Right, but what I am trying to get at is the wording "obtain the current time of day" in 64-bit NTP format [NTP]. The phrase "current" implies some degree of accuracy with regard to the notion of a wallclock (absolute date and time) which is seconds relative to 0h UTC on Jan. 1,1900.
So, if a client has no notion of a wallclock, couldn't it set the current time of day in 64-bit NTP format to zero? Or maybe it could simply use a "system-specific" clock such as "system uptime". I haven't done any simulations, but this would certainly increase the probability of a collision (at least for locally assigned global IDs) ... granted, there is probably still a very low probability of non-unique locally assigned global IDs being generated by the algorithm. Even if the client has a notion of a wallclock, the accuracy may be limited to far less than the resolution that the 64-bit NTP format is capable of representing ... so more zeros perhaps for the 32 bits to the right of the decimal? So if the algorithm is dependent upon "current time of day", I should think that we would want some statement included in the document to the effect that (1) access to a wallclock or not (2) running the Network Time Protocol not being required (3) other time sources, or none at all, may be used, etc. Pete -----Original Message----- From: Brian E Carpenter [mailto:[EMAIL PROTECTED] Sent: Thursday, August 07, 2003 7:01 AM To: [EMAIL PROTECTED] Subject: Re: I-D ACTION:draft-hinden-ipv6-global-local-addr-01.txt > Peter Barany wrote: > > Hi, > > Two questions about this I-D: > > (1) In Section 3.2.3 "Sample Code for Pseudo-Random Global ID Algorithm", step (1) of the algorithm states: > "Obtain the current time of day in 64-bit NTP format (NTP)" > Question: Would it be possible to have the I-D specify that "how the current time of day is obtained is beyond the scope of > this document"? What is specified is the format, not the source. It's necessary to specify a format in order to specify an algorithm. - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - Brian E Carpenter Distinguished Engineer, Internet Standards & Technology, IBM NEW ADDRESS <[EMAIL PROTECTED]> PLEASE UPDATE ADDRESS BOOK -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] -------------------------------------------------------------------- -------------------------------------------------------------------- IETF IPng Working Group Mailing List IPng Home Page: http://playground.sun.com/ipng FTP archive: ftp://playground.sun.com/pub/ipng Direct all administrative requests to [EMAIL PROTECTED] --------------------------------------------------------------------
