Ntp Configuration Task List; Multiple Instances Of Ntp - 3Com 4510G Configuration Manual

Multicast mode
Figure 24-6 Multicast mode
Server
Periodically multicasts clock
synchronization messages (Mode 5)
Clock synchronization message
exchange (Mode 3 and Mode 4)
Periodically multicasts clock
synchronization messages (Mode 5)
In the multicast mode, a server periodically sends clock synchronization messages to the
user-configured multicast address, or, if no multicast address is configured, 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.
In symmetric peers mode, broadcast mode and multicast mode, the client (or the symmetric active
peer) and the server (the symmetric passive peer) can work in the specified NTP working mode only
after they exchange NTP messages with the Mode field being 3 (client mode) and the Mode field being
4 (server mode). During this message exchange process, NTP clock synchronization can be
implemented.

Multiple Instances of NTP

The client/server mode and symmetric mode support multiple instances of NTP and thus support clock
synchronization within more than one VPN network. Namely, network devices at different physical
location can get their clocks synchronized through NTP, as long as they are in the same VPN.

NTP Configuration Task List

Complete the following tasks to configure NTP:
Configuring the Operation Modes of NTP
Configuring Optional Parameters of NTP
Client
Network
After receiving the first
multicast message, the
client sends a request
Calculates the network delay
between client and the server
and enters the multicast
messages and synchronizes
Task
client mode
Receives multicast
its local clock
Required
Optional
24-6
Remarks