So what you are suggesting basically is to add an application layer
sanity
checker and DoS preventer, am I right ?
More or less, yes. The main thing is to have something in front of the
clocks that can be used to block or mitigate network abuse activities like
DoS. And if this front-end is a
In message [EMAIL PROTECTED],
Robert M. Enger [EMAIL PROTECTED] wrote:
An alternate time source could be the GLONASS system.
Receivers do exist, but I have never used one.
Note that GLONASS satellites are failing frequently, and unlike GPS
satellites, are not always being replaced. Currently
The recommendations of others to place the Stratum 1 source behind another
box is indeed good operational practice. However if you _really_ want to
provide Stratum 1 services there are a couple of options
1 - Purchase a Cesium clock this is a Primary Time/Frequency standard
which does
Two relevant points on GPS/LORAN
1 - GPS has two positioning systems
1 - SPS Standard Positioning Service which is what all civillian
uses of GPS utilize for positioning and timing uses and this can
be degraded or disabled with no notice to the user community
Hi,
I wish to thank all who answered, indeed, it was helpful. But, as it
was mentioned here, any further dwelling into this particular topic would
be more appropriate in the NTP forums available, be it mailing lists or
newsgroups.
So, I would like to request that further replies
Speaking on Deep Background, the Press Secretary whispered:
Two relevant points on GPS/LORAN
1 - GPS has two positioning systems
1 - SPS Standard Positioning Service which is what all civillian
uses of GPS utilize for positioning and timing uses and this can
Derating GPS wouldn't affect the time reference functionality. Turning
off GPS entirely would seriously affect military aviation operations.
Not so:
Selective Availability (SA) is the deliberate introduction of error by
either altering the precise timekeeping of GPS satellites or the position
On Fri, 03 Oct 2003 09:59:59 -0700
Owen DeLong [EMAIL PROTECTED] wrote:
I used to work with GPS navigation / calibration. The entire system is
designed to free wheel for at least a month, and probably many months,
giving adequate performance
even if all the ground control stations were
In the immortal words of Scott McGrath ([EMAIL PROTECTED]):
1 - Purchase a Cesium clock this is a Primary Time/Frequency standard
which does not require access to a reference standard to maintain
accuracy.
This is a Stratum 0 source so once placed behind a Unix/Cisco/Juniper
Nathan J. Mehl [EMAIL PROTECTED] writes:
This is a Stratum 0 source so once placed behind a Unix/Cisco/Juniper
box you have a stratum 1 source. This will cost you 30,000 -
100,000 US per unit. The beam tube will require replacement
approx every 5 years for about
Hi,
Assuming one wanted to provide a high profile (say, at the TLD level) NTP
service, how would you go about it ?
The possibilities I encountered are diverse, the problem is not the
back-end device (be it a GPS based NTP source + atomic clock backup, based on
cesium or similar),
Assuming one wanted to provide a high profile (say, at the TLD level)
NTP
service, how would you go about it ?
First of all, NTP should be done at the geographical level, not the TLD
level. Generally, unless political reasons prevent it, you should try to
implement an NTP service that
On Thu, 2 Oct 2003 [EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks come from GPS, then
GPS is the SPOF. If they all come fram brand X manufacturer then that is
the SPOF. A commercial service should be robust and use a combination of
atomic clocks, GPS, radio
[EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks come from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
Eliot
On Thu, 2 Oct 2003, Eliot Lear wrote:
[EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks come from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
Eliot
- Antenna failure
-
[EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks
come from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
Eliot
just me wrote:
- Antenna failure
- Radio
Eliot Lear writes:
[EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks come
from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
It depends upon how low a probability
okay. two valid cases to be concerned about:
The most valid case is when we all go and buy GPS receivers from the
same vendor who turns out to have a bug or a vulnerability of some form.
The other valid case is if the defense department brought down the
sattelite system for some odd reason.
It depends upon how low a probability failure you're willing to consider
and how paranoid you are. For one thing, the U.S. National Command Authority
could decide that GPS represents a threat to national security and disable
or derate GPS temporarily or indefinitely over a limited or
On Thu, 2 Oct 2003, Eliot Lear wrote:
[EMAIL PROTECTED] wrote:
Beware the single point of failure. If all your clocks come from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
A military repositioning of the GPS
Beware the single point of failure. If all your clocks come from GPS, then
GPS is the SPOF.
Can you describe what would be involved to cause this sort of single
point of failure to fail?
please don't!
i smell my kill-subkject key coming
on the roof that blocks your antenna's view of a
portion of the sky...)Best wishes,Bob Enger-
Original Message - From: "Ariel Biener" [EMAIL PROTECTED]To:
[EMAIL PROTECTED]Sent: Thursday,
October 02, 2003 10:54 AMSubject: NTP, possible solutions, and best
implementation
Hi, As
It depends upon how low a probability failure you're willing to consider
and how paranoid you are. For one thing, the U.S. National
Command Authority
could decide that GPS represents a threat to national security
and disable
or derate GPS temporarily or indefinitely over a limited or
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