On 11/29/05, Sam Hartman <hartmans-ietf(_at_)mit(_dot_)edu> wrote:
However the update behavior if you add agility is more complicated.
I think this is the key to the objections, and deserves a lot of consideration.
Adding agility would presumably require either
a) Requiring that all consumers of DHCID records are configured to use
the same hash algorithm, or
b) Requiring that the DHCID record encodes the hash and possibly
permitting multiple hashes for the same data.
The problem with b) is that it changes the UPDATE process - right now,
or with a), the DHCP server sends an UPDATE to the DNS server saying
"If this name exists, and if the DHCID record matches this string,
then delete the existing records (and add the new record(s)"
(draft-ietf-dhc-ddns-resolution section 6.3.2). This is an atomic
operation - the query, match and update.
If the DHCP server doing the UPDATE doesn't know what hash to use a
priori, it has to query the existing record to find out what hash to
use, changing this to a multi-step process with possible associated
race conditions (I think you can eliminate them, but you have to be
careful). This is almost certainly what is getting the pushback.
Bill
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