Subject: Random algorithm in draft-ietf-ipv6-unique-local-addr-00.txt

From: Brian Haberman <[email-masked]>
Date: Thu, 28 Aug 2003 08:27:21 -0400

There have been several comments on eliminating the
user input portion of the random selection algorithm.
This would, primarily, provide the capability to
automate the prefix generation process.  After assessing
issues with this, I have two possible proposals:

1. Re-use the random ID process defined in Appendix A.6
   in RFC 1889.  That algorithm derives a 32-bit number
   from the system clock, system name, process ID, and
   several other system-related IDs.  It would have to
   be modified slightly to provide a 40-bit value.

2. Replace the user-supplied birthday value with a system
   derived value (EUI has been suggested).  The system
   clock would still be utilized as a portion of the input
   to MD5.

It should be noted that #1 will return the same value on
repeated calls until the system clock changes or a different
value is passed in as a parameter.

At this point, my preference is for #1, since it has been
tested as a part of RTCP and the probability function is
well-defined in the rfc.

If others have differing opinions, let me know.

Thanks,
Brian H.

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