ntp(n) Tnm Tcl Extension ntp(n)
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NAME
ntp - Retrieve NTP status information.
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DESCRIPTION
The Network Time Protocol (NTP) (RFC 1119, RFC 1305) allows to synchronize computer clocks by exchanging NTP messages. The ntp command
allows to retrieve control variables from NTP peers.
NTP COMMAND
ntp [options]
Invoking the ntp command with options but without any command arguments allows to retrieve and change the default values. See the
description of supported options below. Default values are bound to a Tcl interpreter which allows to have multiple Tcl interpreter
with different defaults.
ntp [options] host arrayName
The ntp command sends a NTP version 3 mode 6 request to host and writes status information into the Tcl array arrayName. After suc-
cessful completion, the array will contain the following elements (RFC 1305):
peer.delay
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.
peer.dispersion
This is a signed fixed-point number indicating the maximum error of the peer clock relative to the local clock over the net-
work path between them, in seconds.
peer.offset
This is a signed, fixed-point number indicating the offset of the peer clock relative to the local clock, in seconds.
peer.precision
This is a signed integer indicating the precision of the various clocks, in seconds to the nearest power of two.
peer.reach
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.
peer.srcadr
This is the IP address of the peer.
peer.stratum
This is an integer indicating the stratum of the local clock.
peer.valid
This is an integer counter indicating the valid samples remaining in the filter register. It is used to determine the reacha-
bility state and when the poll interval should be increased or decreased.
sys.peer
This is a selector identifying the current synchronization source.
sys.precision
This is a signed integer indicating the precision of the various clocks, in seconds to the nearest power of two.
sys.refid
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.
sys.rootdispersion
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.
sys.stratum
This is an integer indicating the stratum of the local clock
sys.system
A textual description of the system type.
NTP OPTIONS
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 ntp command will wait for a response. The time is defined in seconds with a default of 2
seconds.
-retries number
The -retries option defines how many times a request is retransmitted during the timeout interval. The default number of retries is
2.
SEE ALSO
scotty(1), Tnm(n), Tcl(n)
AUTHORS
Erik Schoenfelder <schoenfr@gaertner.de>
Juergen Schoenwaelder <schoenw@cs.utwente.nl>
Tnm ntp(n)