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Catalyst 2975 Switch Software Configuration Guide
OL-19720-02
Chapter 7 Administering the Switch
Managing the System Time and Date
Configuring NTP Broadcast Service
The communications between devices running NTP (known as
associations
) are usually statically
configured; each device is given the IP addresses of all devices with which it should form associations.
Accurate timekeeping is possible by exchanging NTP messages between each pair of devices with an
association. However, in a LAN environment, NTP can be configured to use IP broadcast messages
instead. This alternative reduces configuration complexity because each device can simply be
configured to send or receive broadcast messages. However, the information flow is one-way only.
The switch can send or receive NTP broadcast packets on an interface-by-interface basis if there is an
NTP broadcast server, such as a router, broadcasting time information on the network. The switch can
send NTP broadcast packets to a peer so that the peer can synchronize to it. The switch can also receive
NTP broadcast packets to synchronize its own clock. This section provides procedures for both sending
and receiving NTP broadcast packets.
Beginning in privileged EXEC mode, follow these steps to configure the switch to send NTP broadcast
packets to peers so that they can synchronize their clock to the switch:
To disable the interface from sending NTP broadcast packets, use the
no ntp broadcast
interface
configuration command.
This example shows how to configure a port to send NTP Version 2 packets:
Switch(config)#
interface gigabitethernet1/0/1
Switch(config-if)#
ntp broadcast version 2
Command
Purpose
Step 1
configure terminal
Enter global configuration mode.
Step 2
interface
interface-id
Specify the interface to send NTP broadcast packets, and enter
interface configuration mode.
Step 3
ntp broadcast
[
version
number
] [
key
keyid
]
[
destination-address
]
Enable the interface to send NTP broadcast packets to a peer.
By default, this feature is disabled on all interfaces.
•
(Optional) For
number
, specify the NTP version number. The
range is 1 to 3. If you do not specify a version, Version 3 is used.
•
(Optional) For
keyid
, specify the authentication key to use when
sending packets to the peer.
•
(Optional) For
destination-address
, specify the IP address of the
peer that is synchronizing its clock to this switch.
Step 4
end
Return to privileged EXEC mode.
Step 5
show running-config
Verify your entries.
Step 6
copy running-config startup-config
(Optional) Save your entries in the configuration file.
Step 7
Configure the connected peers to receive NTP broadcast packets as
described in the next procedure.
Содержание 2975 - Catalyst LAN Base Switch
Страница 36: ...Contents xxxvi Catalyst 2975 Switch Software Configuration Guide OL 19720 02 ...
Страница 40: ...xxxviii Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Preface ...
Страница 62: ...1 22 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 1 Overview Where to Go Next ...
Страница 398: ...13 30 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 13 Configuring VLANs Configuring VMPS ...
Страница 424: ...15 18 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 15 Configuring VTP Monitoring VTP ...
Страница 628: ...26 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 26 Configuring UDLD Displaying UDLD Status ...
Страница 660: ...28 8 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 28 Configuring RMON Displaying RMON Status ...
Страница 888: ...38 32 Catalyst 2975 Switch Software Configuration Guide OL 19720 02 Chapter 38 Troubleshooting Troubleshooting Tables ...