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Re: Proposed Resolution of Issues [1-37]
Fred Baker wrote:
So it helps in renumbering by not needing to be renumbered. Same would
be true if it just happened to be in a different global prefix that
happened to not need renumbering. I don't think that is an argument for
or against ULAs, or even an argument about renumbering. It is a
statement that things that are not at the moment up for renumbering
probably don't have to be thought about when renumbering.
It seems to me that if one is going to say anything on the topic here,
one might say that a step one might take early in the game of
renumbering is to scan the DNS database for names that have more than
one address, one of which is in the prefix to be renumbered. In any
such case, one can instantly remove the affected address from the name,
and all future DNS accesses will be from another prefix (which may be a
ULA). When one adds the new prefix to DNS, one may include these names
in doing so. Doing so early will limit the impact of all the other
steps on the utility of the systems, as the prefix being renumbered
will not be in use for that system.
ULAs are a special case of that statement, and only apply to local
systems.
That's true. Because IPv6 networks may have multiple simultaneous prefixes
as a matter of course, that check always seems to be needed.
And by the way, the above comment doesn't simplify
renumbering. It adds a step (one which is redundant with a later step)
and requires memory in some form of what names were affected and
therefore have to be restored. It makes renumbering more complex.
It's the observation that a site may have N prefixes only some of
which are being renumbered that adds complexity, I think. In this respect
I don't see that a ULA prefix is any different from an RIR-allocated
prefix that is only used internally - i.e. I see no architectural
change here. (This is another face of the assertion that ULAs behave
like global addresses.)
Brian
On Sep 7, 2005, at 6:48 AM, Brian E Carpenter wrote:
Sometime in the past, I said:
If ULAs simplify the procedure of renumbering a network without a
flag day, then there should be several places in the document where
a few sentences of the following form can be added.
"if the old prefix..." or "if the new prefix..."
"is a ULA prefix then"
"...this step may be skipped" or "...this step may be simplified
<in this way>"
"and it still allows you to renumber a network without a flag day
for <this> reason."
Present me with those sentences, and I will include them.
I don't think any of that applies. My take is that ULAs have the
advantage during a renumbering exercise of providing business
continuity for *internal* operations - your printers, for example,
can have ULAs and are untouched (and their DNS entries are untouched)
during the renumbering process. Your internal SMTP system can keep
operating without any change to internal DNS. Etc. So it does take a
number of hosts off the renumbering list - exactly those hosts that
have no external visibility.