Method for analyzing network trace, method for judging order among nodes, processor for analyzing network trace, computer-executable program for controlling computer as processor, and method for correcting time difference among nodes in network
View Patent ↗A processor and program for analyzing network trace with the use of data packets transmitted via a network includes: a memory section 32 for storing trace data generated from the data packets; a packet analyzing section 34 for retrieving a pair of packets belonging to the same session from the trace data to generate an order relation between nodes; an array data generating section 36 for using packet pair data and order relation data to generate and store array data used for estimating time difference of the specific time axis of each node; and a solution engine section 38 for calculating an estimated value of the time difference with the use of the array data to store the estimated value in a memory.
1. A time difference correction method for correcting time difference of specific time axes of nodes connected to a computer network, the method comprising:
acquiring trace data at each node by analyzing time stamps of data packets transmitted via the computer network;
determining from the trace data an order relation along a transaction direction among the nodes;
generating a range of time difference of the specific time axes based on numerical analysis involving data with respect to the order relation, the generation step comprising creating array data for the purpose of representing and solving simultaneous linear inequalities; and
selecting a time correction value from within the range of time difference.
2. The method according to claim 1 , wherein time difference is included in the array data as a variable.
3. The method according to claim 1 , wherein determining the order relation comprises determining which is the larger of differences between time stamps given when a pair of packets retrieved from the trace data and belonging to the same session pass two adjoining nodes.
4. The method according to claim 1 , wherein determining the order relation comprises:
reading the trace data;
retrieving from the trace data a pair of packets belonging to the same session;
reading time stamps given when the pair of packets pass each of a plurality of predetermined nodes;
calculating a time stamp difference at each of the plurality of predetermined nodes based on the time stamps given at each of the plurality of predetermined nodes; and
comparing the calculated time stamp differences.
5. The method according to claim 4 , wherein determining the order relation further comprises assigning a node at which the time stamp difference is larger on the upstream of the transaction direction and a node at which the time stamp difference is smaller on the downstream of the transaction direction.
6. A time difference correction method for correcting time difference of specific time axes of nodes connected to a computer network, the method comprising:
acquiring trace data at each node by analyzing time stamps of data packets transmitted via the computer network;
determining from the trace data an order relation along a transaction direction among the nodes;
generating simultaneous inequalities via the order relation;
solving the simultaneous inequalities in order to obtain a range of time difference of the specific time axes; and
selecting a time correction value from within the range of time difference.
7. The method according to claim 6 , further comprising storing the simultaneous inequalities in memory in an array data format.
8. The method according to claim 6 , wherein determining the order relation comprises determining which is the larger of differences between time stamps given when a pair of packets retrieved from the trace data and belonging to the same session pass two adjoining nodes.
9. The method according to claim 6 , wherein determining the order relation comprises:
reading the trace data;
retrieving from the trace data a pair of packets belonging to the same session;
reading time stamps given when the pair of packets pass each of a plurality of predetermined nodes;
calculating a time stamp difference at each of the plurality of predetermined nodes based on the time stamps given at each of the plurality of predetermined nodes; and
comparing the calculated time stamp differences.
10. The method according to claim 9 , wherein determining the order relation further comprises assigning a node at which the time stamp difference is larger on the upstream of the transaction direction and a node at which the time stamp difference is smaller on the downstream of the transaction direction.