NTP version 4 Release Notes HP-UX 11i v3 (5900-3073, March 2013)

Manycast scheme
Manycast is an automatic server discovery and configuration paradigm new to NTP v4. It is intended
for a client to troll the network neighborhood to find cooperating servers, validate them using
cryptographic means, and evaluate their time values with respect to other servers that might be
lurking in the vicinity. It uses the grab-n'-drop paradigm with an additional feature where active
means are used to grab additional servers whenever the number of associations fall below the
maxclock option of the tos command.
A manycast client is configured using the manycastclient configuration command, which is
similar to the server configuration command. A manycast client sends ordinary client mode messages
with a broadcast address rather than a unicast address. The message is sent only if less than
maxclock associations remain and only at the minimum feasible rate and minimum feasible
time-to-live (TTL) hops. The polling strategy is designed to reduce the volume of broadcast messages
as much as possible and the effects of implosion due to near-simultaneous arrival of manycast
server messages. There can be as many manycast client associations as different addresses, each
one serving as a template for future unicast client/server associations.
A manycast server is configured using the manycastserver command, which listens to the
specified broadcast address for manycast client messages. If a manycast server is in scope of the
current TTL and is itself synchronized to a valid source and operate at a stratum level equal to or
lower than the manycast client, it replies with an ordinary unicast server message.
Server Pool scheme
The Pool scheme is configured using one or more pool commands with DNS names indicating
the pool from which to draw. The pool command can be used more than once; duplicate servers
are detected and discarded. In principle, it is possible to use a configuration file containing a
single line pool pool.ntp.org.
Command options
Several new commands for NTP configuration have been added in NTP v4. For details, see
ntp.conf(4) manpage.
12 What is new in NTP v4 ?