Specifications

5-24
Cisco IOS Software Configuration Guide for Cisco Aironet Access Points
OL-5260-01
Chapter 5 Administering the Access Point
Managing the System Time and Date
Cisco’s implementation of NTP does not support stratum 1 service; it is not possible to connect to a radio
or atomic clock. Cisco recommends that the time service for your network be derived from the public
NTP servers available on the IP Internet. Figure 5-1 shows a typical network example using NTP.
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.
Figure 5-1 Typical NTP Network Configuration
Configuring NTP
Cisco Aironet 1100 Series Access Points do not have a hardware-supported clock, and they cannot
function as an NTP master clock to which peers synchronize themselves when an external NTP source
is not available. These access points also have no hardware support for a calendar. As a result, the ntp
update-calendar and the ntp master global configuration commands are not available.
Catalyst 3550
switch
Catalyst 3550
switch
Catalyst 3550
switch
Catalyst 3550
switch
These switches are configured in
NTP server mode (server association)
with the Catalyst 6500 series switch.
Catalyst 6500
series switch
(NTP master)
This switch is configured as an NTP
peer to the upstream and downstream
Catalyst 3550 switches.
Catalyst 3550
switch
Workstations
Workstations
Local
workgroup
servers
43269