3Com Switch 7750 Configuration Guide
Configuration Example 767
<SW7750-2> system-view
[s7500-2]
# Enter VLAN-interface 2 view.
[SW7750-2] interface Vlan-interface 2
[SW7750-2-Vlan-Interface2]
# Configure Switch 7750-2 to be a broadcast client.
[SW7750-2-Vlan-interface2] ntp-service broadcast-client
The above configuration configures Switch 7750-1 and Switch 7750-2 to listen to
broadcast packets through their VLAN interface 2, and 3Com3 to send broadcast
packets through VLAN interface 2. Because Switch 7750-2 does not reside in the
same network segment with 3Com3, Switch 7750-2 cannot receive broadcast
packets sent by 3Com3, while Switch 7750-1 is synchronized to 3Com3 after
receiving broadcast packets sent by 3Com3.
View the status of Switch 7750-1 after the synchronization.
[SW7750-1] display ntp-service status
Service status: enabled
Clock status: synchronized
Clock stratum: 3
Reference clock ID: 3.0.1.31
Nominal frequency: 250.0000 Hz
Actual frequency: 249.9992 Hz
Clock precision: 2^19
Clock offset: 198.7425 ms
Root delay: 27.47 ms
Root dispersion: 208.39 ms
Peer dispersion: 9.63 ms
Reference time: 17:03:32.022 UTC Thu Sep 6 2001 (BF422AE4.05AEA86C)
The output information indicates that Switch 7750-1 is synchronized to 3Com3,
with the clock stratum of 3, one stratum higher than 3Com3.
# View the information about the NTP sessions of Switch 7750-1 and you can see
that a connection is established between Switch 7750-1 and 3Com3.
[SW7750-1] display ntp-service sessions
source reference stra reach poll now offset delay disper
**************************************************************************
[1]3.0.1.31 127.127.1.0 2 1 64 377 26.1 199.53 9.7
note: 1 source(master),2 source(peer),3 selected,4 candidate,5 configured
NTP Multicast Mode
Configuration
Network requirements
3Com3 sets the local clock to be NTP master clock, with the clock stratum of 2. It
advertises multicast packets through VLAN interface 2.
Configure Switch 7750-1 and Switch 7750-2 to listen to multicast packets
through their VLAN interface 2.
n
This example assumes that 3Com3 is a switch that supports the local clock being
the master clock.