IPC분류정보
국가/구분 |
United States(US) Patent
등록
|
국제특허분류(IPC7판) |
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출원번호 |
US-0572955
(2000-05-18)
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우선권정보 |
JP-0141164 (1999-05-21) |
발명자
/ 주소 |
- Kohzuki, Kiyoshi
- Aimoto, Takeshi
- Sakata, Yoshihiko
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출원인 / 주소 |
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대리인 / 주소 |
Mattingly, Stanger, Malur &
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인용정보 |
피인용 횟수 :
52 인용 특허 :
9 |
초록
▼
A packet forwarding device with a shaping unit, which is provided with queues for storing high priority packets and queues for storing low priority packets. The shaping unit transmits a packet read out from the non priority queue by giving a high priority when no transmit-wait packet exist in the pr
A packet forwarding device with a shaping unit, which is provided with queues for storing high priority packets and queues for storing low priority packets. The shaping unit transmits a packet read out from the non priority queue by giving a high priority when no transmit-wait packet exist in the priority queue even though the time to transmit a packet from the priority queue is reached.
대표청구항
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1. A packet forwarding device connected to a packet forwarding network, comprising:a packet transmission unit for determining a transmit destination by referring to destination information described in a header of each of received packets; and a plurality of line interfaces each corresponding to the
1. A packet forwarding device connected to a packet forwarding network, comprising:a packet transmission unit for determining a transmit destination by referring to destination information described in a header of each of received packets; and a plurality of line interfaces each corresponding to the type of connected line; at least one of said line interfaces having a traffic shaping unit, said traffic shaping unit comprising: priority queues prepared for each output destination for storing therein packets to be transmitted within a guaranteed bandwidth, which are received from said packet transmission unit; non priority queues prepared for each output destination for storing therein packets to be transmitted at a bandwidth other than the guaranteed bandwidth, which are received from said packet transmission unit; a queue decision circuit having the function of determining priority by referring to user information and information about priorities both described in the header of each of packets received from said transmission unit and queuing the packet into on either of a priority queue or a non priority queue for each output destination; a scheduled transmission time calculator for calculating a scheduled transmission time for a leading one of transmit-wait packets for each of said queues; a scheduled transmission time storage for storing therein the scheduled transmission time for each of said queues and a scheduled transmission time for one of said queues from which a packet should be transmitted with the highest priority, each of said scheduled transmission times having been calculated by said scheduled transmission time calculator; a sorting circuit for selecting a queue from which a packet should be transmitted with the highest priority by referring to the scheduled transmission times for each of said queues stored in said scheduled transmission time storage; a packet read out circuit for reading out packets from said queues in accordance with the scheduled transmission time for each of said queues stored in said scheduled transmission time storage and transmitting the same to a line connected with the line interface; and a priority information supplement circuit for writing information about priorities in a header of the packet read out by said packet read out circuit. 2. The packet forwarding device according to claim 1, wherein said priority queue exists in plural form with respect to the same output destination, and priorities are assigned to the plurality of queues, andsaid packet read out circuit reads out a packet from a queue highest in priority from among the queues in which transmit-wait packets exist, and transmits the read out packet therefrom. 3. The packet forwarding device according to claim 1, wherein said non priority queue exists in plural form with respect to the same output destination, and priorities are assigned to the plurality of queues, andsaid packet read out circuit reads out a packet from a queue highest in priority from among the queues in which transmit-wait packets exist, and transmits the read out packet therefrom. 4. The packet forwarding device according to claim 1, wherein said non priority queue exists in plural form with respect to the same output destination, and priorities are assigned to the plurality of queues,said packet read out circuit reads out a packet from a queue highest in priority from among the queues in which transmit-wait packets exist, and transmits the read out packet therefrom, and said priority information supplement circuit amends the priority of the queue from which said packet is read out, to the lowest priority. 5. The packet forwarding device according to claim 1, wherein said scheduled transmission time calculator is provided with a first circuit for calculating a scheduled transmission time so as to continuously read out packets, a second circuit for calculating a scheduled transmission time so as to keep a guaranteed bandwidth, and a selector for selecting either of the results of calculations by said first and second circuits as a scheduled transmission time.6. The packet forwarding device according to claim 5, wherein said selector has the function of selecting the result of calculation by said first circuit for calculating the scheduled transmission time so as to continuously read out packets when the line interface receives a packet,selecting the result of calculation by said second circuit for calculating the scheduled transmission time so as to keep the guaranteed bandwidth when the line interface transmits a packet from said priority queue, and selecting the result of calculation by said first circuit for calculating the scheduled transmission time so as to continuously read out each packet when the line interface transmits a packet from said non priority queue. 7. The packet forwarding device according to claim 6, wherein a threshold is set to each of said priority queues in advance, and said selector selects the result of calculation by said second circuit for calculating the scheduled transmission time so as to keep the guaranteed bandwidth when the number of packets stored in the priority queue does not exceed the threshold, and selects the result of calculation by said first circuit for calculating the scheduled transmission time so as to continuously read out each packet when the number of packets stored in the priority queue exceeds the threshold.8. The packet forwarding device according to claim 1, wherein said priority information supplement circuit writes priority information indicative of a high priority into a header of a read out packet when the packet is read out from said priority queue by said packet read out circuit, andsaid priority information supplement circuit writes priority information indicative of a low priority into a header of a read out packet when the packet is read out from said non priority queue by said packet read out circuit. 9. The packet forwarding device according to claim 1, wherein said priority information supplement circuit writes priority information indicative of a high priority into a header of a read out packet when the transmit-wait packets do no exist in said priority queue at the scheduled transmission time for said priority queue and a packet is transmitted from said non priority queue.10. The packet forwarding device according to claim 8, wherein said priority information supplement circuit changes the value of a TOS area within a header of an IP packet as said priority information.11. The packet forwarding device according to claim 8, wherein said priority information supplement circuit changes the value of a CLP bit within a header of an ATM cell as said priority information.12. The packet forwarding device with a shaping unit, wherein said shaping unit including, for users, a priority queue for storing high priority packets; and a non priority queues for storing low priority packets whereinsaid shaping unit further including a scheduled transmission time calculator for setting a scheduled transmission time to a leading packet among transmit-wait packets stored in each of said priority queues so as to keep a guaranteed bandwidth, setting an immediately transmitted time as a scheduled transmission time of a leading packet among transmit-wait packets stored in each of said non priority queues, and setting a scheduled transmission time corresponding to a transmission bandwidth integrating said priority queue and non priority queue. 13. The packet forwarding device according to claim 12, further including a priority information supplement circuit for giving a high priority to a packet read out from each of said priority queues and giving a low priority to a packet read out from each of said non priority queues.14. The packet forwarding device according to claim 13, wherein said scheduled transmission time calculator refers to a queue length of the priority queue upon calculation of a scheduled transmission time for the priority queue, and sets an immediately transmitted time as the scheduled transmission time without keeping a guaranteed bandwidth when packets exceeding a predetermined amount are stored.15. A packet priority setting method, comprising the steps of:reading out a transmit-wait packet from a non priority queue when no transmit-wait packet exists in a priority queue even though the time to transmit a packet from the priority queue is reached; and giving a high priority to the transmit-wait packet read out from the non priority queue.
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