US 6,147,970 A · Quality of service management for aggregated flows in a network system

Abstract

A system and method for optimizing data flow through a node in a network system, where messages forwarded to the node have one of at least two priorities, a normal priority and a high priority. A novel token bucket approach allows maintaining Quality of Service (Qos) while maximizing throughput. Token buckets include normal and high-priority levels, which reserve capacity for high priority bursts of data. Messages for which not enough tokens are present are marked as not protected against loss, and dropped or sent on depending on a mode. Two-stage policing using two levels of token buckets is also presented. Each flow into a node or router has an associated token bucket, with normal and high priority levels. A second aggregate token bucket then re-tests all messages which were considered protected against loss from the first stage. Messages can be marked not protected against loss and sent out appropriately (for example, marked CLP-1 in an ATM VBR-tagged system), or dropped. Also, messages which were marked not protected against loss at the first stage can be marked protected against loss based on a headroom threshold, which allows excess token bucket capacity to be used passing messages which would normally be dropped.

Claims15

Dependent claims

A system for optimizing data flow through a node in a network system, wherein messages forwarded to said node have one of at least two priorities, a normal priority and a high priority, said system comprising:

a first stage, including for each flow into said node:
a token counter associated with each flow into said node, each token counter for holding a numeric value representing a number of tokens, said token counter being incremented at a predetermined rate of tokens per second, and said token counter being decremented by a number of tokens as required for passing an arriving message in that flow through said node, said number of tokens required for passing said arriving message being determined by attributes of said arriving message, said token counter further including a maximum limit value;
a normal priority threshold value associated with each token counter;
wherein if a message with a high priority arrives at said node, said message is marked not protected against loss if said token counter is below said number of tokens required for passing said message;
and
wherein if a message with a normal priority arrives at said node, said message is marked not protected against loss if said token counter is below said number of tokens required for passing said message plus said normal priority threshold value.

3 more elements

A method for optimizing data flow through a node in a network system, wherein messages arriving on flows to said node have one of at least two priorities, a normal priority and a high priority, said method comprising:

for each data flow into said node:
providing a token counter associated with each data flow, each token counter for holding a numeric value representing a number of tokens, said token counter further including a maximum limit value;
incrementing said token counter at a predetermined rate of tokens per second;
decrementing said token counter by a number of tokens as required for passing an arriving message in that data flow through said node, said number of tokens required for passing said arriving message being determined by attributes of said arriving message;
providing a normal priority threshold value associated with each token counter;
and
marking a message with a high priority as not protected against loss if said token counter is below said number of tokens required for passing said message;
and
marking a message with a normal priority as not protected against loss if said token counter is below said number of tokens required for passing said messages plus said normal priority threshold value.

6 more elements

Dependencies are inferred from the claim text.

Quality of service management for aggregated flows in a network system

Life of this patent

Quality of service management for aggregated flows in a network system

Life of this patent

Abstract

Claims15