System Operation As An Ntp Server; Platform Considerations; References - Juniper SYSTEM BASICS - CONFIGURATION GUIDE V 11.1.X Configuration Manual

JUNOSe 11.1.x System Basics Configuration Guide
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System Operation as an NTP Server

The NTP server supports both unicast (user-to-user addressing protocol) and broadcast
modes. Depending on the server configuration you choose, the system functions in
different ways:
If the system is configured both as an NTP client and an NTP server, the system
effectively synchronizes its clients to its master's clock. If the system is configured
as an NTP server but not an NTP client, the system synchronizes its clients to its own
clock, which can be set by the clock commands.
NOTE: When the system is not configured as either an NTP client or an NTP server,
it responds to NTP requests with an invalid stratum number.

Platform Considerations

The system clock is supported on all E Series routers.
For information about the modules supported on E Series routers:

References

This implementation of NTP meets the following specifications:
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Platform Considerations
The system evaluates which server is currently the best time source (the master)
by analyzing time data in the messages and comparing the data from different
servers.
The system gradually synchronizes its clock to that of the master.
When the system is configured as a unicast NTP server, it synchronizes clients
to its own clock by responding to NTP requests from clients as follows:
Swaps the destination and source addresses in the request packet.
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Sets all timestamps and NTP attributes in the packet.
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Returns the packet to the client.
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When the system is configured as a broadcast NTP server, it periodically sends
NTP time synchronization messages to the local network broadcast address
(255.255.255.255). The broadcast server would also respond to any NTP unicast
requests from clients.
See the ERX Module Guide for modules supported on ERX7xx models, ERX14xx
models, and the ERX310 Broadband Services Router.
See the E120 and E320 Module Guide for modules supported on the E120 and
E320 Broadband Services Routers.
RFC 1305 Network Time Protocol (version 3) Specification, Implementation
and Analysis (March 1992)