Distance-sensitive scheduling of TDM-over-packet traffic in VPLS
First Claim
Patent Images
1. A method of scheduling high-priority packets in a metro Ethernet switch, the method comprising the steps of:
- determining a maximum per-hop queuing delay allowed for at least two high-priority packets in a queue in the switch, wherein the maximum per-hop queuing delay for a particular one of said high-priority packets is a respective maximum per-hop queuing delay calculated dependent upon a number of hops in a label switched path (“
LSP”
) between the switch and a designated destination of the particular one of said high-priority packets and wherein said the respective maximum per-hop queuing delay is calculated only during set-up of the LSP and dependent upon a specified maximum end-to-end delay;
determining which one of the at least two high-priority packets has a smallest node exit delay requirement, wherein a node exit delay requirement for a designated high-priority packet is the sum of the maximum per-hop queuing delay allowed for the designated high-priority packet and a time of entry at the switch for the designated high-priority packet; and
scheduling the one of the at least two high-priority packets determined to have the smallest node exit delay requirement before the remaining ones of the at least two high-priority packets.
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Abstract
A method of scheduling high-priority packets in a metro Ethernet switch is described. In one embodiment, the method comprises the steps of determining a maximum queuing delay allowed for at least two high-priority packets in an output queue in the switch; determining which one of the at least two high-priority packets has the smallest maximum queuing delay allowed; and scheduling the one of the at least two high-priority packets determined to have the smallest maximum queuing delay allowed before the remaining ones of the at least two high-priority packets.
22 Citations
25 Claims
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1. A method of scheduling high-priority packets in a metro Ethernet switch, the method comprising the steps of:
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determining a maximum per-hop queuing delay allowed for at least two high-priority packets in a queue in the switch, wherein the maximum per-hop queuing delay for a particular one of said high-priority packets is a respective maximum per-hop queuing delay calculated dependent upon a number of hops in a label switched path (“
LSP”
) between the switch and a designated destination of the particular one of said high-priority packets and wherein said the respective maximum per-hop queuing delay is calculated only during set-up of the LSP and dependent upon a specified maximum end-to-end delay;determining which one of the at least two high-priority packets has a smallest node exit delay requirement, wherein a node exit delay requirement for a designated high-priority packet is the sum of the maximum per-hop queuing delay allowed for the designated high-priority packet and a time of entry at the switch for the designated high-priority packet; and scheduling the one of the at least two high-priority packets determined to have the smallest node exit delay requirement before the remaining ones of the at least two high-priority packets. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of scheduling high-priority packets in a metro Ethernet switch, the method comprising the steps of:
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creating a first table that lists, for each high-priority packet that has entered the switch, a position of the high-priority packet in a queue of the switch, a time the high-priority packet entered the queue, and an intended destination of the high-priority packet; creating a second table for storing a maximum allowed per-hop queuing delay for each of several possible intended destinations, wherein the maximum per-hop queuing delay for a particular one of said intended destinations is a respective maximum per-hop queuing delay calculated dependent upon a number of hops in a label switched path (“
LSP”
) between the switch and the particular one of said intended destination and wherein the respective maximum per-hop queuing delay is calculated only during set-up of the LSP and dependent upon a specified maximum end-to-end delay; andusing the first and second tables to determine a node exit delay requirement for each of the high-priority packets in the queue of the switch, wherein a node exit delay requirement for a designated high-priority packet is the sum of the maximum allowed per-hop queuing delay for the designated high-priority packet and a time of entry at the switch for the designated high-priority packet. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for scheduling high-priority packets in a metro Ethernet switch, the apparatus comprising:
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means for determining a maximum per-hop queuing delay allowed for at least two high-priority packets in a queue in the switch, wherein the maximum per-hop queuing delay for a particular one of said high-priority packets is a respective maximum per-hop queuing delay calculated dependent upon a number of hops in a label switched path (“
LSP”
) between the switch and a designated destination of the particular one of said high-priority packets and wherein said the respective maximum per-hop queuing delay is calculated only during set-up of the LSP and dependent upon a specified maximum end-to-end delay;means for determining which one of the at least two high-priority packets has smallest node exit delay requirement, wherein a node exit delay requirement for a designated high-priority packet is the sum of the maximum per-hop queuing delay allowed for the designated high-priority packet and a time of entry at the switch for the designated high-priority packet; and means for scheduling the one of the at least two high-priority packets determined to have the smallest node exit delay requirement before the remaining ones of the at least two high-priority packets. - View Dependent Claims (17, 18, 19, 20, 21)
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22. A packet switch comprising:
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a queue containing a plurality of packets received at the switch; and a scheduler for scheduling transmission of the packets in the queue, wherein when the queue contains at least two high-priority packets, the scheduler schedules the one of the at least two high-priority packets determined to have a smallest node exit delay requirement before the remaining ones of the at least two high-priority packets, wherein a node exit delay requirement for a designated high-priority packet is the sum of a maximum per-hop queuing delay allowed for the designated high-priority packet and a time of entry at the switch for the designated high-priority packet, wherein the maximum per-hop queuing delay for a particular one of said high-priority packets is a respective maximum per-hop queuing delay calculated dependent upon a number of hops in a label switched path (“
LSP”
) between the switch and a designated destination of the particular one of said high-priority packets and wherein said the respective maximum per-hop queuing delay is calculated only during set-up of the LSP and dependent upon a specified maximum end-to-end delay. - View Dependent Claims (23, 24, 25)
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Specification