D: Network Time Protocol (NTP)
D: Network Time Protocol (NTP)
As an option, Symmetricom can factory configure the XL-GPS to function as a Stratum 1
network time server. Network time servers use Network Time Protocol (NTP) to synchronize
computer clocks across a network. Alternatively, customers can upgrade a XL-GPS unit in
the field by purchasing the NTS option and installing a key to enable it.
Support for version 4.0 of the NTP, RFC 1305 as well as the Simple Network Time Protocol
(SNTP), RFC2030 is available. In addition, the XL-GPS responds to TIME protocol
requests, RFC868.
The Network Time Server responds to time synchronization requests from hosts using these
User Datagram Protocol/Internet Protocols (UDP/IP):
Type/Protocol Port Number RFC
NTP ver. 4.0: UDP Port 123 RFC1305
SNTP: UDP Port 123 RFC2030
TIME: UDP Port 37 RFC868
NTP Packet Transmitted Timestamp Accuracy ±10 milliseconds.
Editing ntp.conf
Note: The XL-GPS is a Stratum 1 NTP server. Therefore, it does not support NTP peering,
in which a time server gets time information by sending an NTP query to another time
server. Entering valid IP addresses for the ‘server’ parameters (e.g., “server
216.210.169.40”) in ntp.conf does not enable peering in the XL-GPS.
The current text of “ntp.conf” is as follows:
# X L - G P S N T P . C O N F
# Load this version into the XL-GPS NTP Server for NTP MD5 and NTP
broadcast
#
# The line below to enables NTP broadcast mode using MD5 key 1.
broadcast 192.168.47.255 key 1
# Trust and accept NTP packets using MD5 keys 1 or 2.
# The MD5 keys and key ID specified in the XL-GPS's NTP.KEYS file must
match the
# same ones in the UNIX/Linux client NTP.KEYS file. The same keys for
both
# units must be specified as trusted by the line below.
trustedkey 1 2
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