Mark explained this idea to me in Pittsburgh and once I finally
understood it, it seemed extremely useful at a very low cost.
Essentially, you'd leave the A6 records for the shortest global
prefixes alone, but put site-local and, if you wish, link-local
prefixes into your DNS, putting a DNS name of your choice into the
final A6 record with prefix length=0. Example:
$ORIGIN example.com.
myhost A6 64 ::1234:5678:9abc:def0 subnet-one.ip6
subnet-one.ip6 A6 48 0:0:0:1:: ip6
A6 0 fe80:0:0:: link-one
ip6 A6 48 0::0 example-com-usa.ip6.my-isp.net.
A6 0 fec0:0:0:: usa-hq
yourhost A6 64 ::0246:8ace:1357:9bdf subnet-two.ip6
subnet-two.ip6 A6 48 0:0:0:2:: ip6
A6 0 fe80:0:0:: link-two
herhost A6 64 ::048c:159d:26ae:37bf subnet-eins.ip6
subnet-eins.ip6 A6 48 0:0:0:1 ip6de
A6 0 fe80:0:0:: link-eins
ip6de A6 48 0::0 example-com-de.ip6.andere-isp.de.
A6 0 fec0:0:0:: de-site
usa-hq TXT "There need not be any record at this label."
de-hq TXT "There need not be any record at this label either."
So now if myhost looks up yourhost it gets a site-local address as
well as a global address. The last RR of yourhost's site-local A6
chain has the same "prefix name" field as the last RR of myhost's
site-local A6 chain, so myhost can conclude that yourhost is on the
same site. Similarly, it can conclude that yourhost is not on the
same link as my host, and that herhost is not on the same link or
site.
> Currently A6 records w/ prefix 0 do not have a prefix
> domain name. Redefining A6 records with prefix 0 to
> have a domain name and to use this name as a site /
> link local identifier is still possible at this point
> in time.
>
> Doing this would provide a mechanism to identify which
> of a number of addresses you which to use.
Today I thought of one possible simplification. Couldn't the *owner
name* of the final A6 record in a chain be used for the same purpose?
______________________________________________________________________________
Matt Crawford [EMAIL PROTECTED] Fermilab
"A5.1.5.2.7.1. Remove all classified and CCI boards from the COMSEC equipment,
thoroughly smash them with a hammer or an ax, and scatter the pieces."
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