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Table 10 NTP/SNTP operating modes
Mode
Operating process
Principle
Application scenario
Client/server
1.
A client sends a clock
synchronization message to
the NTP servers.
2.
Upon receiving the
message, the servers
automatically operate in
server mode and send a
reply.
3.
If the client is synchronized
to multiple time servers, it
selects an optimal clock and
synchronizes its local clock
to the optimal reference
source.
You can configure multiple time
servers for a client.
This operating mode requires
that you specify the IP address of
the NTP server on the client.
A client can synchronize
to a server, but a server
cannot synchronize to a
client.
This mode is intended for
scenarios where devices
of a higher stratum
synchronize to devices
with a lower stratum.
Symmetric
active/passive
1.
A symmetric active peer
periodically sends clock
synchronization messages
to a symmetric passive
peer.
2.
The symmetric passive peer
automatically operates in
symmetric passive mode
and sends a reply.
3.
If the symmetric active peer
can be synchronized to
multiple time servers, it
selects an optimal clock and
synchronizes its local clock
to the optimal reference
source.
You must specify the IP address
of the symmetric passive peer on
the symmetric active peer.
A symmetric active peer
and a symmetric
passive peer can be
synchronized to each
other. If both of them are
synchronized, the peer
with a higher stratum is
synchronized to the
peer with a lower
stratum.
This mode is most often
used between servers
with the same stratum to
operate as a backup for
one another. If a server
fails to communicate with
all the servers of a lower
stratum, the server can
still synchronize to the
servers of the same
stratum.
NTP/SNTP time source authentication
The time source authentication function enables the device to authenticate the received NTP or
SNTP packets. This feature ensures that the device obtains the correct GMT.
Administrators
An administrator configures and manages the device from the following aspects:
•
User account management
—Manages user account information and attributes (for example,
username and password).
•
Role-based access control
—Manages user access permissions by user role.
•
Password
control
—Manages user passwords and controls user login status based on
predefined policies.
