US 11,711,283 B2
Cable latency measurement
Alan Lo, Boulder, CO (US); Matty Kadosh, Hadera (IL); Marian Pritsak, Issaquah, WA (US); and Yonatan Piasetsky, Tel Aviv (IL)
Assigned to MELLANOX TECHNOLOGIES, LTD., Yokneam (IL)
Filed by MELLANOX TECHNOLOGIES TLV LTD., Raanana (IL)
Filed on Mar. 11, 2021, as Appl. No. 17/198,298.
Prior Publication US 2022/0294717 A1, Sep. 15, 2022
Int. Cl. H04L 43/0864 (2022.01); H04W 24/08 (2009.01); H04L 43/106 (2022.01)
CPC H04L 43/0864 (2013.01) [H04L 43/106 (2013.01); H04W 24/08 (2013.01)] 4 Claims
OG exemplary drawing
 
1. A system comprising:
a first data communication device to generate a data packet, and including:
packet processing circuitry to egress mirror the data packet yielding a probe packet including an egress timestamp TS1; and
a network interface to send the data packet and the probe packet via at least one network connection to a second data communication device, the at least one network connection being at least one cable; and
the second data communication device, an internal latency of data packets in the second data communication device being dynamic, the second data communication device including packet processing circuitry to: receive the probe packet; encapsulate the probe packet with an encapsulation header yielding a return packet, the encapsulation header including a source identification of the second data communication device and a destination identification of the first data communication device; compute the internal latency of the probe packet in the second data communication device based on the difference between a time of ingress of the probe packet in the second data communication device and a time of egress of the return packet from the second data communication device to the first communication device computed based on a time difference of an internal clock of the second data communication device; egress mirror the return packet yielding a response packet; record the computed internal latency in the response packet; and send the response packet to the first data communication device, and wherein:
the network interface of the first data communication device is configured to receive from the second data communication device the response packet including: the egress timestamp TS1; and the computed internal latency of the probe packet in the second data communication device;
the packet processing circuitry of the first data communication device is configured to receive the response packet; ingress mirror the response packet with an ingress timestamp TS2 yielding an ingress mirrored packet; and provide the ingress mirrored packet to a network metric processor, the ingress timestamp TS2 indicating a time at which the response packet ingresses the first data communication device; and
the first data communication device includes the network metric processor to compute a data latency in the at least one network connection between the first data communication device and the second data communication device responsively to the ingress mirrored packet based on TS2 less TS1 less the computed internal latency of the probe packet in the second data communication device.