Re: [mpls] Last Call: <draft-ietf-mpls-spl-terminology-03.txt> (Special Purpose Label terminology) to Informational RFC

[Stewart Bryant <[e-mail]>]

> On 24 Aug 2020, at 11:02, tom petch <[e-mail]> wrote:
> 
> On 23/08/2020 21:47, Adrian Farrel wrote:
>> Hi Tom,
>> 
>> You're right (a condition that must be scarily familiar for you).
>> 
>> Probably...
>> 
>> OLD
>>    o  Collectively, the two ranges are known as Special Purpose Labels
>>       (SPL).
>> 
>>    o  The special purpose labels from the lower range will be called
>>       Base Special Purpose Labels (bSPL).
>> 
>>    o  The special purpose labels from the higher range will be called
>>       Extended Special Purpose Labels (eSPL).
>> NEW
>>    o  Collectively, the two ranges (0-15, and 16-1048575) are known
>>        as Special Purpose Labels (SPL).
>> 
>>    o  The special purpose labels from the lower range (0-15) will be
>>        called Base Special Purpose Labels (bSPL).
>> 
>>    o  The special purpose labels from the higher range (16-1048575)
>>         will be called Extended Special Purpose Labels (eSPL).  The
>>         reserved values 0-15 from the 'Extended Special-Purpose MPLS
>>         Label Values' registry do not need a name as they can never be
>>         used.
>> END
> 
> Yes, clearer.
> 
> Perhaps
> "       The
>    reserved values 0-15 from the 'Extended Special-Purpose MPLS
>    Label Values' registry do not need a name as they are not available for allocation. "
> to tie in with the wording of IANA.  They SHOULD NOT or MUST NOT be used but I can see some independent-minded organisation deciding that because noone else will ever use them then they can and they will so I think 'can never be used' is not quite right.  They can never be allocated so we do not need an identifier for them, which is what I am wanting to express.
> 
> I note that this is Informational and so RFC2119 language is best avoided.
> 
> Tom Petch


There is no history in the Internet of anyone ever treating a "never to be used" value as an opportunity :) 

How about:

> "       The
>    reserved values 0-15 from the 'Extended Special-Purpose MPLS
>    Label Values' registry do not need a name as they MUST NOT be used “

Alternatively:

> "       The
>    reserved values 0-15 from the 'Extended Special-Purpose MPLS
>    Label Values’ registry are called the MUST NOT USE range range as they MUST NOT be used. "


- Stewart