3Com SuperStack 4 Configuration Manual page 357

Configure
Authentication-enabled
NTP Server Mode
[switch3-Vlan-Interface2]ntp-service multicast-server
Configure Switch 4:
1 Enter System View.
<switch4> system-view
2 Enter Vlan-interface2 view.
[switch4]interface vlan-interface 2
3 Enable multicast client mode.
[switch4-Vlan-Interface2]ntp-service multicast-client
Configure Switch 1:
1 Enter System View.
<switch1> system-view
2 Enter Vlan-interface2 view.
[switch1]interface vlan-interface 2
3 Enable multicast client mode.
[switch1-Vlan-Interface2]ntp-service multicast-client
The above examples configure Switch 4 and Switch 1 to receive multicast
messages from Vlan-interface2, Switch 3 multicast messages from
Vlan-interface2. Since Switch 1 and Switch 3 are not located on the same
segments, Switch 1 cannot receive the multicast packets from Switch 3, while
Switch 4 is synchronized by Switch 3 after receiving the multicast packet.
Network Requirements
Switch 1 sets the local clock as the NTP master clock at stratum 2. Switch 2 sets
Switch 1 as its time server in server mode and itself in client mode and enables
authentication. Networking Diagram
See Figure 94.
Configuration Procedure
Configure Switch 1:
1 Enter System View.
<switch1> system-view
2 Set the local clock as the master NTP clock at stratum 2.
[switch1]ntp-service refclock-master 2
Configure Switch 2:
1 Enter System View.
<switch2> system-view
2 Set Switch 1 as time server.
[switch2]ntp-service unicast-server 1.0.1.11
3 Enable authentication.
Typical NTP Configuration Examples 369