Phil W Lee wrote:
William Unruh un...@invalid.ca considered Sat, 13 Sep 2014 11:56:37
+ (UTC) the perfect time to write:
On 2014-09-12, Martin Burnicki martin.burni...@meinberg.de wrote:
William Unruh wrote:
No idea why a fudge parameter would be complicated. If you wanted to use
ntpd
Rob schrieb:
Paul tik-...@bodosom.net wrote:
On Fri, Sep 12, 2014 at 4:03 AM, Martin Burnicki
martin.burni...@meinberg.de wrote:
+1
However, path asymmetry includes
I think you're abusing the conventional notion of asymmetric latency.
Uncorrected bandwidth asymmetry will result in offsets
William Unruh wrote:
On 2014-09-12, Martin Burnicki martin.burni...@meinberg.de wrote:
William Unruh wrote:
No idea why a fudge parameter would be complicated. If you wanted to use
ntpd itself to figure out the assymmetry, that could well be
complicated. But if it is a fixed offset, I cannot
On 2014-09-15, Martin Burnicki martin.burni...@meinberg.de wrote:
Phil W Lee wrote:
William Unruh un...@invalid.ca considered Sat, 13 Sep 2014 11:56:37
+ (UTC) the perfect time to write:
On 2014-09-12, Martin Burnicki martin.burni...@meinberg.de wrote:
William Unruh wrote:
No idea why a
Replying to Charles Elliott:
The offset may be a function of distance. Try this experiment:
Set up your ntp.conf file to have three servers . . . :
1. A relatively unused stratum 1 or 2 server as close to you as possible
2. A relatively unused stratum 1 or 2 server about 1,000 miles away
Le 13 sept. 2014 à 07:46, Rich Wales a écrit :
-68.65.164.12.PPS.1 u 13 16 3728.168 -2.126 4.585
-171.67.203.16 204.63.224.702 u2 16 3339.6892.146 3.930
Any thoughts?
I should have added
netstat -i
are you dropping packets,
Le 13 sept. 2014 à 07:46, Rich Wales a écrit :
Replying to Charles Elliott:
The offset may be a function of distance. Try this experiment:
Set up your ntp.conf file to have three servers . . . :
1. A relatively unused stratum 1 or 2 server as close to you as possible
2. A relatively
On 2014-09-12, Martin Burnicki martin.burni...@meinberg.de wrote:
William Unruh wrote:
No idea why a fudge parameter would be complicated. If you wanted to use
ntpd itself to figure out the assymmetry, that could well be
complicated. But if it is a fixed offset, I cannot see how that would be
On Sat, Sep 13, 2014 at 1:46 AM, Rich Wales ri...@richw.org wrote:
Any thoughts?
Something is wrong with your home machine but there's nothing you can
do with stock NTP to fix your offset.
As posted earlier I see exactly the same ~2ms offset. However as
noted -- given that you're on the same
On Thu, 11 Sep 2014 21:09:46 +, Rob wrote:
Paul tik-...@bodosom.net wrote:
On Thu, Sep 11, 2014 at 2:29 PM, William Unruh un...@invalid.ca wrote:
I doubt that NAT would add much assymetry
NAT is symmetric. Otherwise it wouldn't work. But I don't see how
that's part of anything at
Harlan Stenn wrote:
There are a bunch of issues here, and I don't think there is a simple
answer.
For starters, there is static asymmetry and dynamic asymmetry.
One of the core issues is that NTP is frequently multihop, and the
routing for at least some of these connections can spontaneously
William Unruh wrote:
No idea why a fudge parameter would be complicated. If you wanted to use
ntpd itself to figure out the assymmetry, that could well be
complicated. But if it is a fixed offset, I cannot see how that would be
complicated and it ihas already been implimented in the refclock
Rob wrote:
An offset between two GPS synced servers by definition means path asymmetry.
+1
However, path asymmetry includes
- systematic asymmetry (e.g. ADSL) on one ore more (!) parts of the path
between 2 nodes
- errors due to different link speeds, e.g 100 MBit from 1 switch port
to
Martin Burnicki martin.burni...@meinberg.de wrote:
- NAT doesn't hurt at all, unless you are trying to use NTP's authentication
NAT in itself does not hurt, but when you want to be a timeserver for
a large number of clients, it can be a problem.
Many home routers have no static NAT but only
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
- NAT doesn't hurt at all, unless you are trying to use NTP's authentication
NAT in itself does not hurt, but when you want to be a timeserver for
a large number of clients, it can be a problem.
Many home routers have no static
Martin Burnicki martin.burni...@meinberg.de wrote:
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
- NAT doesn't hurt at all, unless you are trying to use NTP's authentication
NAT in itself does not hurt, but when you want to be a timeserver for
a large number of clients, it
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
When you serve thousands of clients, this tends to overflow the NAT
table or stress the lookup code so much that it overloads the CPU.
