Specifications

4-10
System Management Software Configuration Guide for Cisco IE 2000U and Connected Grid Switches
Chapter 4 Administering the Switch
Configuring NTP
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.
Configuring the Switch to Send NTP Broadcast Packets
BEFORE YOU BEGIN
Review the “Network Time Protocol” section on page 4-2.
DETAILED STEPS
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
no shutdown Enable the port, if necessary. By default, user network
interfaces (UNIs) and enhanced network interfaces (ENIs)
are disabled, and network node interfaces (NNIs) are enabled.
Step 4
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 5
end Return to privileged EXEC mode.
Step 6
show running-config Verify your entries.
Step 7
copy running-config startup-config (Optional) Save your entries in the configuration file.
Step 8
Configure the connected peers to receive NTP broadcast
packets as described in the next procedure.