shaver@atanasoff.cs.iastate.edu (Dave Shaver) (02/08/89)
I know that "network time servers" exist on the Internet. Here's the
list I have:
192.5.8.1 time
128.9.2.129 time1 isi
128.8.10.1 umd1 time2
128.5.0.1 ford1 time3
128.116.64.2 ncar time4
Now my question is how to use them. How does one ask any of these
machines for the correct time? On which IP port number and using what
protocol can I get the correct time? Port numbers I know of: 13, 37,
and 525 (UNIX timed). I know that you can just connet to port 13 and
read the time. What is the best way of doing this? Any help would be
appreciated.
My second problem is UNIX timed. My goal is to get the "correct" time
from a time server and then pass it out on our LAN via timed. We have
an HP 350 running HP-UX (System V/BSD "mix"). Has anyone ported
the 4.3 BSD timed to HP-UX or SYSV? (This could be hard without
the adjtime(2) system call.)
Another option would be to use something other than timed. Any other
comments or ideas are welcomed.
/\ Dave Shaver -=*=- CS Systems Support Group, Iowa State University
\\ UUCP: {hplabs!hp-lsd, uunet!umix!sharkey}!atanasoff!shaver
\/ Internet: shaver@atanasoff.cs.iastate.eduMills@udel.edu (02/09/89)
Dave, First, please note your list of truechimers is out of date. Fetch the file pub/ntp/clock.txt from louie.udel.edu as the latest list of servers that chime the Network TIme Protocol (NTP). See RFC-1059 for a description of NTP and either Louie Mamakos (louie@trantor.umd.edu) or Mike Petry (petry@trantor.umd.edu) for the ntpd Unix daemon. The list of NTP servers cited includes only the Fuzzball NTP servers, both primary (i.e. directly connected to a radio clock) or secondary (derives time from a primary clock via the network). There are many more NTP servers, a few primary and a lot secondary, using ntpd. A message to the ntp@trantor.edu list should smoke out a few near you. As suggested in RFC-1059, you may find your needs well met by peering with a couple of the primary servers on the NSFNET Bluebone (e.g. NCAR, SDSC or UIUC) and a couple of nearby secondary servers. NTP is not the only clock in town, even on the Fuzzballs. I found a couple of thousand responded to either UDP/TIME (37), UDP/NTP (113) or ICMP/Timestamp in a survey a year ago. While TCP-based time protocols such as TCP/DAYTIME (13) are available on many machines, I for one have strongly discouraged using TCP for that, as system resources can quickly become congested if large numbers of connections are clanking open and close. Both TIME and NTP can operate over UDP without any state storage in the server and with only minimal state storage in the client. While most organizations I know of that use NTP distribute time within their system with NTP as well, there is no reason in principle why timed could not be used within the LAN, other than a small change to the master-election algorithm. A query to the ntp@trantor.umd list will probably smoke somebody that has already done that. While not strictly part of NTP itself, the full accuracy of the service requires that the local-clock adjustment mechanism by engineered. Both the Fuzzballs and ntpd do a very careful job of that using phase-lock loop technology. In principle, timed could do that as well. Maybe somebody will even make that happen. Dave
tai%hpdstma@HP-SDE.SDE.HP.COM (Tai Jin) (02/09/89)
I'm not sure if anyone has ported timed to HP-UX, but we have ported ntp. Since HP-UX doesn't have an adjtime(2) system call I had to write an emulator (as a user process) which works on 6.0/2.0 or later releases. We don't have the latest ntp ported yet (I'm not sure if the latest code is stable yet), but if you need something now I can give you what we have that works. ...tai