Packet scheduling device

• US 6,754,215 B1
• Filed: 08/15/2000
• Issued: 06/22/2004
• Est. Priority Date: 08/17/1999
• Status: Active Grant

• Current Assignee: Rakuten Group, Inc.
• Original Assignee: NEC Corporation
• Inventors: Nishihara, Motoo, Arikawa, Toshiaki, Masuda, Michio
• Primary Examiner(s): VANDERPUYE, KENNETH N
• Application Number:
  US09/638,878
• Time in Patent Office: 1,407 Days
• Field of Search: 370/395.4, 370/395.1, 370/389, 370/395.41, 370/395.42, 370/395.43
• US Class Current: 370/395.4
• CPC Class Codes: H04L 12/5601 Transfer mode dependent, e.g. ATM
• CPC Class Codes: H04L 2012/5651 Priority, marking, classes
• CPC Class Codes: H04L 2012/5679 Arbitration or scheduling
• CPC Class Codes: H04L 47/24 Traffic characterised by specific attributes, e.g. priority or QoS
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 47/50 Queue scheduling

Abstract

In the packet scheduling device, the output class selection part is made to conduct the selective output of priority class, based on the weight count value calculated from a weight value corresponding to minimum guarantee bandwidth for each priority class and the amount of packet accumulated in each queue. The output class selection part operates so that if the weight count value is “0” or more, then the packet length of variable-length packet data to be output is subtracted from the current weight count value to give a renewed weight count value. On the other hand, if the weight count value is less than “0”, until reaching a predetermined repeat count (Cmax−1), the weight value of each priority class is added to the weight count value of all priority classes, and, when reaching the repeat count (Cmax−1), the weight value is added to the weight count value of all priority classes or replaced by half the weight value. Thereby, the weight count value is made to be more than “0”, and the values thus renewed are subject to the rule of round robin so as to select the priority class.

Claims

1. A packet scheduling device, comprising:

a plurality of packet accumulating means for accumulating one or more variable-length packets with a preset priority class corresponding to one of a plurality of priority classes;

a plurality of weight count means for renewing a weight count value every predetermined unit of selection processing, said weight count means being provided corresponding to said plurality of packet accumulating means, the weight count value being a priority class selection information;

a priority class selecting means for selecting one priority class from priority classes with said weight count value of zero or more in said selection processing according to a round robin to select equally in turn each priority class;

a selection processing repeat-count monitoring means for monitoring a repeat count of said unit of selection processing to be conducted for each priority class;

a renewal instructing means for instructing said plurality of weight count means to renew said weight count value for each priority class so as to allow said weight count value to have zero or more when the repeat count monitored by said unit of selection processing repeat-count monitoring means reaches a predetermined value; and

a packet reading means for reading a variable-length packet accumulated in one of said packet accumulating means corresponding to the priority class selected by said priority class selecting means.

5. A packet scheduling device, according to claim 1, further comprising:

a repeat-count setting means for setting said predetermined value as a maximum value of said selection processing repeat count.

2. A packet scheduling device, comprising:

a plurality of packet accumulating means for accumulating one or more variable-length packets with a preset priority class corresponding to one of a plurality of priority classes;

a plurality of weight count means for renewing a weight count value by subtracting the length of a variable-length packet when said packet accumulating means outputs the variable-length packet, and for renewing the weight count value based on a weight value corresponding to minimum guarantee bandwidth of the priority class according to a predetermined renewal instruction signal, said weight count means being provided corresponding to said plurality of packet accumulating means;

a selection processing repeat-count monitoring means for monitoring a repeat count of a unit of selection processing to be conducted for each priority class;

a priority class selecting means for selecting one priority class from priority classes with said weight count value of zero or more in said unit of selection processing according to a round robin to select equally in turn each priority class;

a renewal instructing means for instructing all said plurality of weight count means to renew said weight count value for each priority class so as to allow said weight count value to have a value determined based on the weight value set for each priority class when the repeat count monitored by said selection processing repeat-count monitoring means reaches a predetermined value and the renewed weight count value is less than zero; and

a packet reading means for reading a variable-length packet accumulated in one of said packet accumulating means corresponding to the priority class selected by said priority class selecting means.

3. A packet scheduling device, according to claim 2, wherein:

said renewal instructing means instructs all said plurality of weight count means to renew said weight count value for each priority class so as to allow said weight count value to have a value of zero or more that is selectable by said priority class selecting means when the repeat count monitored by said selection processing repeat-count monitoring means reaches a predetermined value and the renewed weight count value is less than zero.

4. A packet scheduling device, according to claim 2, further comprising:

a priority class identifying means for identifying a priority class based on priority class information added in advance to a variable-length packet and for storing the packet into said corresponding packet accumulating means;

wherein said plurality weight count means renews a weight count value by subtracting a length of variable-length packet recognized from packet length information added in advance to a variable-length packet accumulated in corresponding one of said packet accumulating means.

6. A packet scheduling device, according to claim 2, further comprising:

a repeat-count setting means for setting said predetermined value as a maximum value of said selection processing repeat count.