Retrieve NTP status information.

The Network Time Protocol (NTP) (RFC 1119, RFC 1305) allows you to synchronize computer clocks by exchanging NTP messages. The Tnm::ntp command allows you to retrieve control variables from NTP peers.

Tnm::ntp [options]

Invoking the Tnm::ntp command with options but without any command arguments allows you to retrieve and change the default values. See the description of supported options below. 

Default values are bound to a Tcl interpreter that allows you to have multiple Tcl interpreters with different defaults.

The Tnm::ntp command sends a NTP version 3 mode 6 request to host and writes status information into the Tcl array arrayName. 

After successful completion, the array will contain the following elements (RFC 1305):

This is a signed fixed-point number indicating the roundtrip delay of the peer clock relative to the local clock over the network path between them, in seconds.

This is a signed fixed-point number indicating the maximum error of the peer clock relative to the local clock over the network path between them, in seconds.

This is a signed, fixed-point number indicating the offset of the peer clock relative to the local clock, in seconds.

This is a signed integer indicating the precision of the various clocks, in seconds to the nearest power of two.

This is a shift register used to determine the reachability status of the peer, with bits entering from the least significant (rightmost) end.

A peer is considered reachable if at least one bit in this register is set to one.

This is the IP address of the peer.

This is an integer indicating the stratum of the local clock.

This is an integer counter indicating the valid samples remaining in the filter register.

It is used to determine the reachability state and when the poll interval should be increased or decreased.

This is a selector identifying the current synchronization source.

This is a signed integer indicating the precision of the various clocks, in seconds to the nearest power of two.

This is a 32-bit code identifying the particular reference clock.

sys.rootdelay

This is a signed fixed-point number indicating the total roundtrip delay to the primary reference source at the root of the synchronization subnet, in seconds.

This is a signed fixed-point number indicating the maximum error relative to the primary reference source at the root of the synchronization subnet, in seconds.

This is an integer indicating the stratum of the local clock

A textual description of the system type.

The following options control how NTP requests are send and how the ntp command deals with lost NTP packets.

-timeout time

The -timeout option defines the time the Tnm::ntp command will wait for a response. The default time is 2 seconds.

The -retries option defines how many times a request is retransmitted during the timeout interval. The default number of retries is 2.