1= Miscellaneous Commands and Options 2include::include-html.ad[] 3 4[cols="10%,90%",frame="none",grid="none",style="verse"] 5|============================== 6|image:pic/boom3.gif[]| 7{millshome}pictures.html[from 'Pogo', Walt Kelly] 8 9We have three, now looking for more. 10 11|============================== 12 13== Related Links 14 15include::includes/miscopt.adoc[] 16 17''''' 18 19== Commands and Options 20 21include::includes/misc-options.adoc[] 22 23// A subset of the tos options is described on the ntp.conf manual page. 24// If you change this, be very sure to keep that synchronized. 25 26[[tos]] 27+tos+ [+ceiling+ 'ceiling' | +floor+ 'floor' | +maxclock+ 'maxclock' | +maxdist+ 'maxdist' | +minclock+ 'minclock' | +mindist+ 'mindist' | +minsane+ 'minsane' | +orphan+ 'stratum' | +orphanwait+ 'delay']:: 28 This command alters certain system variables used by the clock 29 selection and clustering algorithms. The default values of these 30 variables have been carefully optimized for a wide range of network 31 speeds and reliability expectations. Very rarely is it necessary to 32 change the default values; but, some folks can't resist twisting the 33 knobs. It can be used to select the quality and quantity of peers used 34 to synchronize the system clock and is most useful in dynamic server 35 discovery schemes. The options are as follows: 36 +ceiling+ 'ceiling';; 37 Specify the maximum stratum (exclusive) for acceptable server 38 packets. The default is 16. See the link:discover.html[Automatic 39 Server Discovery] page for further details. 40 +floor+ 'floor';; 41 Specify the minimum stratum (inclusive) for acceptable server 42 packets. The default is 1. See the link:discover.html[Automatic 43 Server Discovery] page for further details. 44 +maxclock+ 'maxclock';; 45 Specify the maximum number of servers retained by the server 46 discovery schemes. The default is 10, which should typically be changed. 47 This should be an odd number (to most effectively outvote 48 link:ntpspeak.html[falsetickers]) typically two or three more than 49 +minclock+, plus the number of +pool+ entries. The pool entries 50 must be added as +maxclock+, but not +minclock+, also counts the +pool+ 51 entries themselves. For example, +tos maxclock 11+ with four +pool+ lines 52 would keep 7 associations. See the link:discover.html[Automatic Server 53 Discovery] page for further details. 54 +maxdist+ 'maxdistance';; 55 Specify the synchronization distance threshold used by the clock 56 selection algorithm. The default is 1.5 s. This determines both the 57 minimum number of packets to set the system clock and the maximum 58 roundtrip delay. It can be decreased to improve reliability or 59 increased to synchronize clocks on the Moon or planets. 60 +maxdisp+ 'maxdispersion';; 61 Specify the maximum dispersion used by the clock synchronization 62 algorithm. The default is 16 s. This is also the dispersion 63 assigned to missing data. See RFC 5905 for discussion. 64 +minclock+ 'minclock';; 65 Specify the number of servers used by the clustering algorithm as 66 the minimum to include on the candidate list. The default is 3. This 67 is also the number of servers to be averaged by the combining 68 algorithm. 69 +mindist+ 'mindistance';; 70 Specify the minimum distance used by the selection and anticlockhop 71 algorithm. Larger values increase the tolerance for outliers; 72 smaller values increase the selectivity. The default is .001 s. In 73 some cases, such as reference clocks with high jitter and a PPS 74 signal, it is useful to increase the value to insure the 75 intersection interval is always nonempty. 76 +minsane+ 'minsane';; 77 Specify the number of servers used by the selection algorithm as the 78 minimum to set the system clock. The default is 1 for legacy 79 purposes; however, for critical applications the value should be 80 somewhat higher (e.g. 3) but less than +minclock+. 81 +orphan+ 'stratum';; 82 Specify the orphan stratum with default 16. If less than 16 this is 83 the stratum assumed by the root servers. See the 84 link:orphan.html[Orphan Mode] page for further details. 85 +orphanwait+ 'delay';; 86 Specify the delay in seconds from the time all sources are lost 87 until orphan parent mode is enabled with default 300 s (five 88 minutes). During this period, the local clock driver and the modem 89 driver are not selectable, unless marked with the +prefer+ keyword. 90 This allows time for one or more primary sources to become reachable 91 and selectable before using backup sources, and avoids transient use 92 of the backup sources at startup. 93 94+dscp+ 'dscp':: 95 This command specifies the Differentiated Services Code Point (DSCP) 96 value that is used in sent NTP packets. The default value is 46 for 97 Expedited Forwarding (EF). 98 99''''' 100 101include::includes/footer.adoc[] 102