Version 6.6
269
October 2014
Installation & Operation Manual
30. Time and Date Configuration
30.4
NTP Synchronization and Status
The Media Gateway synchronizes with the NTP server and updates the
Operational
State
and
NTP Server Status
attributes accordingly. The
Operational State
attribute
indicates whether communication is established with a specific NTP server, while the
NTP Server Status
attribute indicates the “current status” of the specific NTP server,
as perceived by a local Media Gateway’s NTP client.
To understand the difference between these two attributes, consider the situation,
where two external NTP servers are used to synchronize time and date of the Media
Gateway (as shown on the above figure). When communication is established with
both servers, their
Operational State
attributes will be set to
Enabled
(and they will be
colored
Green
in the EMS GUI). However at any time, only one server will be chosen
as the synchronization source – its
NTP Server Status
will be set to
Synchronized
,
while another server will be used as an alternative candidate for failover; its
NTP
Server Status
will be set to
Candidate
.
Note that due to the nature of the NTP protocol implementation, there may be a
significant lag in the update of the
Operational State
and the
NTP Server Status
attributes. For example, when the NTP server is disconnected from the IP network, it
may take up to 30 minutes until its
Operational State
is changed to
Disabled
(this
delay is introduced to prevent false failure indications in the case of intermittent
network problems). In addition, when the connection with the NTP server is re-
established, it may take up to 1 hour until the NTP Server is chosen as a
synchronization source, and its
NTP Server Status
attribute is updated accordingly.
In addition to the
Operational State
and
NTP Server Status
attributes, additional
status and timestamp attributes are maintained for each external NTP server. See
Table ’NTP Server Status Parameters’ for details. Use these additional attributes (e.g.
last sent and received message timestamps) to analyze the current state of the
communication with a specific NTP server and to determine possible causes for any
malfunction.
Malfunctioning or suspicious NTP server may be temporarily disabled, by changing its
Administrative State
to
Locked
. The Media Gateway will not establish any
communication with locked NTP servers and will not update their
Operational State
or
NTP Server Status
attributes.
Summary of Contents for Mediant 8000
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