Haven't had such case, yet since
Terje Mathisen terje.mathi...@tmsw.no wrote:
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
Rob wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
When you serve thousands of clients, this tends to overflow the NAT
table or stress the lookup code so much that it
On Thu, Sep 11, 2014 at 3:50 PM, mike cook michael.c...@sfr.fr wrote:
Yup, AsymmetricDSL does have different up/down bit rates. What I really
meant was that the difference would not explain his issue.
ex: with a 12Mbps down rate and 1.3Mbps up rate, the ratio is around 40usec
to 300usec
Paul tik-...@bodosom.net wrote:
On Fri, Sep 12, 2014 at 4:03 AM, Martin Burnicki
martin.burni...@meinberg.de wrote:
+1
However, path asymmetry includes
I think you're abusing the conventional notion of asymmetric latency.
Uncorrected bandwidth asymmetry will result in offsets between
On Fri, Sep 12, 2014 at 11:48 AM, Rob nom...@example.com wrote:
No, not link-speed asymmetry but propagation-time asymmetry
Sure, you can say that after the fact. Only one other person in this
conversation *particularly, not the OP* meant that. As I said the
conventional notion of asymmetric
William Unruh wrote:
Not if you have gps reference at both ends, though why you would not use
the gps as the timesource then I do not know.
The case mentioned by the original poster is just one possible reason.
If you have a GPS controlled NTP server at home, and a fast internet
connection,
Rob wrote:
Ok you are right. In fact I filed bug #2598 myself for a similar
situation... In my case I wanted to compensate for the delay asymmetry
for external users using my GPS reference via my ADSL line. So I
would like to apply such a fudge command to a network interface, not
to a peer
Martin Burnicki martin.burni...@meinberg.de wrote:
This is also what Rob has mentioned in another post of this thread, and
I agree with Rob that a one approach could be to specify (and configure
for ntpd) the systematic error due to asymmetry of your internet connection.
However, this can
On 2014-09-11, Martin Burnicki martin.burni...@meinberg.de wrote:
William Unruh wrote:
Not if you have gps reference at both ends, though why you would not use
the gps as the timesource then I do not know.
The case mentioned by the original poster is just one possible reason.
If you have a
On Tue, Sep 9, 2014 at 6:58 PM, Harlan Stenn st...@ntp.org wrote:
The issue is that the huff-n-puff filter will work in the case where a
symmetrical delay becomes asymmetric, and it will tolerate or
accommodate an asymmetric delay (caused by a large download, for
example) for some period of
Paul tik-...@bodosom.net wrote:
Not to suggest that someone is doing something unreasonable but again
why does time derived from the back-up clock need to be as accurate as
the local clock (say .5ms versus 2ms)? If there's a legitimate need
then trying to solve the problem with the wrong tool
Paul tik-...@bodosom.net wrote:
As an aside has anyone tried shaping traffic to make the
upstream/downstream latencies similar? It would seem more efficient
to apply network solutions to network problems if possible.
That does not work. The asymmetry is not caused by traffic but by
modem
On Thu, Sep 11, 2014 at 12:48 PM, Rob nom...@example.com wrote:
That does not work. The asymmetry is not caused by traffic but by
modem parameters.
The asymmetry is caused by asymmetric latency which is caused (for our
purposes) by asymmetric line speeds. Traffic shaping can change
various
Le 11 sept. 2014 à 18:48, Rob a écrit :
Paul tik-...@bodosom.net wrote:
As an aside has anyone tried shaping traffic to make the
upstream/downstream latencies similar? It would seem more efficient
to apply network solutions to network problems if possible.
That does not work. The
On 2014-09-11, Rob nom...@example.com wrote:
Martin Burnicki martin.burni...@meinberg.de wrote:
This is also what Rob has mentioned in another post of this thread, and
I agree with Rob that a one approach could be to specify (and configure
for ntpd) the systematic error due to asymmetry of
On 2014-09-11, mike cook michael.c...@sfr.fr wrote:
Le 11 sept. 2014 ? 18:48, Rob a ?crit :
Paul tik-...@bodosom.net wrote:
As an aside has anyone tried shaping traffic to make the
upstream/downstream latencies similar? It would seem more efficient
to apply network solutions to network
On Thu, Sep 11, 2014 at 2:29 PM, William Unruh un...@invalid.ca wrote:
I doubt that NAT would add much assymetry
NAT is symmetric. Otherwise it wouldn't work. But I don't see how
that's part of anything at hand.
And yes the A in ADSL stands for Asymmetric. If you see the word
home in
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM, Rich Wales ri...@richw.org wrote:
My home LAN is connected to my school's network via a cable modem.
