Comtech EF Data CDM-425, Installation And Operation Manual

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CDM-425 Advanced Satellite Modem
Revision 0
Appendix I I–16 MN-CDM-425
I.7 Advanced Network Timing
I.7.1 Overview
The Advanced Network Timing (ANT) feature provides IP-based protocols to synchronize the
modem's internal time-of-day clock to an external device such as a time server, Base Station
Controller (BSC), or Radio Network Controller (RNC).
I.7.2 SNTP (Simple Network Time Protocol)
The Simple Network Time Protocol (SNTP), defined in RFC-1361, provides millisecond-resolution
time synchronization with a time server. When the modem synchronizes its time, it also
synchronizes the time of all connected EDMAC devices, such as slave LPODs or CSATs. When
all devices are synchronized, administrators can better correlate logged events between devices.
SNTP is a User Datagram Protocol (UDP) that works on port 123. If the modem is not updating its
time, verify that there are no network devices between the modem and time server that might
block UDP packets on that port.
I.7.3 Precision Time Protocol (PTP)
For better PTP clock accuracy, ingress and egress port sync interval should be
at least two seconds.
Figure I-13. Point-to-Point Network with PTP Configuration Example