CLI: Example for Configuring Multicast Mode

In a multicast domain, the device with the most precise clock is specified as the NTP server. Clocks on other devices synchronize with the clock on the NTP server.

Prerequisites

Before the configuration, ensure that the time zone of the client is the same as that of the server. If they are inconsistent, run the clock timezone time-zone-name { add | minus } offset command to adjust the time zone.

Networking Requirements

As shown in Figure 1,

FW_C and FW_D are in the same network segment; FW_A is in another network segment; FW_F connects with the two network segments.
FW_C functions as an NTP multicast server and its local clock is a primary clock with the stratum 2. Multicast packets are sent out from GigabitEthernet 0/0/2.
FW_D and FW_A sense the multicast packets respectively on GigabitEthernet 0/0/2 of them.

Figure 1 Networking diagram of the NTP multicast mode

Configuration Roadmap

The configuration roadmap is as follows:

Configure FW_C as an NTP multicast server.
Configure FW_A and FW_D as NTP multicast clients.

Procedure

Configure the IP addresses and route based on Figure 1, add interfaces to corresponding security zones and configure security policy between security zones to ensure normal network communication. The detailed procedures are not mentioned here.
Configure an NTP multicast server.
# Set the local clock on FW_C as an NTP primary clock with stratum 2.
```
<FW_C> system-view
[FW_C] ntp-service refclock-master 2
```
# Enable the NTP server function.
```
[FW_C] undo ntp-service server disable
```
# Configure FW_C to be an NTP multicast server. NTP multicast packets are sent from GigabitEthernet 0/0/2.
```
[FW_C] interface GigabitEthernet 0/0/2
[FW_C-GigabitEthernet 0/0/2] ntp-service multicast-server
```

Configure FW_D.

# Configure FW_D to be an NTP multicast client. FW_D senses the NTP multicast packets on GE 1/0/0.

<FW_D> system-view
[FW_D] interface GigabitEthernet 0/0/2
[FW_D-GigabitEthernet 0/0/2] ntp-service multicast-client

Configure FW_A.

# Configure FW_A to be an NTP multicast client. FW_A senses the NTP multicast packets on GE 1/0/0.

<FW_A> system-view
[FW_A] interface GigabitEthernet 0/0/2
[FW_A-GigabitEthernet 0/0/2] ntp-service multicast-client

Verify the configuration.
After the configuration is complete, the clock on FW_D can be synchronized with the clock on FW_C. The clock on FW_A, however, fails to be synchronized because FW_A and FW_C are in different network segments and FW_A cannot sense the broadcast packets sent from FW_C.

Check the NTP status on FW_D and you can find that the clock status is "synchronized". That is, clock synchronization completes. The stratum of the clock on FW_D is 3, one stratum lower than that on FW_C.
```
[FW_D] display ntp-service status
 clock status: synchronized
 clock stratum: 3
 reference clock ID: 10.1.1.2
 nominal frequency: 60.0002 Hz
 actual frequency: 60.0002 Hz
 clock precision: 2^18
 clock offset: 0.66 ms
 root delay: 24.47 ms
 root dispersion: 208.39 ms
 peer dispersion: 9.63 ms
 reference time: 17:03:32.022 UTC Apr 25 2005(C61734FD.800303C0)
 synchronization state: spike (clock will be set in 1010 secs)
```

Configuration Scripts

Configuration script of FW_A

#
 sysname FW_A
#
interface GigabitEthernet 0/0/2  
 undo shutdown
 ip address 10.0.1.1 255.255.255.0
 ntp-service multicast-client
#
return

Configuration script of FW_C

#
 sysname FW_C
#
ntp-service refclock-master 2
undo ntp-service server disable
#
interface GigabitEthernet 0/0/2  
 undo shutdown
 ip address 10.1.1.2 255.255.255.0
 ntp-service multicast-server
#
return

Configuration script of FW_D

#
 sysname FW_D
#
interface GigabitEthernet 0/0/2  
 undo shutdown
 ip address 10.1.1.3 255.255.255.0
 ntp-service multicast-client
#
return