Association Modes - HPE FlexNetwork 5510 HI Series Network Management And Monitoring Configuration Manual

If the devices in a network cannot synchronize to an authoritative time source, you can select a
device that has a relatively accurate clock from the network, and use the local clock of the device as
the reference clock to synchronize other devices in the network.

Association modes

NTP supports the following association modes:
•
Client/server mode
•
Symmetric active/passive mode
•
Broadcast mode
•
Multicast mode
Table 1 NTP association modes
Mode
Client/server
Symmetric
active/passive
Broadcast
Working process
On the client, specify the IP
address of the NTP server.
A client sends a
synchronization message to the
NTP servers. Upon receiving the
message, the
automatically operate in server
mode and send a reply.
If the client can be synchronized
to multiple time servers, it selects
an optimal clock
synchronizes its local clock to the
optimal reference source after
receiving the replies from the
servers.
On the symmetric active peer,
specify the IP address of the
symmetric passive peer.
A symmetric active
periodically sends
synchronization messages to a
symmetric passive peer. The
symmetric passive
automatically operates
symmetric passive mode and
sends a reply.
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 after receiving the replies
from the servers.
A server periodically sends clock
synchronization messages to the
broadcast
255.255.255.255. Clients listen
to the broadcast messages from
the servers to synchronize to the
server according to
broadcast messages.
When a client receives the first
Principle
clock
servers A client
synchronized
server, but a server
cannot be synchronized
to a client.
and
peer
clock A symmetric active peer
and a
passive peer can be
peer synchronized to each
in other. If both of them are
synchronized, the peer
with a higher stratum is
synchronized
peer with
stratum.
A broadcast client can
address
be synchronized to a
broadcast server, but a
broadcast server cannot
be synchronized to a
the
broadcast client.
9
Application scenario
As Figure 6
can be mode is
to a configurations
devices of
stratum are synchronized
to devices with a lower
stratum.
As Figure 6
mode is most often used
between two or more
symmetric
servers with the same
stratum to operate as a
backup for one another. If
a server
communicate with all the
servers of
to the
stratum, the server can be
a lower
synchronized
servers of
stratum.
A broadcast server sends
clock synchronization
messages to synchronize
clients in
subnet. As
shows, broadcast mode is
intended
configurations
one or a few servers and a
potentially
shows, this
intended for
where
a higher
shows, this
fails to
a higher
to the
the same
the same
Figure 6
for
involving
large client