[ntp:questions] Re: Asymmetric Network and Delay Questions.

Danny Mayer mayer at gis.net
Fri Jul 15 02:12:44 UTC 2005


Richard B. Gilbert wrote:
> Brad Knowles wrote:
> 
>> At 10:46 AM +0200 2005-07-14, Brad Knowles wrote:
>>
>>>     If there is significant asymmetry, you can pretty much throw out 
>>> all the
>>> NTP algorithms, because you are violating one of the most basic 
>>> assumptions.
>>
>>
>>
>>     I should mention one other thing -- if you use a broadcast NTP 
>> service, then you don't have to worry about asymmetry. The clients 
>> just sit and passively listen to the server broadcasting the time, and 
>> then apply what they receive.
>>
> I don't believe this is completely correct.  Doesn't a broadcast client 
> exchanges packets with the server when it initializes, in order to 
> determine the network delay?

Normally yes. I think the novolley option eliminates that but then you 
are stuck not knowing certain important pieces of information and if you 
want authentication you MUST exchange packets with the server.

Danny

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