Path: utzoo!attcan!uunet!tank!ncar!ames!uhccux!munnari.oz.au!murtoa.cs.mu.oz.au!ditmela!yarra!melba!baby!gnb From: gnb@bby.oz (Gregory N. Bond) Newsgroups: comp.protocols.tcp-ip Subject: Need advice configuring ntpd on an isolated network Message-ID: Date: 8 Sep 89 04:05:00 GMT Sender: gnb@melba.bby.oz Distribution: comp Organization: Burdett, Buckeridge and Young Ltd. Lines: 51 Hi. I hope this is the appropriate place for this. I run an isolated network of approx 20 Sun workstations, split into 2 nets joined by a somewhat overloaded 48kbps line. We are having great problems with clock sync, as our application area (finance) has some large realtime element. We would like all hosts syncronised to within a few sec and accurate to within say 10 sec. I have measured the drift of a few handy machines (mainly the various servers, and the workstations in the systems area) by comparison with the talking clock on the telephone, and have found 2 that have drifted by about +2sec/wk over the last few weeks. One of these happened (luck!) to be my workstation (which is also an nd server and on all the time), the other a diskless node that is turned off over weekends. All the others I checked had -ve drifts of seconds per day. None of the clocks I checked had small -ve drifts. Unfortunatly our main server is drifting about -5sec/day! I have ntpd version "89/05/18 Revision: 3.4.1.6" according to the README file, patched at level 13 (according to patchlevel.h). I am wondering how I should set up my ntp system, given that I have no IP links to stratum-1 derived hosts to peer with. My initial though is to have the two least-drifting clocks as active peers (stratum 3? stratum 1?), perhaps with another if I can find one with -ve drift, and all the others as clients. The remote server will be a peer and the remote clients will be clients of the remote peer to reduce net load (ok, not that it is a lot...) Given that I have 3 main hosts peered at stratum n, each with a "natural" drift, how will they drift as a whole? If A = B = + 2sec/wk, and C = -1sec/day free running, will the combination go at -6sec/wk? -5? Some other number? (A+B+C)/3? And how would this be adjusted - could I use "date -a" on one of the three and have it propagate, or do I need to do it to all three? Another alternative is to have one host with known low drift as a stratum-1 host and peer the other 2 servers at stratum-2. I can then use date -a to adjust the server. Can I somehow inform ntp that this stratum-1 server has a known drift? In all this I'm not looking to get millisecond accuracy, indeed drift of < 5sec/week would be quite acceptable. Thankyou for your assistance. Greg. -- Gregory Bond, Burdett Buckeridge & Young Ltd, Melbourne, Australia Internet: gnb@melba.bby.oz.au non-MX: gnb%melba.bby.oz@uunet.uu.net Uucp: {uunet,pyramid,ubc-cs,ukc,mcvax,prlb2,nttlab...}!munnari!melba.bby.oz!gnb