20250110 - Andrew Gallo/GWU - “PTP perfSONAR - New Friends?”

Authors:
Andrew Gallo - GWU
Date:
January 10th, 2025
Title:
PTP perfSONAR - New Friends?
Abstract:
perfSONAR is widely deployed as a performance testing and monitoring tool in many networks in our community. Seeing the value in wide area monitoring, some operators have used these tools for intra-campus or metropolitan network monitoring. One of the key tests run by perfSONAR is one-way latency (via one-way active measurement protocol - OWAMP). The challenge of one-way latency measurement is that it involves two clocks, one on the sending node and one on the receiving node. These clocks need to be synchronized to a high level of precision (and hopefully accuracy). Some operators have reported seeing negative latencies between nodes that are close to each other.
We can trace these impossible results to node clocks that are not synchronized to a high enough level of precision to measure low latency paths. When nodes are close enough such that the one-way latencies are within the error tolerance of the Network Time Protocol (NTP, the most common node synchronization method), then OWAMP results will not be reliable.
This talk presents the use of the Precision Time Protocol (PTP, also known as IEEE 1588) as a better alternative to NTP for this use-case.