 09/585,389, filed Jun. 2, 2000 (now U.S. Pat. No. 7,340,529), which claims priority to JP 11-154657, filed Jun. 2, 1999. The entire disclosures of all of the above-identified applications are hereby incorporated by reference.
As a prior art related to QoS, there is known, for example, a Diffsery (Differentiated Service) (hereinafter called prior art 1) described in RFC2475 of IETF (Internet Engineering Task Force). The prior art 1 describes that traffics (packets) are divided into classes by a source/destination IP address, a source/destination port number, a protocol, etc. in a TCP/IP header at an entrance of a network which provides services, and forwarding operations are assigned thereto. Further, the prior art 1 also describes that each packet is transferred based on a transfer or forwarding operation related to a DSCP (Differentiated Service Code Point) in a header in the network.
The bandwidth monitoring device having the bandwidth monitoring function according to the prior art 1 judges voice packets lying within a monitoring bandwidth as priority packets, and voice packets at the monitoring bandwidth or higher and packets other than the voice packets as non priority packets. When traffics sent out by a user are shown in FIG. 8(a), traffics subsequent to the passage of the bandwidth monitoring function are represented as shown in FIG. 8(b). Packets other than the voice packets indicated by diagonally-shaded portions shown in FIG. 8(b) are transmitted as non priority packets regardless of the fact that the priority packets fall within the monitoring bandwidth. Namely, the user is not able to sufficiently use the contract bandwidth for each priority packet.
On the other hand, even the prior art 2 will cause a problem similar to the above. The bandwidth monitoring device having the bandwidth monitoring function according to the prior art 2 transmits only cells with CLP=0 within the monitoring bandwidth as CLP=0. When traffics sent out by a user are given as shown in FIG. 15(a), traffics subsequent to the passage of the bandwidth monitoring function are represented as shown in FIG. 15(b). Cells corresponding to the diagonally-shaded portions in FIG. 15(b) are transmitted as cells with CLP=1 regardless of the fact that the amount of cells with CLP=0 is within the limit of the monitoring bandwidth. Namely, the user is not able to sufficiently utilize a contract bandwidth with CLP=0.
FIG. 8(a) is a diagram showing the variation with the passage of time in traffics of voice packets and the other packets transmitted from an enterprise network A210;
FIG. 8(b) is a diagram showing the variation with the passage of time in traffics after passing through a bandwidth monitoring unit to which the prior art 1 is applied;
FIG. 8(c) is a diagram showing the variation with the passage of time in traffics after passing through a router having the bandwidth monitoring unit 141 to which the present invention is applied;
FIG. 13(a) is a diagram showing the variation with the passage of time in traffics of priority packets and non priority packets transmitted from the enterprise network A210;
FIG. 13(b) is a diagram showing the variation with the passage of time in traffics after passing through a bandwidth monitoring unit to which the prior art 2 is applied;
FIG. 13(c) is a diagram showing the variation with the passage of time in traffics after passing through a router having the bandwidth monitoring unit 941 to which the present invention is applied;
FIG. 15(a) is a diagram showing the variation with the passage of time in traffics of CLP=0 and CLP=1 transmitted from the enterprise network A210;
FIG. 15(b) is a diagram showing the variation with the passage of time in traffics after passing through a bandwidth monitoring unit to which the prior art 2 is applied; and
FIG. 15(c) is a diagram showing the variation with the passage of time in traffics after passing through a bandwidth monitoring unit to which the present invention is applied.
FIG. 2 shows a network wherein enterprise networks A:210, B:220, C:230 and D:240 are connected to one another by an Internet 200. The Internet 200 comprises edge routers A:202 and B: 203 located at edges of the network, and a backbone router 201 located at a core thereof. Gateway routers A:211, B:221, C:231 and D: 241 are placed in gateways to the Internet 200 within the enterprise networks A:210, B:220, C:230 and D:240.
The Leaky Bucket Algorithm is a model of certain depth of leakage bucket with a hole. While the bucket is storing water therein, water leaks at a predetermined rate corresponding to a monitoring bandwidth, and a fixed amount or level of water corresponding to one cell is poured into the bucket upon arrival of each cell. The bucket has a depth for the purpose of allowing fluctuations of cell arrival.
When the water is not overflowing the bucket, input cells are judged to comply with a contract bandwidth. If the water overflows the bucket, input cells are judged to violate the contract bandwidth. In the invention of the present application, the monitoring of the bandwidth for variable length packets is achieved by varying the amount of water to be poured into the bucket depending upon a arrival packet.
The flow detection unit 540 is a functional part inherent in a router. In an ATM switch, a connection is established in advance, and bandwidth monitoring control information is readout according to a connection identifier of each input cell. Further, the bandwidth monitoring unit executes bandwidth monitoring through the use of the bandwidth monitoring control information (connection communication). On the other hand, since no connection is established in advance in a router device, the router device needs to have flow detecting means for determining a flow identifier used as an alternative to the connection identifier for each input packet according to information or the like lying within a header with a view toward performing the bandwidth monitoring by the router device (connectionless communication). The router reads out bandwidth monitoring control information corresponding to the flow identifier and executes the bandwidth monitoring by using the bandwidth monitoring control information.
