Ntp Implementation Mode - H3C S5600 series Operation Manual

Operation Manual – NTP
H3C S5600 Series Ethernet Switches-Release 1510
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.

1.1.3 NTP Implementation Mode

To accommodate networks of different structures and switches in different network
positions, NTP can operate in multiple modes, as described in the following.
I. Client/Server mode
Filter and select clocks Filter and select clocks Filter and select clocks Filter and select clocks
and synchronize its and synchronize its and synchronize its and synchronize its
ow n clock to that of ow n clock to that of ow n clock to that of ow n clock to that of
the selected server the selected server the selected server the selected server
Figure 1-2 NTP implementation mode: client/Sever mod
) into the packet.
2
-T )-(T -T ).
4 1 3 2
Client Client Client Client
Clock synchronization Clock synchronization
request packet request packet
Response packet Response packet Response packet Response packet
) carried.
1
).
3
), into it.
4
Server Server Server Server
Netw ork Netw ork Netw ork Netw ork
Work as a server Work as a server Work as a server Work as a server
automatically and automatically and automatically and automatically and
send response send response send response send response
packets packets packets packets
1-3
Chapter 1 NTP Configuration
-T ) + (T -T ))/2.
2 1 3 4
e