IBM 12.1(22)EA6 - Manual (Page 59)

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Cisco Systems Intelligent Gigabit Ethernet Switch Modules for the IBM BladeCenter, Software Configuration Guide
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Chapter 4 Administering the Switch
Managing the System Time and Date
Figure 4-1 Typical NTP Network Configuration
If the network is isolated from the Internet, Cisco’s implementation of NTP allows a device to act as
though it is synchronized through NTP, when in fact it has determined the time by using other means.
Other devices then synchronize to that device through NTP.
When multiple sources of time are available, NTP is always considered to be more authoritative. NTP
time overrides the time set by any other method.
Several manufacturers include NTP software for their host systems, and a publicly available version for
systems running UNIX and its various derivatives is also available. This software allows host systems
to be time-synchronized as well.
Configuring NTP
The switch does not have a hardware-supported clock, and it cannot function as an NTP master clock to
which peers synchronize themselves when an external NTP source is not available. The switch also has
no hardware support for a calendar. As a result, the ntp update-calendar and the ntp master global
configuration commands are not available.
This section contains this configuration information:
• Default NTP Configuration, page 4-4
• Configuring NTP Authentication, page 4-4
• Configuring NTP Associations, page 4-5
• Configuring NTP Broadcast Service, page 4-6
• Configuring NTP Access Restrictions, page 4-7
• Configuring the Source IP Address for NTP Packets, page 4-9
• Displaying the NTP Configuration, page 4-10
Catalyst 2950, 2955,
or 3550 switch
BladeCenter
Catalyst 2950, 2955,
or 3550 switch
These switches are configured in
NTP server mode (server association)
with the Catalyst 6500 series switch.
Catalyst 6500
series switch
(NTP master)
Catalyst 2950, 2955,
or 3550 switch
Local
workgroup
servers
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