US 6,912,225 B1Granted

Packet forwarding device and packet priority setting method

AssigneeHitachi, Ltd.

InventorsKiyoshi Kohzuki, Takeshi Aimoto, Yoshihiko Sakata

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Abstract

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.

Claims15

Dependent claims

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.

10 more elements

Dependencies are inferred from the claim text.

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Abstract

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.

10 more elements