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Thread: Re: questions about current NTP protocol draft
Re: questions about current NTP protocol draft
user name
 2007-04-04 16:55:35 

  


  

    

I asked Tim to check the reformatted xml to make sure nothing got corrupted in the process. 


The equation in question is: 


 


Karen


 


   In the next step the shift register stages are copied to a temporary
   list and the list sorted by increasing delta.  Let i index the stages
   starting with the lowest delta.  If the first tuple epoch t_0 is not
   later than the last valid sample epoch p.t, the routine exits without
   affecting the current peer variables.  Otherwise, let epsilon_i be
   the dispersion of the ith entry, then
                     i=n-1
                     ---     epsilon_i
      capepsilon =         ----------
                      /        (i+1)
                     ---     2
                     i=0

   is the peer dispersion p.disp.  Note the overload of epsilon, whether
   input to the clock filter or output, the meaning should be clear from
   context.






From: ntpwg-bounces+karen.odonoghue=navy.millists.ntp.isc.org on behalf of Greg Dowd
Sent: Wed 4/4/2007 4:22 PM
To: Plunkett, Timothy R CIV NSWCDD, W13; ntpwglists.ntp.isc.org
Subject: Re: [ntpwg] questions about current NTP protocol draft





I'm honestly not EXACTLY sure what version is what in the xml domain but I'll vote.


 


1) I don't see capepsilon in the non xml version.  Can you quote the string or equation here? ; In any case, capepsilon is root dispersion.  If the notes or context allows you to determine that the variable in question is indeed root dispersion then EPSILON would be correct in the latest version.


 


2) Yes, sqrt of the sum of the squares.  


 


 


Greg Dowd 
gdowd at symmetricom dot com (antispam format) 
Symmetricom, Inc. 
www.symmetricom.com 
"The current implementation is non-obvious and may need to be improved." 




 






From: ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org [mailto:ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org] On Behalf Of Plunkett, Timothy R CIV NSWCDD, W13
Sent: Wednesday, April 04, 2007 2:02 PM
To: ntpwglists.ntp.isc.org
Subject: [ntpwg] questions about current NTP protocol draft





I am currently editing the XML version of the latest NTPv4 protocol draft.  I noticed the following two things that I was hoping that someone could clarify for me.


1.  Should the equation for capepsilon in section 10 be for a variable called EPSILON instead?  I know that there has been an effort to remove all the "cap" variables and I think this is a leftover.


2.  Should the equation for PSI in section 11.2.3 have a square root function in it?  Seems like PSI should equal SQRT [(PSI_s)^2 + (PSI_p)^2].  If preferred I could also raise it to the one half power as well.


Thanks, 


Tim 


*********************************************************** 
Timothy R. Plunkett 
NSWC-DD, Code W13 
Building 1500 Room A122A 
17214 AVENUE B SUITE 100 
DAHLGREN, VA 22448-5147 


(540) 653 - 1090 (phone at Dahlgren) 
(540) 653 - 8673 (fax at Dahlgren) 


  

  
  
   
     
    

  

    Re:  questions about current NTP
protocol draft
  


  

     country flaguser name
United States		
     2007-04-04 17:09:31
  


  

    

  


  

    That's peer dispersion epsilon, as opposed to root 
dispersion capepsilon.    The text in the graphic shows the 
correct epsilon.

 


Greg Dowd 
gdowd at symmetricom dot com (antispam 
format) 
Symmetricom, 
Inc. 
www.symmetricom.com 
"The current implementation is non-obvious and may need 
to be improved." 




 






From: Odonoghue, Karen F CIV NSWCDD, W13 
[mailto:karen.odonoghuenavy.mil] 
Sent: Wednesday, April 04, 2007 
2:56 PM
To: Greg Dowd; Plunkett, Timothy R CIV NSWCDD, W13; 
ntpwglists.ntp.isc.org
Subject: RE: [ntpwg] questions about current 
NTP protocol draft








I asked Tim to check the 
reformatted xml to make sure nothing got corrupted in the process. 



