ntp(n) Tnm Tcl Extension ntp(n)_________________________________________________________________NAMEntp - Retrieve NTP status information.
_________________________________________________________________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 vari-
ables from NTP peers.
NTP COMMANDntp [options]
Invoking the ntp command with options but without
any command arguments allows to retrieve and change
the default values. See the description of sup-
ported 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 successful comple-
tion, the array will contain the following elements
(RFC 1305):
peer.delay
This is a signed fixed-point number indicat-
ing 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 indicat-
ing the maximum error of the peer clock rel-
ative to the local clock over the network
path between them, in seconds.
peer.offset
This is a signed, fixed-point number indi-
cating the offset of the peer clock relative
to the local clock, in seconds.
peer.precision
This is a signed integer indicating the pre-
cision of the various clocks, in seconds to
the nearest power of two.
peer.reach
This is a shift register used to determine
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ntp(n) Tnm Tcl Extension ntp(n)
the reachability status of the peer, with
bits entering from the least significant
(rightmost) end. A peer is considered reach-
able 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 regis-
ter. It is used to determine the reachabil-
ity 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 pre-
cision of the various clocks, in seconds to
the nearest power of two.
sys.refid
This is a 32-bit code identifying the par-
ticular reference clock.
sys.rootdelay
This is a signed fixed-point number indicat-
ing the total roundtrip delay to the primary
reference source at the root of the synchro-
nization subnet, in seconds.
sys.rootdispersion
This is a signed fixed-point number indicat-
ing the maximum error relative to the pri-
mary 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.
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ntp(n) Tnm Tcl Extension ntp(n)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 com-
mand 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 inter-
val. The default number of retries is 2.
SEE ALSOscotty(1), Tnm(n), Tcl(n)AUTHORS
Erik Schoenfelder <schoenfr@gaertner.de>
Juergen Schoenwaelder <schoenw@cs.utwente.nl>
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