Re: why 0xFFFE is used in the modified EUI-64 format

Jinmei,

On Jan 18, 2006, at 8:40 PM, JINMEI Tatuya / 神明達哉 wrote:

>>>>>> On Wed, 18 Jan 2006 09:54:51 -0800,
>>>>>> Bob Hinden <bob.hinden@nokia.com> said:
>
>> Here is the text I propose to send to the RFC-Editor to resolve the
>> issue.  Take a look and let me know it is is OK.
>
> I personally support this text with one very minor nit:
>
>> Add:
>
>> Add to the end of the appendix:
>
>>     Note: [EUI-64] actually defines 0xFF and 0xFF as the bits to be
>>     inserted to create an IEEE EUI-64 identifier from an IEEE MAC-48
>>     identifier.  The 0xFF and 0xFE values are used when starting  
>> with an
>>     IEEE EUI-48 identifier.  The incorrect value was used in earlier
>>     versions of the specification due to an misunderstanding about  
>> the
>
> s/an misunderstanding/a misunderstanding/

Thanks, I will fix this.

>>     differences between IEEE MAC-48 and EUI-48 identifiers.
>
>>     This document purposely continues the use of 0xFF and 0xFE
>>     because it meets
>>     the requirements for IPv6 interface identifiers, specifically  
>> that
>>     they must be unique on the link, and that it doesn't cause any
>>     problems in practice.  If in the future, a new link type is  
>> invented
>>     that uses IEEE EUI-48 and MAC-48 identifiers on the same link,  
>> the
>>     0xFF and 0xFF values could be used to convert the EUI-48  
>> identifiers
>>     for use as IPv6 interface identifiers to avoid any potential for
>>     duplicate interface identifiers.
>
> I said 'personally' because it may be controversial to mention the
> possibility of the future use of 0xFFFF at this stage (i.e., it may be
> beyond the level of 'clarification').  But if the IESG accepts the
> description (or the RFC editor agrees this is minor enough), I'm happy
> with that.

It's only a note at the end of an appendix, but I wouldn't object to  
removing the last sentence if others are troubled by it.  The intent  
was to provide some advice to someone writing an IPv6 over <foo>  
specification.

Thanks,
Bob

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