Web Interface
association initiates a brief exchange with the server to calibrate the propagation
delay. Afterwards, the multicast client association listens to and gets the time from
the server messages. This type of association requires authentication on both the
server and the clients. See Using NTP Authentication (on page 160).
n Typical Usage: Multicast client associations can get authenticated time on net-
works that have a multicast server.
Note: When authentication is configured, the same authentication scheme is available for all
NTP associations and over all network interfaces.
Prefer: The NTP daemon will synchronize with an association marked prefer over an equi-
valent association that is not.
Address: The IP address or DNS name of the NTP association.
(If present, configure the Modem phone number using the REFERENCES - Modem page.)
Port: (Factory Default = "Default") With the default setting, the NTP daemon automatically
detects and uses a valid network port to communicate with configured NTP server(s).
Depending on the IP routing infrastructure, this is typically LAN1. The user can override this
by selecting a specific network port. If so, the address must be specified using an IP address
instead of a DNS name. The Port setting is only available for Server, Peer, Broadcast, and
Multicast associations.
Burst
n
Burst: When the server is reachable, send a burst of eight packets instead of the usual
one. The packet spacing is about two seconds. This is designed to improve timekeeping
quality for server associations. This setting should only be used in agreement with the
administrator of the remote NTP device as the traffic load may be onerous.
n
iBurst: When the server is unreachable, send a burst of eight packets instead of the usual
one. As long as the server is unreachable, the packet spacing is about 16s to allow a
modem call to complete. Once the server is reachable, the packet spacing is about two
seconds. This is designed to speed the initial synchronization acquisition with the server
command.
Version: Specifies the version number to be used for outgoing NTP packets. Versions 1-4 are
the choices, with version 4 the default.
Minimum / Maximum Poll Interval: These options specify the minimum and maximum poll inter-
vals for NTP messages, in seconds to the power of two. The maximum poll interval defaults
to 10 (1,024 s), but can be increased to an upper limit of 17 (36.4 h). The minimum poll inter-
val defaults to 6 (64 s), but can be decreased to a lower limit of 4 (16 s).
MD5 Key: Use this field to authenticate NTP messages to and from the SyncServer for this
specific association. When enabled, the NTP packet header includes authentication fields
encrypted using either the MD5 key number (1 to 16) or autokey. Prior to selecting either
option, the user must configure the NTP - MD5 Keys, NTP - Autokey, or NTP - Autokey Client
pages.
Note: MD5 and Autokey cannot be used on the SyncServer concurrently. Configuring one
method erases the keys or certificates of the other.
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