Multiple Instances Of Ntp; Configuring The Operation Modes Of Ntp - 3Com MSR 50 Series Configuration Manual

Multiple Instances of
Configuring the
Operation Modes of
NTP
to the default NTP multicast address 224.0.1.1, with the Mode field in the
messages set to 5 (multicast mode). Clients listen to the multicast messages from
servers. After a client receives the first multicast message, the client and the server
start to exchange messages, with the Mode field set to 3 (client mode) and 4
(server mode) to calculate the network delay between client and the server. Then,
the client enters the multicast client mode and continues listening to multicast
messages, and synchronizes its local clock based on the received multicast
messages.
The server/client mode and symmetric mode support multiple instances of NTP
NTP and thus support clock synchronization within an MPLS VPN network. Namely,
network devices (CEs and PEs) at different physical location can get their clocks
synchronized through NTP, as long as they are in the same VPN. The specific
functions are as follows:
The NTP client on a customer edge device (CE) can be synchronized to the NTP
■
server on another CE.
The NTP client on a CE can be synchronized to the NTP server on a provider
■
edge device (PE).
The NTP client on a PE can be synchronized to the NTP server on a CE through
■
a designated VPN instance.
The NTP client on a PE can be synchronized to the NTP server on another PE
■
through a designated VPN instance.
The NTP server on a PE can synchronize the NTP clients on multiple CEs in
■
different VPNs.
n
A CE is a device that has an interface directly connecting to the service provider
■
(SP). A CE is not "aware of" the presence of the VPN.
A PE is a device that directly connecting to CEs. In an MPLS network, all events
■
related to VPN processing occur on the PE.
Devices can implement clock synchronization in one of the following modes:
Server/client mode
■
Symmetric mode
■
Broadcast mode
■
Multicast mode
■
For the server/client mode or symmetric mode, you need to configure only clients
or symmetric-active peers; for the broadcast or multicast mode, you need to
configure both servers and clients.
n
A single device can have a maximum of 128 associations at the same time,
including static associations and dynamic associations. A static association refers
to an association that a user has manually created by using an NTP command,
while a dynamic association is a temporary association created by the system
during operation. A dynamic association will be removed if the system fails to
receive messages from it over a specific long time. In the server/client mode, for
example, when you carry out a command to synchronize the time to a server, the
system will create a static association, and the server will just respond passively

Configuring the Operation Modes of NTP

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