If we make the (safe) assumption of a common cable ISP/FiOS in the
Le 11 sept. 2014 à 21:08, Paul a écrit :
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM, Rich Wales ri...@richw.org wrote:
My home LAN is connected to my school's network via a cable modem.
If we make the
: Re: [ntp:questions] Compensating for asymmetric delay on a
per-peer/server basis?
Le 11 sept. 2014 à 18:48, Rob a écrit :
Paul tik-...@bodosom.net wrote:
As an aside has anyone tried shaping traffic to make the
upstream/downstream latencies similar? It would seem more efficient
Paul tik-...@bodosom.net wrote:
On Thu, Sep 11, 2014 at 2:29 PM, William Unruh un...@invalid.ca wrote:
I doubt that NAT would add much assymetry
NAT is symmetric. Otherwise it wouldn't work. But I don't see how
that's part of anything at hand.
I never claimed it is part of the asymmetry, I
mike cook michael.c...@sfr.fr wrote:
Le 11 sept. 2014 à 18:48, Rob a écrit :
Paul tik-...@bodosom.net wrote:
As an aside has anyone tried shaping traffic to make the
upstream/downstream latencies similar? It would seem more efficient
to apply network solutions to network problems if
mike cook michael.c...@sfr.fr wrote:
Le 11 sept. 2014 à 21:08, Paul a écrit :
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM, Rich Wales ri...@richw.org wrote:
My home LAN is connected to my school's network via
There are a bunch of issues here, and I don't think there is a simple
answer.
For starters, there is static asymmetry and dynamic asymmetry.
One of the core issues is that NTP is frequently multihop, and the
routing for at least some of these connections can spontaneously change.
Declaring an
On 11/09/14 22:11, Rob wrote:
mike cook michael.c...@sfr.fr wrote:
Le 11 sept. 2014 à 21:08, Paul a écrit :
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM, Rich Wales ri...@richw.org wrote:
My home LAN is
David Woolley david@ex.djwhome.demon.invalid wrote:
On 11/09/14 22:11, Rob wrote:
mike cook michael.c...@sfr.fr wrote:
Le 11 sept. 2014 à 21:08, Paul a écrit :
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM,
mike cook wrote:
Le 11 sept. 2014 à 21:08, Paul a écrit :
On Thu, Sep 11, 2014 at 2:08 PM, mike cook michael.c...@sfr.fr wrote:
Did I miss something?
On Tue, Sep 9, 2014 at 3:17 PM, Rich Wales ri...@richw.org wrote:
My home LAN is connected to my school's network via a cable modem.
If we
Rich Wales ri...@richw.org wrote:
Replying to Rob:
Yes, you can use: fudge 1.2.3.4 time1 -0.002 or similar.
see the manual.
This didn't work. And the following error message appeared in my syslog:
inappropriate address 10.0.229.163 for the fudge command,
line ignored
As best
Subject: Re: [ntp:questions] Compensating for asymmetric delay on a
per-peer/server basis?
Rich Wales ri...@richw.org wrote:
Replying to Rob:
Yes, you can use: fudge 1.2.3.4 time1 -0.002 or similar.
see the manual.
This didn't work. And the following error message appeared in my
On 2014-09-09, Harlan Stenn st...@ntp.org wrote:
The issue is that the huff-n-puff filter will work in the case where a
symmetrical delay becomes asymmetric, and it will tolerate or
accommodate an asymmetric delay (caused by a large download, for
example) for some period of time.
This is a
Is there a way to compensate for asymmetric delay to/from one specific
peer or server?
My home LAN is connected to my school's network via a cable modem.
There appears to be a consistent asymmetry of 2-3 msec between my home
and the school's network. I can see this by comparing the time on
my
Rich Wales ri...@richw.org wrote:
Is there a way to compensate for asymmetric delay to/from one specific
peer or server?
My home LAN is connected to my school's network via a cable modem.
There appears to be a consistent asymmetry of 2-3 msec between my home
and the school's network. I can
Replying to Rob:
Yes, you can use: fudge 1.2.3.4 time1 -0.002 or similar.
see the manual.
This didn't work. And the following error message appeared in my syslog:
inappropriate address 10.0.229.163 for the fudge command,
line ignored
As best I can tell from the online manual, the
On Tue, Sep 9, 2014 at 5:11 PM, Rich Wales ri...@richw.org wrote:
I checked the manual before asking my question
Good start, so many don't -- even years later.
I might point you at The Huff-n'-Puff Filter but perhaps you could
explain your concern. An error in the small millisecond range is
The issue is that the huff-n-puff filter will work in the case where a
symmetrical delay becomes asymmetric, and it will tolerate or
accommodate an asymmetric delay (caused by a large download, for
example) for some period of time.
This is a case where there is reasonably-understood asymmetry for
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