Comtech EF Data CDM-625A Installation And Operation Manual page 663

CDM-625A Advanced Satellite Modem
Appendix K
K.7 Advanced Network Timing
K.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).
K.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 UDP protocol 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.
K.7.3 PTP (Precision Time Protocol)
For better PTP clock accuracy, ingress and egress port sync interval should be at
least 2 seconds.
Figure K-13. Configuration Example – Point-to-Point Network with PTP
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MN-CDM625A
Revision 4