Method for recognizing events and synchronizing clocks

A network transfer device for transferring packets and associated messages between a first and a second subnet of a network comprising:

• a transfer device clock;
• a transfer means for transferring packets between the first and the second subnets, wherein each packet has a local transmittal time and an associated message, connecting between the first and the second subnets;
• a first transfer local media access means for observing the packets and associated messages, wherein the local transmittal time of each packet is contained within the corresponding associated message, connecting to the first subnet;
• a first timing packet detector, connecting to the first transfer local media access means, detecting arrivals and departures of the packets, wherein the first timing packet detector detects a timing data packet arriving at the first transfer local media access means and produces a first recognition signal;
• a second transfer local media access means for observing the packets and associated messages, connecting to the second subnet;
• a second timing packet detector, connecting to the second transfer local media access means, detecting arrivals and departures of the packets, wherein the second timing packet detector detects the timing data packet departing from the second transfer local media access means and produces a second recognition signal;
• a transfer device time server, connecting to the transfer device clock and the first and second timing packet detectors, recording a local arrival time and a local departure time for the timing data packet according to the first and second recognition signals;
• and
• computation means, connecting to the transfer device time server, computing a transfer device transit time from local arrival time and local departure time and generating a transit time message containing the transit time.

A network transfer device for transferring packets and associated messages between a first and a second subnet of a network, comprising:

• a transfer device clock;
• a transfer means for transferring packets between the first and the second subnets, connecting between the first and the second subnets;
• a first transfer local media access means for observing the packets and associated messages, wherein the each packet has a local transmittal time, connecting to the first subnet;
• a first transfer device timing packet detector, connecting to the first local media access means, detecting departures of the packets, wherein the local transmittal time of each packet is contained within the corresponding associated message;
• wherein the first transfer device timing packet detector detects the first transfer timing data packet departing from the first transfer local access media means and produces a first transfer recognition signal;
• a second transfer local media access means for observing the packets and associated messages, connecting to the second subnet,
• a second transfer device timing packet detector, connecting to the second local media access means, detecting departures of the packets;
• wherein the second transfer device timing packet detector detects a second transfer timing data packet departing from the second transfer local access means and produces a second transfer recognition signal;
• a transfer device time server, connecting to the transfer device clock, generating packets and associated messages, receiving the first and second transfer recognition signals and recording a local departure time for the first transfer timing data packet and a local departure time for the second transfer timing data packet;
• and
• computation means, connecting to the transfer device time server, for generating a first transfer synchronization message which contains the local departure time for the first transfer timing data packet and a second transfer synchronization message which contains the local departure time for the second transfer timing data packet.