Qtech QSW-3200-28T [94/146] Brief introduction of sntp protocol

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Chapter 11 SNTP CLIENT CONFIGURATION

11.1 Brief introduction of SNTP protocol

The working theory of SNTP is as following:

SNTPv4 can be worked in three modes: unicast, broadcast (multicast) and anycast.

In unicast mode, client actively sends requirement to server, and server sends response

packet to client according to the local time structure after receiving requirement.

In broadcast and multicast modes, server sends broadcast and multicast packets to client

timing, and client receives packet from server passively.

In anycast mode, client actively uses local broadcast or multicast address to send requirement,

and all servers in the network will response to the client. Client will choose the server whose

response packet is first received to be the server, and drops packets from others. After

choosing the server, working mode is the same as that of the unicast.

In all modes, after receiving the response packet, client resolves this packet to obtain current

standard time, and calculates network transmit delay and local time complementary, and then

adjusts current time according them.

11.2 SNTP client configuration

SNTP client configuration command includes:

 Enable/disable SNTP client

 SNTP client working mode configuration

 SNTP client unicast server configuration

 SNTP client broadcast delay configuration

 SNTP client multicast TTL configuration

 SNTP client poll interval configuration

 SNTP client retransmit configuration

 SNTP client valid server configuration

 SNTP client MD5 authentication configuration

11.2.1 Enable/disable SNTP client

Use sntp client command in global configuration mode to enable SNTP client. Use no sntp

client command to disable SNTP client. After SNTP enabling, switch can obtain standard time

through internet by SNTP protocol to adjust local system time.

Enable SNTP client using following command:

 sntp client

 no sntp client

For example:

! Enable SNTP client

QTECH(config)#sntp client

11.2.2 SNTP client working mode configuration

SNTPv4 can work in three modes: unicast, broadcast (multicast), anycast. In unicast and

anycast, client sends requirement and gets the response to adjust system time. In broadcast

and multicast, client waits for the broadcast packet sent by server to adjust system time.