Subject: RE: I-D ACTION:draft-ietf-send-cga-01.txt

From: "Tuomas Aura" <[email-masked]>
Date: Fri, 22 Aug 2003 02:10:36 -0700

There was some discussion on CGA and DAD on this list in July. 

There are arguments both for and against DAD.
CGA addresses have at least 59 bits of entropy and accidental 
collisions are very unlikely. On the other hand, 
implementation and configuration errors might lead to collisions. 

But the "to DAD or not to DAD" question is not specific 
to CGA addresses. Exactly the same arguments apply to 
RFC-3041 addresses (which have 62 bits of entropy if generated 
with a good PRNG; slightly less if generated as specified in 
RFC 3041). EUI-64 identifiers are, in theory, unique. 
However, the widespread practice of cloning MAC addresses makes
occasional collisions between two EUI-64s quite likely. 

Conclusion:
The DAD question is not specific to CGA addresses.
Therefore, it should be discusses separately from SEND. 
For the time being, we assume that DAD is required.

Tuomas

> -----Original Message-----
> From: Soohong Daniel Park [mailto:[email-masked]]
> Sent: 22 August 2003 09:19
> To: [email-masked]
> Cc: Tuomas Aura
> Subject: RE: I-D ACTION:draft-ietf-send-cga-01.txt
> 
> Hi SEND
> 
> Simple questions
> 
> If we use a cga mechanism on the all host, don't we
> need a DAD procedure to verify the address uniqueness ?
> or not related ?
> 
> Thanks
> 
> Daniel (Soohong Daniel Park)
> Mobile Platform Lab,SAMSUNG Electronics
> 
> 
> 
> 

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