[ntp:questions] Re: Philosophical question about strata

Richard B. Gilbert rgilbert88 at comcast.net
Fri Oct 7 17:03:42 UTC 2005


Lee Sailer wrote:

>I had this thought about strata and I am hoping someone might have some
>ideas to contribute.
>
>Suppose you have two ntp clients that get their time from multiple
>strata 1 servers.  They should be very accurate statum 2 servers as a
>result.
>  
>
Should!  Probably will be.

>Now later, you are configuring a new client, and for some reason you
>have a choice.  You can use one of the stratum 1 servers, or the
>stratum 2 server.  (I know, make another choice.  This is a theoretical
>question, ok?)
>
>It seems to me that the right choice is the stratum 2 server.  Am I
>wrong?
>
>  
>
You are not wrong!   Most public stratum 1 servers are stretched to 
nearly the breaking point!   EVERYBODY wants to use a stratum 1 
server.   Now if you are talking about using a private stratum 1 server 
under your ownership and control, or if you would be using it with the 
explicit and voluntary consent of the owner, then feel free.

>However, if you configure this new client so that it uses one stratum 1
>the stratum 2, I think the algorithm will choose the stratum 1.  Again,
>am I wrong?
>
>  
>
Again you are not wrong.   Lower stratum wins every time.  (Well almost....)

>Basically, my thought is that it is possible for a stratum 2 source to
>be better than a stratum 1 source, and likewise for a stratum n source
>to be better than a stratum m source, where n > m.
>
>  
>
You are right.   Stratum 2 servers tend to be less heavily loaded, tend 
to respond more quickly, and tend to have a lower round trip delay if 
you pick servers close to  you.   There are a lot more stratum 2 servers 
to choose from.   Some of them can actually be better than a stratum 1 
server; a server using an HF receiver to synch to WWV or a VLF receiver 
to synchronize to WWVB is technically stratum 1 but the vagaries of 
radio propagation can cause them to have poorer quality time than a 
stratum 2 server synchronized to a stratum 1 server using GPS.   I 
operate two stratum 1 servers in my home; one GPS and one WWV.   The GPS 
server works very well and compares well with the best public stratum 1 
servers.    The WWV synched server can be within a millisecond or two if 
radio propagation conditions are favorable or off by twenty to forty 
milliseconds when conditions are not favorable.

>Comments welcome.  No flames please.
>
>Lee
>Flamed online since 1977
>
>  
>




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