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.\"
.IX Title "LTPCLOCK 1"
.TH LTPCLOCK 1 "2016-07-07" "perl v5.24.1" "LTP executables"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
ltpclock \- LTP daemon task for managing scheduled events
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBltpclock\fR
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBltpclock\fR is a background \*(L"daemon\*(R" task that periodically performs
scheduled \s-1LTP\s0 activities.  It is spawned automatically by \fBltpadmin\fR in
response to the 's' command that starts operation of the \s-1LTP\s0 protocol, and
it is terminated by \fBltpadmin\fR in response to an 'x' (\s-1STOP\s0) command.
.PP
Once per second, \fBltpclock\fR takes the following action:
.Sp
.RS 4
First it manages the current state of all links (\*(L"spans\*(R").  In
particular, it checks the age of the currently buffered session block
for each span and, if that age exceeds the span's configured aggregation
time limit, gives the \*(L"buffer full\*(R" semaphore for that span to initiate
block segmentation and transmission by \fBltpmeter\fR.
.Sp
In so doing, it also infers link state changes (\*(L"link cues\*(R") from data rate
changes as noted in the \s-1RFX\s0 database by \fBrfxclock\fR:
.Sp
.RS 4
If the rate of transmission to a neighbor was zero but is now non-zero, then
transmission to that neighbor is unblocked.  The applicable \*(L"buffer empty\*(R"
semaphore is given if no outbound block is being constructed (enabling
start of a new transmission session) and the \*(L"segments ready\*(R" semaphore is
given if the outbound segment queue is non-empty (enabling transmission of
segments by the link service output task).
.Sp
If the rate of transmission to a neighbor was non-zero but is now zero, then
transmission to that neighbor is blocked \*(-- i.e., the semaphores triggering
transmission will no longer be given.
.Sp
If the imputed rate of transmission from a neighbor was non-zero but is now
zero, then all timers affecting segment retransmission to that neighbor are
suspended.  This has the effect of extending the interval of each affected
timer by the length of time that the timers remain suspended.
.Sp
If the imputed rate of transmission from a neighbor was zero but is now
non-zero, then all timers affecting segment retransmission to that neighbor
are resumed.
.RE
.RE
.RS 4
.Sp
Then \fBltpclock\fR retransmits all unacknowledged checkpoint segments,
report segments, and cancellation segments whose computed timeout
intervals have expired.
.RE
.SH "EXIT STATUS"
.IX Header "EXIT STATUS"
.ie n .IP """0""" 4
.el .IP "``0''" 4
.IX Item "0"
\&\fBltpclock\fR terminated, for reasons noted in the \fBion.log\fR file.  If this
termination was not commanded, investigate and solve the problem identified
in the log file and use \fBltpadmin\fR to restart \fBltpclock\fR.
.ie n .IP """1""" 4
.el .IP "``1''" 4
.IX Item "1"
\&\fBltpclock\fR was unable to attach to \s-1LTP\s0 protocol operations, probably because
\&\fBltpadmin\fR has not yet been run.
.SH "FILES"
.IX Header "FILES"
No configuration files are needed.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
No environment variables apply.
.SH "DIAGNOSTICS"
.IX Header "DIAGNOSTICS"
The following diagnostics may be issued to the \fBion.log\fR log file:
.IP "ltpclock can't initialize \s-1LTP.\s0" 4
.IX Item "ltpclock can't initialize LTP."
\&\fBltpadmin\fR has not yet initialized \s-1LTP\s0 protocol operations.
.IP "Can't dispatch events." 4
.IX Item "Can't dispatch events."
An unrecoverable database error was encountered.  \fBltpclock\fR terminates.
.IP "Can't manage links." 4
.IX Item "Can't manage links."
An unrecoverable database error was encountered.  \fBltpclock\fR terminates.
.SH "BUGS"
.IX Header "BUGS"
Report bugs to <ion\-bugs@korgano.eecs.ohiou.edu>
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIltpadmin\fR\|(1), \fIltpmeter\fR\|(1), \fIrfxclock\fR\|(1)