Basic System Configuration Guide System Management
Edition: 01 3HE 11010 AAAC TQZZA 201
6.1.2.3 SNTP Time Synchronization
For synchronizing the system clock with outside time sources, the 7705 SAR
includes a Simple Network Time Protocol (SNTP) client. As defined in RFC 2030,
SNTP Version 4 is an adaptation of the Network Time Protocol (NTP). SNTP typically
provides time accuracy within 100 ms of the time source. SNTP can only receive the
time from NTP servers; it cannot be used to provide time services to other systems.
SNTP is a compact, client-only version of NTP. SNTP does not authenticate traffic.
SNTP can be configured in both unicast client modes (point-to-point) and broadcast
client modes (point-to-multipoint). SNTP should be used only at the extremities of the
synchronization subnet. SNTP clients should operate only at the highest stratum
(leaves) of the subnet and in configurations where no NTP or SNTP client is
dependent on another SNTP client for synchronization. SNTP time servers should
operate only at the root (Stratum 1) of the subnet and then only in configurations
where no other source of synchronization other than a reliable radio clock is
available.
The 7705 SAR SNTP client can be configured for either broadcast or unicast client
mode.
6.1.2.4 PTP
Precision Time Protocol (PTP) is a timing-over-packet protocol defined in the IEEE
1588v2 standard 1588 2008.
PTP provides the capability to synchronize network elements to a Stratum-1 clock or
primary reference clock (PRC) traceable source over a network that may or may not
be PTP-aware. PTP has several advantages over ACR. It is a standards-based
protocol, has lower bandwidth requirements, can transport both frequency and time,
and can potentially provide better performance.
For more information about PTP, see IEEE 1588v2 PTP.
6.1.2.5 Time-of-Day Measurement (ToD-1pps)
The 7705 SAR can receive and extract time of day/phase recovery from a 1588
grand master clock or boundary clock and transmit the recovered time of day/phase
signal to an external device such as a base station through an external time of day
port, where available. Transmission is through the ToD or ToD/PPS Out port with a
1 pulse/s output signal. The port interface communicates the exact time of day by the
rising edge of the 1 pulse/s signal.
To Next Page
Loading...
