H3C S5600 series Operation Manual

Also see for H3C S5600 Series: Configuration Operation manual Operation manual Operation manual Operation manual

Contents

H3C S5600 series Operation Manual Manual pdf 4 page image

Operation Manual – NTPH3C S5600 Series Ethernet Switches-Release 1510 Chapter 1 NTP Configuration1-3The procedures of synchronizing system clocks are as follows:z LS_A sends an NTP packet to LS_B, with the timestamp identifying the time whenit is sent (that is, 10:00:00am, noted as T1) carried.z When the packet arrives at LS_B, LS_B inserts its own timestamp, which identifies11:00:01am (noted as T2) into the packet.z Before this NTP packet leaves LS_B, LS_B inserts its own timestamp once again,which identifies 11:00:02am (noted as T3).z When receiving the response packet, LS_A inserts a new timestamp, whichidentifies 10:00:03am (noted as T4), into it.At this time, LS_A has enough information to calculate the following two parameters:z The delay for an NTP packet to make a round trip between LS_A and LS_B: delay= (T4 -T1)-(T3 -T2).z The time offset of LS_A with regard to LS_B: offset = ((T2 -T1) + (T3 -T4))/2.LS_A can then set its own clock according to the above information to synchronize itsclock to that of LS_B.For the detailed information, refer to RFC1305.1.1.3 NTP Implementation ModeTo accommodate networks of different structures and switches in different networkpositions, NTP can operate in multiple modes, as described in the following.I. Client/Server modeNetw orkClient ServerClock synchronizationrequest packetResponse packetFilter and select clocksand synchronize itsow n clock to that ofthe selected serverNetw orkClientWork as a serverautomatically andsend responsepacketsServerResponse packetFilter and select clocksand synchronize itsow n clock to that ofthe selected serverNetw orkClientWork as a serverautomatically andsend responsepacketsServerClock synchronizationrequest packetResponse packetFilter and select clocksand synchronize itsow n clock to that ofthe selected serverNetw orkClientWork as a serverautomatically andsend responsepacketsServerResponse packetFilter and select clocksand synchronize itsow n clock to that ofthe selected serverWork as a serverautomatically andsend responsepacketseFigure 1-2 NTP implementation mode: client/Sever mod