Re: [dhcwg] Second dhc wg last call on "Time Protocol Servers and Time Offset Options for IPv6 DHCP"

John Schnizlein wrote:
> The reason Dynamic Host Configuration calls these things options is
> that hosts can choose which to request.  Assuming you are correct that
> "general purpose OSes" would prefer to obtain and use an index into a
> historic database of timezone information, an option for that should
> be made available.
For purpose of clarity, when I wrote "general purpose OSes" I meant
Windows, MacOS, Linux, Solaris, AIX, and some embedded Java stacks (I
can't speak to all of them).  I have not reviewed VXworks and I am aware
that some small devices don't include ANY support for timezones (at all)
and cannot understand the difference between wall clock and UTC.
>
> However, insisting on deprecating an option that some special-purpose
> operating systems use, rather than fixing a problem with changing the
> offset twice a year, ignores the reality that the other option has
> utility for different hosts on the Internet.  Why not let hosts that
> use the existing Time Offset option (2) continue to use it, and fix
> the problem with it that you identified?

There are two reasons to deprecate something.  One is when it is not
used, and the other is when it should not be used.  For example, SNMPv1
is plenty used but deprecated in favor of SNMPv3.  Here I suggest
something similar.  The time offset option is broken, and when used as
directed requires substantial operational overhead to even attempt to
maintain correct time through a DST transition for those OSes that code
to it.  And so it seems to me that the appropriate approach is to
provide an approach that works more generally, requires less special
code, has a lower operational overhead, and most importantly produces
correct local time.
>
> Making these separate options enables hosts to use the the Parameter
> Request List option (55) to indicate their preference to the DHCP server.
The forthcoming draft -01 (it's in the internet-drafts queue) breaks the
previous suboptions out into separate options, based on this group's
wishes.  I presume it could then be used with option 55?

Eliot

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