[comp.protocols.tcp-ip] A good day for timewarps

Mills@UDEL.EDU (01/18/88)

Folks,

Two of the four Internet timetellers normally synchronized to NBS radio time
have blown their springs. ISI (128.9.2.129) is ticking one year in the past
and NCAR (128.116.64.3) is ticking one day in the future. The remaining two,
UMD1 (128.8.10.1) and FORD1 (128.5.0.1), are presently in-chime with NBS;
however, access to FORD1 is frequently unstable due to network problems. Since
all NSFNET Backbone fuzzballs except U Maryland are synchronized to NCAR,
these tockers will also be ticking one day in the future.

At ISI the system startup file must be updated to the present year.
Apparently, probably due to known hardware problems, the file was restored as
of last year. At NCAR the bugfix I left on the disk there must be installed.
Cornell was notified of the NCAR bug last week but so far has not installed
the fix. I cannot do either of these things from here.

Dave

swb@TCGOULD.TN.CORNELL.EDU (Scott Brim) (01/18/88)

I'd like to ask everyone **not** to use NCAR.NSF.NET (128.116.64.3) or
any of the other *.nsf.net fuzzballs as time servers.  Granted time
service doesn't take too many resources, the NCAR fuzzball is a
central node in NSFNET, with about 30-40 institutions on the other
side of the ethernet it is connected to and lots of traffic going
through it on its point-to-point links.  It is already so congested
that it spasms from time to time.  A few cycles here and there at this
point make a tremendous difference in the survivability of NSFNET.  So
PLEASE use one of the others to NTP-peer with.
						Scott

CASNER@VENERA.ISI.EDU (Stephen Casner) (01/20/88)

Folks,
	The system startup file for WWVB.ISI.EDU has been reentered to
bring it up to 1988, so it should once again be ticking the correct time.

								-- Steve
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Mills@UDEL.EDU (01/21/88)

Steve,

Great. NCAR is apparently ticking to-date as well. Have you any idea why
I can't barge into the WWVB fuzzy and refertilize its disk?

All stations, be advised reports from our commando unit operating in
Vienna, VA, has just liberated a WWVB clock (which used to tick at
Linkabit). Said clock and commando also sighted leaving Metroliner
Wilmington, DE. There are persistent rumors to effect this clock may
soon tick from U Delaware. This was a very clean operation with the
only casulty a Property Control Officer and a DSSW beancounter or two.

Dave

perry@MCL.UNISYS.COM (Dennis Perry) (01/21/88)

Dave, I am disappointed.  Beancounters usually are high priority
and to only take out two of them is not very good field operations :-)

dennis

Mills@UDEL.EDU (01/22/88)

Dennis,

Yeah, but I sure got funny looks as I hauled the clock and antenna through
Union Station. I just told the doorperson the antenna was a new-model M16
and got wonderful service. It seems to be working okay at the moment, so
its appearance on the net should be eminent (sic).

Dave

Mills@UDEL.EDU (01/22/88)

Scott,

I concur with your feeling that the NCAR fuzzball should be protected from
cycle stealers as much as possible, but maybe you are missing something.
First, application-level services, including NTP, are run at the lowest
priority level in the multi-level scheduler, so that packet-forwarding
functions always take precedence. Furthermore, the memory allocations
are disjoint, so that even relatively large numbers of UDP users do
not impact the resources used by packet-forwarding functions.

Notwithstanding the above, I would very much recommend the use of the
backbone fuzzies to provide time service directly to their Ethernet
population simply to avoid those time-service packets transiting the
seriously overloaded backbone links to other time servers removed from
the backbone. As you know, the fuzzballs are carefully synchronized
to various radio clocks using their local-net routing protocol, so
there is no need for time-service packets between them or for timewatchers
to chime any but the nearest fuzzball as the ethernet flies.

What I think is a much more productive strategy is to suggest to your
timewatchers to avoid the urge to chime any particular fuzzball with
multiple hosts on the same network. Far better to chime with one host
using NTP and then redistribute time locally. It would seem that each
backbone fuzzball could serve as chimee for any or all the nets it
normally serves in its respective configuration. This would avoid
the chimepackets even coming near the overloaded serial lines.

Dave