USING BANDWIDTH MEASUREMENTS TO ADJUST CIR AND EIR ON A SUB-RATE LINK

1 . A method for measuring the bandwidth of a network segment between a first location and a second location, comprising

generating a plurality of synthetic packets at the first location and marking each generated synthetic packet with a transmission timestamp indicative of a first clock time at which the synthetic packet is generated,

transmitting each of the generated synthetic packets said second location,

receiving each synthetic packet at the second location and marking each received synthetic packet with a reception timestamp indicative of a second clock time at which the synthetic packet is received at the second location,

calculating an inter-packet delay variation of the network segment based on the transmission timestamp and the reception timestamp of two or more synthetic packets, and

deriving an available bandwidth of the network segment based on the calculated inter-packet delay variation.

2 . The method of claim 1 wherein said derived available bandwidth is used to trigger one or more actions.

3 . The method of claim 2 wherein said one or more actions comprises changing the configuration of traffic shapers for said network segment.

4 . The method of claim 1 wherein the deriving of said available bandwidth takes into account one or more previously calculated inter packet delay variations.

5 . The method of claim 1 wherein each of said plurality of synthetic packets has the same predetermined number of bytes.

6 . The method of claim 1 wherein said plurality of synthetic packets are transmitted substantially consecutively.

7 . The method of claim 1 , in which said calculating the inter packet delay variation comprises

calculating a first delay as a difference between the reception timestamp and the transmission timestamp for a first of said plurality of synthetic packets,

calculating a second delay for a second synthetic packet as a difference between the reception timestamp and the transmission timestamp for the second of said plurality of synthetic packets, and

setting the inter packet delay variation as the difference between said second delay and said first delay.

8 . A method according to claim 1 , in which said deriving an available bandwidth of the network segment comprises

multiplying a number of bytes in a first synthetic packet by the rate of a first link in said network segment and adding the calculated inter packet delay variation for said first synthetic packet, and

dividing the resulting sum by a number of bytes in said synthetic packet.

9 . A system for measuring the bandwidth of a network segment between a first location and a second location, said system comprising

a first processor adapted to

generate a plurality of synthetic packets at the first location and mark each generated synthetic packet with a transmission timestamp indicative of a first clock time at which the synthetic packet is generated, and

transmit each of the generated synthetic to said second location, and

a second processor adapted to

receive each synthetic packet at the second location and mark each received synthetic packet with a reception timestamp indicative of a second clock time at which the synthetic packet is received at the second location,

calculate an inter-packet delay variation of the network segment based on the transmission timestamp and the reception timestamp of two or more synthetic packets, and

derive an available bandwidth of the network segment based on the calculated inter-packet delay variation.

10 . The system of claim 9 in which said second processor is adapted to use said derived available bandwidthto trigger one or more actions.

11 . The system of claim 10 wherein said one or more actions comprises changing the configuration of traffic shapers for said network segment.

12 . The system of claim 9 in which said second processor is adapted to derive said available bandwidth based at least in part on one or more previously calculated inter packet delay variations.

13 . The system of claim 9 in which said first processor is adapted to generate each of said plurality of synthetic packets with the same predetermined number of bytes.

14 . The system of claim 9 in which said first processor is adapted to transmit said plurality of synthetic packets substantially consecutively.

15 . The system of claim 9 , in which said second processor is adapted to calculate the inter packet delay variation by

calculating a first delay as a difference between the reception timestamp and the transmission timestamp for a first of said plurality of synthetic packets,

calculating a second delay for a second synthetic packet as a difference between the reception timestamp and the transmission timestamp for the second of said plurality of synthetic packets, and

setting the inter packet delay variation as the difference between said second delay and said first delay.

16 . A system according to claim 9 , in which said second processor is adapted to derive an available bandwidth of the network segment by

multiplying a number of bytes in a first synthetic packet by the rate of a first link in said network segment and adding the calculated inter packet delay variation for said first synthetic packet, and

dividing the resulting sum by a number of bytes in said synthetic packet.