FIG. 6 shows a format of the bandwidth check table 550. The bandwidth monitoring or check table 550 has N bandwidth check information entries 600-1 to 600-N. The bandwidth monitoring unit 141 effects bandwidth monitoring on one or more flows which share the use of a bandwidth, according to one of bandwidth check control information entries 600-j (where j=1 to N). In the present embodiment, a flow of voice packets sent by the enterprise network A210 and a flow of packets other than the voice packets are monitored at a contract bandwidth according to one of said bandwidth check control information entries 600-j.
Each of bandwidth check control information entries 600-j comprises a threshold-A (THR-A) 601-j (Byte) indicative of a depth of bucket for packets to which a flow priority to be described later is given as priority, a threshold-B (THR-B) 602-j (Byte) indicative of a depth of bucket for packets with non priority, a policing rate (POLR) 603-j (Byte/sec) indicative of a leakage rate of a bucket, i.e., a monitoring or check rate, a time stamp (TS) 604-j (sec) indicative of the previous arrival time of a packet which refers to the same bandwidth check control information entry 600-j, a count (CNT) 605-j (Byte) indicative of the amount or level of water stored in the bucket immediately after the bandwidth monitoring of the previous packet, a DSCP conformance (DSCPC) 606-j indicative of a DSCP of a packet judged as conformance by the bandwidth monitoring and transferred as a priority packet, and a DSCP non-conformance (DSCPN) 607-j indicative of a DSCP of a packet judged as non-conformance and transferred as a non priority packet. Incidentally, the THR-A 601-j and THR-B 602-j each indicative of the depth of the bucket satisfy the relations in THR-A 601-j THR-B 602-j.
When the bandwidth monitoring unit 141 receives packet header information 11, a packet length storage 522 of the check result decision unit 520 stores a packet length 331 therein, and the flow detection unit 540 stores a SIP 311, a DIP 312, a SPORT 313 and a DPORT 314 therein (Step 701).
In Step 702, the flow detection unit 540 performs flow detection based on the stored information and judges or determines a flow identifier corresponding to an identifier of a flow for each input packet, and a flow priority which indicates the priority of packets within the flow. Thus, the flow detection unit 540 transmits flow identifier information 14 comprised of the flow identifier to the bandwidth check table control circuit 561 of the bandwidth check table control unit 560 and transmits flow priority information 17 comprised of the flow priority to a flow priority storage 524 of the check result decision unit 520. In the present embodiment, the flow priority of voice packet is defined as priority and the flow priority of the other packets are defined as non priority so that voice packets are preferentially judged as the priority packets.
The bandwidth monitoring device having the bandwidth monitoring function, according to the prior art 1, determines voice packets within a monitoring bandwidth (contract bandwidth) as priority packets while judging surplus voice packets over the monitoring bandwidth and packets other than the voice packets as non priority packets. When the traffics shown in FIG. 8(a) are inputted, the traffics observed after the prior art bandwidth monitoring are represented as shown in FIG. 8(b). Packets other than voice packets indicated by diagonally-shaded portions shown in FIG. 8(b) are transmitted as non priority packets regardless of the fact that the real amount of priority packets stays within the monitoring bandwidth. Namely, a manager of the enterprise network A210 is not able to sufficiently utilize the contract bandwidth for the priority packets.
Since the bandwidth monitoring unit 141 according to the present invention is newly provided with a threshold THR-B 602-j, it is able to judge some amount of packets other than voice packets as priority packets when the bandwidth of the received voice packets is below the contract bandwidth and the bucket water level is less than the THR-B 602-j. Traffics observed after passing through the bandwidth monitoring by the bandwidth monitoring unit 141 of the present invention are shown in FIG. 8(c), which indicates that the manager of the enterprise network A210 can sufficiently utilize the contract bandwidth.
In FIG. 2, it is assumed that the bandwidth for the priority packets is contracted between the Internet 200 and the enterprise network A: 210, and the gateway router A: 211 transmits priority packets and non priority packets in distinction from one another according to DSCP as shown in FIG. 13(a). The edge router A: 202 performs bandwidth monitoring to carry out an re-assignment of the DSCP. A router 100 having the bandwidth monitoring unit 141 to which the present invention is applied, is used as the edge router A: 202.
Since the DSCP of each non priority packet is not changed in the prior art 2 even when the gateway router A: 211 does not transmit the priority packets, the manager of the enterprise network A: 210 could not effectively utilize the contract bandwidth (see FIG. 13(b)). On the other hand, when the router 100 provided with the bandwidth monitoring unit 141 according to the present invention is used as the edge router A: 202, the manager of the enterprise network A: 210 can effectively utilize the contract bandwidth owing to a rise in priority of the DSCP of the non priority packets when the gateway router A: 211 transmits priority packets at a rate less than the contract bandwidth (see FIG. 13(c)).
Although the priority of the network has been described while being limited to the DSCP of the IP header, a CLP (Cell Loss Priority) bit lying within a header of ATM cell and a DE (Delete Enable) bit lying within a frame header of a frame relay can be also treated in a manner similar to the DSCP. Traffics in a customer marking case in which the gateway router A: 211 effects marking on the CLP of the ATM cells are shown in FIG. 15(a), traffics after the bandwidth monitoring according to the prior art 2 are shown in FIG. 15(b), and traffics after passing through the edge router A: 202 to which the present invention is applied are shown in FIG. 15(c).
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