Operation Manual – NTPH3C S7500E Series Ethernet Switches Chapter 1 NTP Configuration1-7the network delay between client and the server. Then, the client enters the broadcastclient mode and continues listening to broadcast messages, and synchronizes its localclock based on the received broadcast messages.IV. Multicast modeNetworkClientServerAfter receiving the firstmulticast message the clientsends a requestClock synchronization messageexchange (Mode 3 and Mode 4)Periodically multicasts clocksynchronization messages (Mode 5)Calculates the network delaybetween client and server andenters the multicast client modePeriodically multicasts clocksynchronization messages (Mode 5)Receives multicast messagesand synchronizes its localclock，Figure 1-6 Multicast modeIn the multicast mode, a server periodically sends clock synchronization messages tothe user-configured multicast address, or, if no multicast address is configured, to thedefault 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 clientreceives the first multicast message, the client and the server start to exchangemessages, with the Mode field set to 3 (client mode) and 4 (server mode) to calculatethe network delay between client and the server. Then, the client enters the multicastclient mode and continues listening to multicast messages, and synchronizes its localclock based on the received multicast messages.1.1.5 Multiple Instances of NTPNote:Support for this feature varies with devices.The server/client mode and symmetric mode support multiple instances of NTP andthus support clock synchronization within an MPLS VPN network. Namely, networkdevices (CEs and PEs) at different physical location can get their clocks synchronizedthrough NTP, as long as they are in the same VPN. The specific functions are asfollows:z The NTP client on a customer edge device (CE) can be synchronized to the NTPserver on another CE.
