Microsemi SyncServer S200 User Manual page 37

In the following explanations, the term "SyncServer" means "the local NTP daemon on the
SyncServer".
Role
Server:
n
Addressing: Use with IPv4 class A, B and C addresses.
n
Description: Creates a persistent association between the SyncServer (client)
n
and an NTP node (server). The client synchronizes with the server if the client's
clock selection algorithm selects this server as the best clock. Typical server asso-
ciations include: the hardware clock, the factory default NTP servers, and servers
added by the user. Also see system peer mode: client under NTP Daemon
Status.
Typical Usage: The user creates a Server association to designate an NTP node
n
that has an NTP Stratum better or equal to that of the SyncServer (client). Often,
the NTP server is another Stratum 1 server with a GPS reference that is outside
the user's administrative jurisdiction. The NTP servers operated by Microsemi
that are part of the factory default configuration are an example of this.
Peer:
n
Addressing: Use with IPv4 class A, B and C addresses.
n
Description: Creates a persistent symmetric-active association between the Syn-
n
cServer (peer1) with an NTP node (peer2). For the NTP node running in sym-
metric passive mode, there is nothing needs to be done on the NTP node.
However, the NTP node can be configured in symmetric active mode too. When
configured, the two nodes can synchronize with each other in a variety of failure
scenarios, such as loss of GPS and Internet connectivity. See system peer mode:
symmetric-active under NTP Daemon Status.
Typical Usage: The user configures NTP associations on two NTP nodes that
n
point to the each other. The two nodes are usually of equal stratum and have inde-
pendent references, such as two separate GPS installations or two separate net-
work paths to NTP servers on the Internet. In the event of a reference failure, the
peers can synchronize to the node that has the best remaining reference.
Broadcast:
n
Addressing: Use an IPv4 broadcast address of the local subnet. To broadcast
n
NTP messages on a subnet, if the local interface IP address were 192.168.61.58
and the mask were 255.255.255.0, the broadcast address could be
192.168.61.255.
Description: Creates a broadcast server association. When configured with a
n
broadcast address (e.g., 192.168.61.255), the association broadcasts NTP mes-
sages from the network interface with the matching IP address (e.g.,
192.168.61.58). Broadcast messages go out to all nodes on the subnet, and are
usually blocked by routers from reaching adjacent subnets. Consult with the net-
work administrator to select a correctly-scoped address and Time to live value.
This type of association requires authentication on both the server and the clients.
n
See Using NTP Authentication.
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