Method for overload control in a packet switch that processes packet streams having different priority levels
First Claim
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1. A system for controlling overload for use in a packet processing system, said system comprising:
- a polled packet stream;
an interrupt-driven packet stream that generates an interrupt when a packet is available for processing;
a counter associated with said interrupt-driven packet stream;
a common destination for packets from both said interrupt-driven packet stream and said polled packet stream; and
control means for processing packets from both said interrupt-driven packet stream and said polled packet stream by processing packets from said polled packet stream and preempting processing of packets from said polled packet stream when an interrupt is received from said interrupt-driven packet stream in order to process packets from said interrupt-driven packet stream and for delivering said packets to said common destination, wherein said processing includes decrementing said counter each time said control means receives a packet from said interrupt-driven packet stream, and, when said counter reaches a predetermined number, disabling interrupts so that said interrupt-driven packet stream stops preempting said polled packet stream and processing a predetermined number of packets from said polled packet stream before resetting said counter and allowing interrupts from said interrupt-driven packet stream to preempt delivery of packets from said polled packet stream again.
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Abstract
A system and method that controls potential overload of packet switches when the packet switch has multiple packet streams with different priority levels. A counter is associated with the higher priority packet stream, so that when the counter reaches a predetermined number, the higher priority packet stream is disabled, so that the lower priority packet stream may be processed. When the counter reaches the predetermined number, interrupts are disabled, thus inhibiting processing of the higher priority packet stream. Advantageously, a predetermined number of polled packets are processed before interrupts are enabled.
102 Citations
10 Claims
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1. A system for controlling overload for use in a packet processing system, said system comprising:
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a polled packet stream; an interrupt-driven packet stream that generates an interrupt when a packet is available for processing; a counter associated with said interrupt-driven packet stream; a common destination for packets from both said interrupt-driven packet stream and said polled packet stream; and control means for processing packets from both said interrupt-driven packet stream and said polled packet stream by processing packets from said polled packet stream and preempting processing of packets from said polled packet stream when an interrupt is received from said interrupt-driven packet stream in order to process packets from said interrupt-driven packet stream and for delivering said packets to said common destination, wherein said processing includes decrementing said counter each time said control means receives a packet from said interrupt-driven packet stream, and, when said counter reaches a predetermined number, disabling interrupts so that said interrupt-driven packet stream stops preempting said polled packet stream and processing a predetermined number of packets from said polled packet stream before resetting said counter and allowing interrupts from said interrupt-driven packet stream to preempt delivery of packets from said polled packet stream again. - View Dependent Claims (2, 3, 4, 5)
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6. A method for controlling overload for use in a packet processing device, said packet processing device receiving packets from a plurality of sources, at least one of said plurality of sources providing an interrupt when there is a packet to be processed and at least one other of said plurality of sources being polled, said method comprising the steps of:
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processing packets from said interrupt source responsive to an interrupt wherein said processing includes preempting processing of packets from said polled source; decrementing a counter for each packet processed which is associated with said interrupt source; responsive to said counter reaching a predetermined number, disabling interrupts so that packets associated with said interrupt source are not processed; processing at least one packet from said polled packet source; resetting said counter; and enabling interrupts and repeating the steps of processing packets from said interrupt source responsive to an interrupt, decrementing said counter and disabling interrupts when said counter reaches said predetermined number. - View Dependent Claims (7, 8, 9, 10)
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Specification