[ntp:questions] Re: Yet Another Isolated Network Question

Richard B. Gilbert rgilbert88 at comcast.net
Sat Dec 18 21:28:47 UTC 2004


Bruce Baumgart wrote:

>Richard B. Gilbert wrote in news:KNSdnZbxio44o17cRVn-1g at comcast.com:
>
>  
>
>>Bruce Baumgart wrote:
>>    
>>
>>>Richard B. Gilbert wrote:
>>>      
>>>
>>>>Bruce Baumgart wrote:
>>>>        
>>>>
>
><MISC SNIPPAGE>
>
>  
>
>>Your local server should follow the remote server.    It the remote 
>>server is not synchronized to an external clock of some sort, someone 
>>will have to correct it manually from time to time.
>>    
>>
>
>Yep.  Not my problem, just bothers me aesthetically.
>
>  
>
>>#
>># Declare the local clock to be the clock of last resort.
>># It will be used to serve time in the absence of any other.
>>#
>>server 127.127.1.0
>>fudge 127.127.1.0 stratum 10
>># 
>>In your particular case setting the local clock to stratum ten may not 
>>be necessary but it will do no harm and is good practice.  The high 
>>stratum should convince just about anybody that it's not a desirable 
>>clock to synchronize with if there is any other choice.
>>
>>    
>>
>
>A curiousity question.  If you don't fudge the local clock, it defaults 
>to stratum-5.  Every time anybody shows the local clock server statement, 
>they say to fudge it to 10. Is there any case where a local clock should 
>be left a 5?  Why not default it to 10?  
>
>
>  
>
You'd have to ask the designers.  If you hadn't mentioned it, I wouldn't 
have tried it and I would have predicted that the stratum would be one 
greater than that of the server it was synchronized with.  But, I just 
added the local clock as a server without setting the stratum and, sure 
enough, it shows up as five.

Stratum 5 could show up in a normal hierarchy.  Say an enterprise 
synchronizes it's server to a group of stratum 2 servers on the 
internet.  That server becomes stratum 3.  Anything that synchronizes to 
it becomes stratum 4.   Branch offices synchronize their servers to the 
head office and their clients become stratum 5.  Even though stratum 
could go as high as 15, 10 is close enough to the bottom of the barrel 
that nobody will use it if there's any other choice.

I suspect that, if it were not for backward compatibility,  modern 
versions of ntp would use a three bit stratum field.  Delays and errors 
accumulate quickly enough that stratum seven would be essentially 
clueless as to what time it is!



More information about the questions mailing list