Hi! Thanks for your reply. My comments bellow.
On 1 September 2011 18:24, unruh <[email protected]> wrote: > On 2011-09-01, Miguel Gon?alves <[email protected]> wrote: > > Hi all! > > > > I have two internal FreeBSD with GPS receivers attached (Garmin 18 LVC: > > 10.0.2.10 / Sure Evaluation Board:10.0.2.9). Both machines are on the > same > > LAN segment (VLAN). > > > > For redundancy, I've configured a Cisco switch as a stratum 2 server. > Here's > > the relevant information: > > > > $ ntpq -pcrv 10.0.2.254 > > remote refid st t when poll reach delay offset > > jitter > > >============================================================================== > > +ntp0.as34288.ne .PPS. 1 u 814 1024 377 72.750 -1.084 > > 0.780 > > +canon.inria.fr .GPSi. 1 u 399 1024 377 55.110 0.218 > > 0.400 > > What are those machines? You have names rather than IP addresses. > Are they your pps machines? No. This is a stratum 2 server and it gets the time from stratum 1 servers thus the names and not IP addresses. > I have another machine (Linux, CentOS 5.6) that is a client to these > stratum > > 1 FreeBSD machines. Here's the relevant information: > > > > $ ntpq -pcrv 10.0.2.2 > > remote refid st t when poll reach delay offset > > jitter > > >============================================================================== > > +10.0.2.10 .GPS. 1 u 211 256 377 0.159 -0.139 > > 0.350 > > *10.0.2.9 .GPS. 1 u 71 256 377 0.166 -0.136 > > 0.468 > > That is a huge offset for being on the same lan, and for being only > .15ms away. It's really strange... I am getting on another LAN connected to this one these values... $ ntpq -p 10.0.99.99 remote refid st t when poll reach delay offset jitter ============================================================================== *10.0.2.10 .GPS. 1 u 21 256 377 0.173 0.196 0.008 +10.0.2.9 .GPS. 1 u 93 256 377 0.175 0.191 0.014 +10.0.2.254 81.94.123.16 2 u 149 256 377 0.583 -6.884 0.152 This is a FreeBSD embedded PBX machine running Asterisk. The machine is mostly idle. What kind of offsets should I get with local machines? Here in Portugal our Time Dissemination Authority has two stratum 2 servers. One of them shows this: $ ntpq -p ntp02.oal.ul.pt remote refid st t when poll reach delay offset jitter ============================================================================== *ntp01.oal.ul.pt .GPS. 1 u 113 128 377 5.125 -0.263 0.320 ntp03.oal.ul.pt .INIT. 16 u - 1024 0 0.000 0.000 0.000 -ntp04.oal.ul.pt 194.117.9.138 2 u 57 128 377 0.377 -0.056 0.080 +ntp05.oal.ul.pt .GPS. 1 u 62 128 377 0.296 0.128 0.058 +ntp06.oal.ul.pt .IRIG. 1 u 56 128 377 0.310 0.104 0.045 Assuming ntp04, ntp05 and ntp06 are on the same LAN I see offsets higher than 100 us. Is it possible to decrease these numbers? > tick# ntpdate -p8 -q tock > > server 10.0.2.9, stratum 1, offset -0.000004, delay 0.02577 > > 1 Sep 10:23:45 ntpdate[3537]: adjust time server 10.0.2.9 offset > -0.000004 > > sec > > That probably says more about the symmetry of the path than the offset > of the machine. OK. But this is a 24 port Gigabit switch from Cisco. I wouldn't expect asymmetry but it could be. > Are my GPS clocks OK? Does this happen due to the network latency? Are my > > stratum 2 servers OK? > > Your GPS seems to be consistant with each other ( that is all one can > say without another time source to compare them to). Your offsets are > large compared with the delay times ( was the machine recently heated > up due to working harder?) All these machines sit in a room temperature controlled at 20 ºC. 10.0.2.2 is a backup server that just does some work every hour but nothing huge. 10.0.2.2 has been running for quite a while and it doesn't seem to get lower offsets. Could it be because it's running Linux? I've heard Linux is not as good as FreeBSD for time keeping. Thanks! Regards, Miguel _______________________________________________ questions mailing list [email protected] http://lists.ntp.org/listinfo/questions
