Method, a computer program product, and a carrier for indicating one-way latency in a data network
Disclosed herein is a method, a computer program product, and a carrier for indicating one-way latency in a data network (N) between a first node (A) and a second node (B), wherein the data network (N) lacks continuous clock synchronization, comprising: a pre-synchronization step. A measuring step, a post-synchronisation step, an interpolation step, and generating a latency profile. The present invention also relates to a computer program product incorporating the method, a carrier comprising the computer program product, and a method for indicating server functionality based on the first aspect.
1. A system to determine a one-way latency between a first node and a second node in a network, comprising:
a plurality of first sync messages comprising a first timestamp transmitted from the first node at a first time to the second node;
a second sync message sent by said second node in response to receiving said first sync message at a second time, said second sync message comprising, said first timestamp, a second timestamp representing said second time and a third timestamp representing a third time at which said second sync message is transmitted from the second node to the first node;
one or more sync values calculated upon reception of said second sync message at said first node at a fourth time, said sync values calculated based on said first timestamp, said second timestamp, said third timestamp and said fourth time;
a plurality of measurement messages comprising a fifth time stamp representing a fifth time at which said measurement message is sent from the first to the second node;
a memory for storing said fifth timestamp upon reception of said measurement message at said second node and for storing a sixth time at which said measurement message is received at said second node; and
a one-way latency profile calculated based on a combination of the fifth and sixth timestamps and the one or more sync values.
2. The system of claim 1 further comprising:
a first clock, wherein the first clock determines the first time, the fourth time and the fifth time; and
a second clock, wherein the second clock determines the second time, the fourth time and the sixth time.
3. The system of claim 2 wherein the first clock and the second clock are not synchronized.
4. A method for determining a one-way latency between a first and a second nodes in a network, the method comprising:
sending from the first node a plurality of first sync messages comprising a first timestamp representing a first time at which said first sync message is transmitted from the first node to the second node;
sending from the second node a second sync message in response to receiving said first sync message at a second time, said second sync message comprising, said first timestamp, a second timestamp representing said second time and a third timestamp representing a third time at which said second sync message is transmitted from the second node to the first node;
calculating one or more sync values upon reception of said second sync message at said first node at a fourth time, said sync values calculated based on said first timestamp, said second timestamp, said third timestamp and said fourth time;
sending from said first node a plurality of measurement messages comprising a fifth time stamp representing a fifth time at which said measurement message is sent from the first to the second node;
storing said fifth timestamp upon reception of said measurement message at said second node and storing a sixth time at which said measurement message is received at said second node; and
calculating a one-way latency profile based on a combination of the fifth and sixth timestamps and the one or more sync values.
5. The method of claim 4 further comprising:
determining the first value and the second value using a first clock; and
determining the third value and the fourth value using a second clock.
6. The method of claim 4 wherein the first clock and the second clock are not synchronized.