The measurement of time synchronization accuracy can be extended to additional testing

A) looking if NTP could provide a good clock for direct OWD measurement
B) see if test tools like NetIQ and IPANEMATECH are accurate enough

ad A)

Besides basic measurement of time synchronization accuracy we can use our boxes for testing of OWD measurement. The OWD is measured directly by sending a packet from box A to box B with timestamp of transmition time. Box B adds its timestamp of reception time and saves both timestamps and packet characteristics. We can use a pair of programs RUDE/CRUDE for this task. Time in A and B is synchronized by NTP. OWD delay measured in this way is influenced by actual offset of clock in A and B. If both A and B are supplied with PPS (which is not used for synchronization), we can know actual offset of the local clock and therefore we can calculate the error of measured OWD between A and B.

In the following text we use this convention:

A,B,C - our measurement boxes
NREN-x - NREN where the measurement box 'x' is located
NTP-x - primary NTP server in NREN-x (might be a RIPE box)
INST-x - institute network connected to NREN-x

Organization of measurement

boxes A and B run NTP clients synchronized with NTP servers
measure the OWD between A and B
optionally: calculate exact OWD between A and B if both are supplied with PPS and we know actual offset of local time
optionally: if PPS is not available but there are RIPE boxes in both NREN's, we can compare measured OWD between A and B with the OWD between RIPE boxes

Three possible setups

1) two primary NTP servers

NTP-A and NTP-B are located in both NREN-A and NREN-B, near A and B
boxes A and B run NTP clients synchronized with their primary NTP servers

2) one primary NTP server

primary server NTP-A is located in NREN-A
boxes A and B run NTP clients synchronized with the same NTP-A server

3) two secondary NTP servers (requires additional boxes)

two primary NTP servers are located in NREN-A and NREN-B
secondary NTP servers in INST-A and INST-B are synchronized with primary NTP servers in their NREN
boxes A and B are located in INST-A and INST-B
boxes A and B run NTP clients synchronized with secondary server in INST-A and INST-B

Then we compare the results of these three tests and determine the influence of NTP synchronization.

ad B)

Tools like NetIQ or IPANEMATECH can be verified by following method

install the tools on boxes Ax and Bx
our boxes A and B are located in the same LAN as Ax and Bx
A and B are provided by PPS, so we can measure exact OWD between A and B
measure OWD with the tool and compare it with OWD between A and B