Huawei Quidway S5600 Series Operation Manual page 832

Operation Manual – NTP
Quidway S5600 Series Ethernet Switches-Release 1510
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Figure 1-1 Working principle of NTP
The procedures of synchronizing system clocks are as follows:
LS_A sends an NTP packet to LS_B, with the timestamp identifying the time
when it is sent (that is, 10:00:00am, noted as T
When the packet arrives at LS_B, LS_B inserts its own timestamp, which
identifies 11:00:01am (noted as T
Before this NTP packet leaves LS_B, LS_B inserts its own timestamp once again,
which identifies 11:00:02am (noted as T
When receiving the response packet, LS_A inserts a new timestamp, which
identifies 10:00:03am (noted as T
At this time, LS_A has enough information to calculate the following two parameters:
The delay for an NTP packet to make a round trip between LS_A and LS_B:
delay = (T
The time offset of LS_A with regard to LS_B: offset = ((T
LS_A can then set its own clock according to the above information to synchronize its
clock to that of LS_B.
For the detailed information, refer to RFC1305.
NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet 10:00:00 am 10:00:00 am 10:00:00 am 10:00:00 am
10:00:00am 10:00:00am 10:00:00am 10:00:00am
Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork
LS_A LS_A LS_A LS_A LS_A LS_A LS_A LS_A
NTP Packet 10:00:00 am NTP Packet 10:00:00 am
Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork
LS_A LS_A LS_A LS_A LS_A LS_A LS_A LS_A
NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet NTP Packet 10:00:00 am 11:00:01 am 11:00:02 am 10:00:00 am 11:00:01 am 11:00:02 am 10:00:00am 10:00:00am 10:00:00 am 11:00:01 am 10:00:00 am 11:00:01 am 10:00:00am 10:00:00am
Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork
LS_A LS_A LS_A LS_A LS_A LS_A LS_A LS_A
NTP Packet received at 10:00:03 am NTP Packet received at 10:00:03 NTP Packet received at 10:00:03 am NTP Packet received at 10:00:03 NTP Packet received at 10:00:03 NTP Packet received at 10:00:03 am NTP Packet received at 10:00:03 NTP Packet received at 10:00:03 am
Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork Netw ork
LS_A LS_A LS_A LS_A LS_A LS_A LS_A LS_A
-T )-(T -T ).
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Huawei Technologies Proprietary
LS_B LS_B LS_B LS_B LS_B LS_B
LS_B LS_B
NTP Packet10:00:00am NTP Packet10:00:00 am NTP Packet10:00:00am NTP Packet10:00:00am NTP Packet10:00:00am NTP Packet10:00:00 am 11:00:01 am 11:00:01 am 11:00:01am 11:00:01 am 11:00:01am 11:00:01am 11:00:01 am 11:00:01am
LS_B LS_B LS_B LS_B LS_B LS_B LS_B LS_B
11:00:01am 11:00:01am 11:00:01am 11:00:01am 11:00:02am 11:00:02am 11:00:02 am 11:00:02am 11:00:02am 11:00:02 am
LS_B LS_B
LS_B LS_B LS_B LS_B LS_B LS_B
LS_B LS_B LS_B LS_B LS_B LS_B LS_B LS_B
) carried.
1
) into the packet.
2
).
3
), into it.
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Chapter 1 NTP Configuration
-T ) + (T -T ))/2.
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