One-way packet delay measurement
A method for measuring one-way delays in a communications network, the method comprising: maintaining, at a third node having a reference clock, a first virtual clock state emulating a first node clock located at a first node and a second virtual clock state emulating a second node clock located at a second node; registering a timeset comprising transmission and reception times at the first node and the second node, respectively, for each packet of a plurality of packets that are transmitted from the first node to the second node and reflected from the second node back to the first node; converting times in the timeset, responsive to the first and/or second virtual clocks, into times in accordance with the reference clock; calculating, for each packet of the plurality of packets, a forward one-way delay (FOWD) and a reverse one-way delay (ROWD), responsive to the converted timeset.
1. A method for measuring one-way delays in a communications network, the method comprising:
maintaining, at a third node having a reference clock, a first virtual clock state emulating a first node clock located at a first node and a second virtual clock state emulating a second node clock located at a second node;
registering a timeset comprising transmission and reception times at the first node and the second node, respectively, for each packet of a plurality of packets that are transmitted from the first node to the second node and reflected from the second node back to the first node;
converting times in the timeset, responsive to the first and/or second virtual clocks, into times in accordance with the reference clock;
calculating, for each packet of the plurality of packets, a forward one-way delay (FOWD) from the first node to the second node and a reverse one-way delay (ROWD) from the second node to the first node, responsive to the converted timeset.
2. The method according to claim 1 , further comprising computing at least one one-way delay statistic for the FOWD and/or the ROWD, the at least one one-way delay statistic being selected from the group consisting of: a minimum, a maximum, a standard deviation, a skew, a kurtosis, and a percentile histogram.
3. The method according to claim 1 , wherein the delay analysis engine is further operable to determine an estimated forward floor delay (FFD) and an estimated reverse floor delay (RFD) responsive to the FOWD and the ROWD, respectively.
4. The method according to claim 3 , the delay analysis engine is further operable to update a state of the at least one virtual clock responsive to the estimated FFD and/or the RFD.
5. The method according to claim 1 , wherein the communications session is a conventional DM session and the second node is a standard reflector node conventionally used to determine round-trip time.
6. The method according to claim 1 , wherein the communications session is a single communications session.
7. An apparatus for measuring one-way delays in a communications network, the apparatus comprising:
a first virtual clock emulating a first node clock located in a remote first node and a second virtual clock emulating a second node clock located in a remote second node;
a reference clock;
a delay analysis engine operable to:
register, for each packet of a plurality of packets that are transmitted from the first node to the second node and reflected from the second node back to the first node, a timeset comprising transmission and reception times at the first node and the second node, respectively;
convert times in the timeset, responsive to the first and/or second virtual clocks, into times in accordance with the reference clock;
calculate, for each packet of the plurality of packets, a forward one-way delay (FOWD) from the first node to the second node and a reverse one-way delay (ROWD) from the second node to the first node, responsive to the converted timeset.
8. The apparatus according to claim 7 , further comprising computing at least one one-way delay statistic for the FOWD and/or the ROWD, the at least one one-way delay statistic being selected from the group consisting of: a minimum, a maximum, a standard deviation, a skew, a kurtosis, and a percentile histogram.
9. The apparatus according to claim 7 , wherein the delay analysis engine is further operable to determine an estimated forward floor delay (FFD) and an estimated reverse floor delay (RFD) responsive to the FOWD and the ROWD, respectively.
10. The apparatus according to claim 9 , the delay analysis engine is further operable to update a state of the first virtual clock and/or the second virtual clock responsive to the estimated FFD and/or the RFD.
11. The apparatus according to claim 7 , wherein the communications session is a conventional DM session and the second node is a standard reflector node conventionally used to determine round-trip time.
12. The apparatus according to claim 7 , wherein the communications session is a single communications session.