Ntp Configuration - Huawei Quidway S6500 Series Operation Manual

Operation Manual - System Management
Quidway S6500 Series Ethernet Switches
In the figure above, Ethernet Switch A and Ethernet Switch B are connected via the
Ethernet port. They have independent system clocks. Before implement 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 that on B is set to 11:00:00am.
Ethernet Switch B serves as an NTP time server. That is, 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.
The system clocks are synchronized as follows:
Ethernet Switch A sends an NTP packet to Ethernet Switch B. The packet carries
the timestamp 10:00:00am (T
When the NTP packet arrives at Ethernet Switch B, Ethernet Switch B adds a local
timestamp 11:00:01am (T
When the NTP packet leaves Ethernet Switch B, Ethernet Switch B adds another
local timestamp 11:00:02am (T
When Ethernet Switch A receives the acknowledgement packet, it adds a new
timestamp 10:00:03am (T
Now Ethernet Switch A collects enough information to calculate the following two
important parameters:
The delay for a round trip of an NTP packet traveling between the Switch A and B:
Delay= (T
Offset of Ethernet Switch A clock relative to Ethernet Switch B clock: offset=
( (T
2
In this way, Ethernet Switch A uses the above information to set the local clock and
synchronize it with the clock on Ethernet Switch B.
The operating principle of NTP is briefly introduced above. For details, refer to
RFC1305.

7.2 NTP Configuration

NTP is used for time synchronization throughout a network. NTP configuration tasks
include:
Configure NTP operating mode
Configure NTP ID authentication
Set NTP authentication key
Set the specified key to be reliable
Set a local interface for transmitting NTP packets
Set an external reference clock or the local clock as the master NTP clock
Enable/Disable an interface to receive NTP packets
Set control authority to access the local Ethernet Switch service.
Set maximum local sessions
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Huawei Technologies Proprietary
) that tells when it left Ethernet Switch A.
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2
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3
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7-2
Chapter 7 NTP Configuration