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Re: Proposed Resolution of Issues [1-37]

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. 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.

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.