Subject: WG Action - 1 week to discuss [LL24] Weaken the PRN generated address requirement from MUST to MAY

From: Erik Guttman <[email-masked]>
Date: Thu, 27 Feb 2003 13:58:56 +0100 (CET)

This issue will be discussed for the next week, ending March 6, 2003.
We will reach a decision whether to accept or reject it at that time.
Please post your response to the zeroconf list.

Description of Issue  Weaken the PRN generated address requirement from
MUST to MAY    
Submitter Name  Subrata Goswami    
Submitter Email Address  [email-masked]    
Date first submitted  11 Feb 03
Reference       
Comment Type ['T'echnical | 'E'ditorial]  T   
Priority ['S' Must fix | '1' Should fix | '2' May fix ]  2    
Section 2.1
Rationale/Explanation of issue: 

The algorithm that a LL node uses to determine its LL address does not
need to be always PRN based, as ARP can be used validate if it is unique
in the Link. 

Lengthy description of problem: 

Section 2.1 says,

"When a host wishes to configure a link-local address, it selects
an address using a pseudo-random number generator with a uniform
distribution in the range from 169.254.1.0 to 169.254.254.255."

".. The pseudo-random number generation algorithm MUST be chosen so that
different hosts do not generate the same sequence of numbers."

Here text should be changed to indicted that the node can use other
means
to select a LL address than PRN, but has to varify uniqueness by ARPing
before it intends to use that adderess on a link the first time
(or after absence). 

Requested Change: 

".. The pseudo-random number generation algorithm MAY be chosen so that
different hosts do not generate the same sequence of numbers."

---

From: Robert Elz <[email-masked]>
Date: Thu, 27 Feb 2003 21:20:27 +0700

Reject LL24.

I suspect that the intent here is more along the lines of "I could use
real random numbers, rather than fake ones", but it reads as if "I should
be able to use 1 2 3 ... as my sequence" is what is being suggested.

Certainly there's a point here, there's no need for the random numbers used
to be pseudo-random, real random numbers would work just as well.

But I don't think anyone with real random numbers available, and who
has the desire to use them will be very worried by the requirement that
a pseudo-random set of numbers be used (it isn't as if it is justified by
some requirement that the sequence be repeatable).   Just leaving the text
as it is is good enough for now.

kre

ps: if I'm wrong, and the intent really was to allow 1 2 3 or 2 4 6
or similar as the number sequence, then this would be too silly to even
bother commenting on - a PRNG is just a multiply/add sequence, there's
no conceivable reason not to do at least that.