The equation in question is: 



 


Karen


 


   In the next step the shift register stages are copied to a temporary

   list and the list sorted by increasing delta.  Let i index the stages
   starting with the lowest delta.  If the first tuple epoch t_0 is not
   later than the last valid sample epoch p.t, the routine exits without
   affecting the current peer variables.  Otherwise, let epsilon_i be
   the dispersion of the ith entry, then
                     i=n-1
                     ---     epsilon_i

      capepsilon =         ----------
                      /        (i+1)
                     ---     2
                     i=0

   is the peer dispersion p.disp.  Note the overload of epsilon, whether
   input to the clock filter or output, the meaning should be clear from
   context.






From: 
ntpwg-bounces+karen.odonoghue=navy.millists.ntp.isc.org on behalf of Greg 
Dowd
Sent: Wed 4/4/2007 4:22 PM
To: Plunkett, Timothy R CIV 
NSWCDD, W13; ntpwglists.ntp.isc.org
Subject: Re: [ntpwg] questions 
about current NTP protocol draft






I'm honestly not EXACTLY sure what version is what in the 
xml domain but I'll vote.


 



1) I don't see capepsilon in the non xml version.  Can 
you quote the string or equation here? ; In any case, capepsilon is 
root dispersion.  If the notes or context allows you to determine that the 
variable in question is indeed root dispersion then EPSILON would be correct in 
the latest version.


 



2) Yes, sqrt of the sum of the squares.  



 



 


Greg Dowd 
gdowd at symmetricom dot com (antispam 
format) 
Symmetricom, 
Inc. 
www.symmetricom.com 
"The current implementation is non-obvious and may need 
to be improved." 




 






From: 
ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org 
[mailto:ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org] On Behalf Of 
Plunkett, Timothy R CIV NSWCDD, W13
Sent: Wednesday, April 04, 
2007 2:02 PM
To: ntpwglists.ntp.isc.org
Subject: [ntpwg] 
questions about current NTP protocol draft






I am currently editing the XML version of the latest 
NTPv4 protocol draft.  I noticed the following two things that I was hoping 
that someone could clarify for me.


1.  Should the equation for capepsilon in 
section 10 be for a variable called EPSILON instead?  I know that there has 
been an effort to remove all the "cap" variables and I think this is a 
leftover.


2.  Should the equation for PSI in section 
11.2.3 have a square root function in it?  Seems like PSI should equal SQRT 
[(PSI_s)^2 + (PSI_p)^2].  If preferred I could also raise it to the one 
half power as well.


Thanks, 


Tim 


*********************************************************** 

Timothy R. Plunkett 
NSWC-DD, Code W13 
Building 1500 Room 
A122A 
17214 AVENUE B SUITE 100 

DAHLGREN, VA 22448-5147 


(540) 653 - 1090 (phone at Dahlgren) 
(540) 653 - 8673 (fax at Dahlgren) 



  

  
  
   
     
    

  

    Re:  questions about current NTP
protocol draft
  


  

     user name

     2007-04-04 17:16:51
  


  

    
Greg,

But what I am saying is that 


                     i=n-1
                     ---     epsilon_i
      capepsilon =         ----------
                      /        (i+1)
                     ---     2
                     i=0

should be changed to be instead


                     i=n-1
                     ---     epsilon_i
         EPSILON =         ----------
                      /        (i+1)
                     ---     2
                     i=0
or maybe the capepsilon should only be epsilon, but I am
sure that
"capepsilon" should no longer be there.  There are
no other variables in
the document that start with "cap".  They have
been replaced with an ALL
CAPS version of them.

Tim


***********************************************************
Timothy R. Plunkett
NSWC-DD, Code W13
Building 1500 Room A122A
17214 AVENUE B SUITE 100
DAHLGREN, VA 22448-5147

(540) 653 - 1090 (phone at Dahlgren)
(540) 653 - 8673 (fax at Dahlgren)


-----Original Message-----
From: Greg Dowd [mailto:GDowdsymmetricom.com] 
Sent: Wednesday, April 04, 2007 18:10
To: Odonoghue, Karen F CIV NSWCDD, W13; Plunkett, Timothy R
CIV NSWCDD,
W13; ntpwglists.ntp.isc.org
Subject: RE: [ntpwg] questions about current NTP protocol
draft

That's peer dispersion epsilon, as opposed to root
dispersion
capepsilon.    The text in the graphic shows the correct
epsilon.
 

