Article View: comp.protocols.time.ntp
Article #833Re: assistance for selecting a peer..
From: Mills
Date: Mon, 14 Dec 1992 05:08
Date: Mon, 14 Dec 1992 05:08
44 lines
2827 bytes
2827 bytes
Sanjay, First, let me suggest you use xntp3 instead of ntpd on your principal server, as this version is much more robust in the face of likely congestion on your access paths to extra-national primary servers. A couple of years back I was the guest of IIT Bombay on behalf the UN Development Program, so I have some idea of what you are up against. While I don't know the present access path, presumably via your ERNET headquarters in Bombay, I suggest you run the traceroute program to find out the particular route and inspect the file clock.txt in the pub/ntp/doc directory fia anonymous ftp on host louie.udel.edu for likely candidates. The complete distribution of ntpd, xntp3 and related programs reside in the pub/ntp directory and subdirectories on that host. Please understand the robustness of time distribution depends critically on redundancy and diversity, which means you need redundant servers and diverse access paths to multiple servers "closer" to the primary source of synchronization. The last time I visited India you had only one access path. Even in that case you should consider multiple NTP servers for your country. In view of the low network overhead of xntp3, you might consider each of your four sites as redundant and have them each peer with outside reference sources and with each other. See the various information files in the pub/ntp/doc directory and in the xntp3 distribution. There is documentation on the tickadj program in the xntp3 distribution. You need to specify a tick paramter of 9999 for those Sun platforms known to me. There are example configuration files in the distribution as well. In your part of the world, the only precision time signals suitable for connection to a computer are from the Global Position Service satellites, which require a most expensive receiver, and the OMEGA radioonavigation system (receiver made by TrueTime - see clock.txt), which is only slightly less outrageous. There is a driver for the OMEGA receiver in the xntp3 distribution (same as the GOES receiver). I challenge an enterprising grad student to cobble up a receiver for the BBC on-hour pips, which are I am told derived from precision sources and readily receivable in your country. With propagation corrections and selection of only the domestic UK transmitters, you could realize a quite accurate national time source. Dave
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Path: arc1-ca.pugleaf.net!sparky!uunet!zaphod.mps.ohio-state.edu!cs.utexas.edu!qt.cs.utexas.edu!yale.edu!spool.mu.edu!agate!ucbvax!UDEL.EDU!Mills From: Mills@UDEL.EDU Newsgroups: comp.protocols.time.ntp Subject: Re: assistance for selecting a peer.. Message-ID: <9212140008.aa22411@huey.udel.edu> Date: 14 Dec 92 05:08:52 GMT Sender: daemon@ucbvax.BERKELEY.EDU Distribution: inet Organization: The Internet Lines: 44