Re: RAO for IPv4

I've got an architectural issue with any protocol having specific  
values in the RAO.  In general, that's
a poor approach, as it will (in the long term) lead to multiple  
protocols piggybacking on RAO.  Why not simply allocate another  
option on a per-protocol basis?

This also has the nice side effect that it ensures that things are  
backward compatible.

Tony


On Oct 24, 2007, at 12:56 PM, Jukka MJ Manner wrote:

>
> Hi Thomas, Bob,
>
> Thanks for the discussion.
>
> The specific application that needs (well, to be precise, would  
> greatly
> benefit) RAO is NSIS. That is why NSIS ML is CC:d.
>
> Moreover, the RSVP spec talks about multiple RAO values, but lets  
> it open
> as to whether IPv4 should also have those, not just IPv6.
>
> RFC2113 also says that "The semantics of other values in the Value  
> field
> are for further study."
>
> The point is, is it time to study those "other values" further? At  
> least
> GIST and the whole NSIS framework would greatly benefit from more  
> values
> than just "0" for IPv4, and these values should be the same for  
> IPv6 also,
> for simplified implementations.
>
> There is a lot of discussions about RAO in the GIST spec, e.g.,  
> Sections
> 4.3.1., 4.3.4., 5.3.2.1., 5.3.2.2., 6. IANA Considerations and  
> Appendix C:
>
> http://tools.ietf.org/wg/nsis/draft-ietf-nsis-ntlp/
>
>
> Regards,
> Jukka
>
>
> On Wed, 24 Oct 2007, Thomas Narten wrote:
>
>> Bob Hinden and I had some further offlist discussion about this.
>>
>> My understanding is that the IPv4 RA option is very basic. It says
>> "look at this packet". The option itself doesn't contain any
>> additional information or "hint" as to what to look for or what the
>> packet contains.
>>
>> The semantics of the IPv6 router alert option are different. The  
>> value
>> itself is used to convey additional "hints" about processing.
>>
>> My sense is that the semantics of the IPv4 and IPv6 Router Alert
>> option are sufficiently different that sharing the name space just
>> doesn't make any sense.
>>
>> That is, the  ID says:
>>
>>     This document proposes the creation of a new IANA registry for
>>     managing IPv4 Router Alert Option Values.  In conjunction with
>>     this, it also proposes an update to the way in which IPv6 Router
>>     Alert Option Values are assigned in the existing IANA registry.
>>
>> But there are no defined IPv4 Router Alert Option values (other than
>> zero), and it would be inappropriate to change the semantics of any
>> existing usages (too late for that) and it would also be  
>> inappropriate
>> to consider doing this in the absense of a specific new application
>> that would make use of a new value. This document does not propose
>> such a new usage.
>>
>> Hence, at this point, I'm opposed to the actions called for in the
>> document.
>>
>> Thomas
>>
>
>
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