Method and apparatus for one-way passive loss measurements using sampled flow statistics

A method for estimating one-way packet loss in a packet network, the method comprising:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• ,
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1,t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• setting the flow start time in each record to the arrival time of a SYN packet;
• setting the flow end time in each record to the arrival time of a FIN packet;
• if the flow start time is within the measurement interval (t1, t2), then attributing the SYN packet to the packet count for the network element that generated the record;
• and
• if the flow end time is within the measurement interval (t1, t2), then attributing the FIN packet to the packet count for the network element that generated the record.

A method for estimating one-way packet loss in a packet network, the method comprising:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1, t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• for the flow (F), setting RF1 as a set of records generated by the flow F at the first network element R1 and RF2 as a set of records generated by the flow F at the second network element R2;
• for all flow records R εRF1 ∪RF2, where the starting time ts and end time te recorded in R either fall within the measurement interval t1 <ts <te <t2, or outside the interval ts <te <t1 or t2 <ts <te;
• calculating the sampled packet counts X1 and X2 as the sum of SYN packets, FIN packets and a total number of packets reported in the flow records which fall entirely within the measurement interval (t1, t2).

A method for estimating one-way packet loss in a packet network, the method comprising:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1, t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• denoting tRs as the flow start time recorded in a record R and tRe as the flow end time recorded in a record R;
• setting the duration of the record dR =tRe −tR s, and the duration of overlap of (tRs,tRe) and the measurement interval (t1, t2) =oR, then:
• X
• 1
• =
• ∑
• R
• ∈
• R
• 1
• ⁢
• ⁢
• o
• R
• d
• R
• ⁢
• n
• R
• ,
• X
• 2
• =
• ∑
• R
• ∈
• R
• 2
• ⁢
• ⁢
• o
• R
• d
• R
• ⁢
• n
• R
• where R1 is the record generated at the first network element, R2 is the record generated at the second network element, and nR is the number of packets reported in record R.

A machine-readable medium containing computer encoded instructions which, when executed by a processor, cause a device to at least:

• receive a first record of sampled packets for a flow from a first network element;
• receive a second record of sampled packets for the flow from a second network element in communication with the first network element;
• determine, for a measurement interval, a first count of the sampled packets in the first record received from the first network element and a second count of the sampled packets in the second record received from the second network element, the first and second counts to account for the sampled packets in the first and second records having been determined by sampling a fraction of packets in a packet stream for the flow;
• and
• estimate packet loss using the first and second counts of the sampled packets for the measurement interval.

A machine-readable medium containing computer encoded instructions which, when executed by a processor, enable a device to estimate one-way packet loss in a packet network by at least:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1, t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• setting the flow start time in each record to the arrival time of a SYN packet;
• setting the flow end time in each record to the arrival time of a FIN packet;
• if the flow start time is within the measurement interval (t1, t2), then attributing the SYN packet to the packet count for the network element that generated the record;
• and
• if the flow end time is within the measurement interval (t1, t2), then attributing the FIN packet to the packet count for the network element that generated the record.

A machine-readable medium containing computer encoded instructions which, when executed by a processor, enable a device to estimate one-way packet loss in a packet network by at least:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1, t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• for the flow (F), setting RF1 as a set of records generated by the flow F at the first network element R1 and RF2 as a set of records generated by the flow F at the second network element R2;
• for all flow records R εRF1 ∪RF2, where the starting time ts and end time te recorded in R either fall within the measurement interval t1 <ts <te <t2, or outside the interval ts <te <t1 or t2 <ts <te;
• calculating the sampled packet counts X1 and X2 as the sum of SYN packets, FIN packets and a total number of packets reported in the flow records which fall entirely within the measurement interval (t1, t2).

A machine-readable medium containing computer encoded instructions which, when executed by a processor, enable a device to estimate one-way packet loss in a packet network by at least:

• receiving a first record of sampled packets for a flow from a first network element;
• receiving a second record of sampled packets for the flow from a second network element communicating with the first network element;
• associating sampled packets from the flow at the first and second network elements with a measurement interval;
• and
• estimating packet loss using a count of the sampled packets associated with the measurement interval, wherein the estimated packet loss is represented by:
• p
• ^
• =
• 1
• -
• X
• 2
• /
• s
• X
• 1
• /
• s
• =
• 1
• -
• X
• 2
• X
• 1
• wherein, X1 and X2 equal the count of sampled packets from the first and second network elements, respectively, with a packet sampling rate s during the measurement interval defined as (t1, t2), and wherein associating sampled packets from the flow with the measurement interval (t1, t2) comprises:
• denoting tRs as the flow start time recorded in a record R and tRe as the flow end time recorded in a record R;
• setting the duration of the record dR =tRe −tR s, and the duration of overlap of (tRs, tRe) and the measurement interval (t1, t2) =oR, then:
• X
• 1
• =
• ∑
• R
• ∈
• R
• 1
• ⁢
• ⁢
• o
• R
• d
• R
• ⁢
• n
• R
• ,
• X
• 2
• =
• ∑
• R
• ∈
• R
• 2
• ⁢
• ⁢
• o
• R
• d
• R
• ⁢
• n
• R
• where R1 is the record generated at the first network element, R2 is the record generated at the second network element, and nR is the number of packets reported in record R.