Greg Dowd 
gdowd at symmetricom dot com (antispam format) 
Symmetricom, Inc. 
www.symmetricom.com 
"The current implementation is non-obvious and may need
to be improved."




 

________________________________

From: Odonoghue, Karen F CIV NSWCDD, W13
[mailto:karen.odonoghuenavy.mil] 
Sent: Wednesday, April 04, 2007 2:56 PM
To: Greg Dowd; Plunkett, Timothy R CIV NSWCDD, W13;
ntpwglists.ntp.isc.org
Subject: RE: [ntpwg] questions about current NTP protocol
draft


I asked Tim to check the reformatted xml to make sure
nothing got
corrupted in the process. 
The equation in question is: 
 
Karen
 
   In the next step the shift register stages are copied to
a temporary
   list and the list sorted by increasing delta.  Let i
index the stages
   starting with the lowest delta.  If the first tuple epoch
t_0 is not
   later than the last valid sample epoch p.t, the routine
exits without
   affecting the current peer variables.  Otherwise, let
epsilon_i be
   the dispersion of the ith entry, then
                     i=n-1
                     ---     epsilon_i
      capepsilon =         ----------
                      /        (i+1)
                     ---     2
                     i=0

   is the peer dispersion p.disp.  Note the overload of
epsilon, whether
   input to the clock filter or output, the meaning should
be clear from
   context.


________________________________

From: ntpwg-bounces+karen.odonoghue=navy.millists.ntp.isc.org on behalf
of Greg Dowd
Sent: Wed 4/4/2007 4:22 PM
To: Plunkett, Timothy R CIV NSWCDD, W13; ntpwglists.ntp.isc.org
Subject: Re: [ntpwg] questions about current NTP protocol
draft


I'm honestly not EXACTLY sure what version is what in the
xml domain but
I'll vote.
 
1) I don't see capepsilon in the non xml version.  Can you
quote the
string or equation here?  In any case, capepsilon is root
dispersion.
If the notes or context allows you to determine that the
variable in
question is indeed root dispersion then EPSILON would be
correct in the
latest version.
 
2) Yes, sqrt of the sum of the squares.  
 
 

Greg Dowd 
gdowd at symmetricom dot com (antispam format) 
Symmetricom, Inc. 
www.symmetricom.com 
"The current implementation is non-obvious and may need
to be improved."




 


________________________________

From: ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org
[mailto:ntpwg-bounces+gdowd=symmetricom.comlists.ntp.isc.org] On Behalf
Of Plunkett, Timothy R CIV NSWCDD, W13
Sent: Wednesday, April 04, 2007 2:02 PM
To: ntpwglists.ntp.isc.org
Subject: [ntpwg] questions about current NTP protocol draft



I am currently editing the XML version of the latest NTPv4
protocol
draft.  I noticed the following two things that I was hoping
that
someone could clarify for me.

1.  Should the equation for capepsilon in section 10 be for
a variable
called EPSILON instead?  I know that there has been an
effort to remove
all the "cap" variables and I think this is a
leftover.

2.  Should the equation for PSI in section 11.2.3 have a
square root
function in it?  Seems like PSI should equal SQRT [(PSI_s)^2
+
(PSI_p)^2].  If preferred I could also raise it to the one
half power as
well.

Thanks, 

Tim 

***********************************************************

Timothy R. Plunkett 
NSWC-DD, Code W13 
Building 1500 Room A122A 
17214 AVENUE B SUITE 100 
DAHLGREN, VA 22448-5147 

(540) 653 - 1090 (phone at Dahlgren) 
(540) 653 - 8673 (fax at Dahlgren) 


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ntpwg mailing list
ntpwglists.ntp.isc.org
http
s://lists.ntp.isc.org/mailman/listinfo/ntpwg



  


  

    
  

  
  
   
     
    






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