[ntp:questions] Re: an example of a negative RootDelay, please...

Morpheus spam at world.com
Fri Aug 8 19:59:44 UTC 2003


> The root delay format is described on p. 51 of RFC-1305 as I'm sure you
> have seen.

yes, i have...

> As in almost everything Internet, this and other NTP packet
> variables are in twos-complement representation and big-endian network
> byte order. That completely describes both positive and negative values
> except for scaling. The decimal point for the root delay and root
> dispersion is between bits 15 and 16. Once you understand how
> twos-complement arithmetic works, the answer to your question is obvious.

i know 2-complement arithmetic for integers or floating-point numbers, but
not in fixed point arithmetic... let me take some example: -1,1 in
RootDelay format for integer part we got  '255 255' (in byte) but for
fractional part? something like '128 0'? (maybe it 0,2..) or something
else? i try search something but i can't find some stuff that let me
understand... you may help perhaps....

> Negative values for roundtrip delay and by implication root delay are in
> principle possible, but very rare.

thus they not impossible, so i have to understand how they work...

bye and thanks again

More information about the questions mailing list