NTP
As the network topology gets more and more complex, it becomes important to
synchronize the clocks of the equipment on the entire network. Network Time
Protocol (NTP) is a TCP/IP feature that advertises the accurate time throughout the
network.
NTP ensures the consistency of the following applications:
Synchronizing the clock between two systems for incremental backup between
■
the backup server and client.
Referencing the same clock and guaranteeing correct processing for multiple
■
systems that coordinate to process a complex event.
Guaranteeing the normal operation of the inter-system (Remote Procedure
■
Call).
Recording an application when a user logs into a system, a file is modified, or
■
some other operation is performed.
Figure 7 illustrates the basic operating principle of NTP:
Figure 7 Basic Operating Principle of NTP
In page 357, Ethernet Switch A and Ethernet Switch B are connected to the
Ethernet port. They have independent system clocks. Before implementing
automatic clock synchronization on both switches, we assume that:
Before synchronizing the system clocks on Ethernet Switch A and B, the clock
■
on Ethernet Switch A is set to 10:00:00am, and the clock on B is set to
11:00:00am.
Ethernet Switch B serves as an NTP time server and Ethernet Switch A
■
synchronizes the local clock with the clock of B.
It takes 1 second to transmit a data packet from either A or B to the opposite
■
end.
NTP
357