RE: Comments: draft-savola-v6ops-transarch-01.txt

[m.mackay@lancaster.ac.uk]

Hi, 
Also see general comments at end...


Specific Comments
-----------------


   However, the big picture of the transition seems not to have been 
   discussed sufficiently.  Therefore, different people have different
   assumptions on the process, which makes planning the transition 
   architecture very difficult: indeed, it seems that there is a lack of 
   architecture in the transition process.

>>
>> might it be useful to discuss these assumptions before moving on to 
>> the architecture...
>>



2.1. General Principles

   General principles which should be carefully considered when
   architecturing the transition include at least:

     o security

     o simplicity

     o robustness

>>
>> How about introducing the idea of service provisioning here,
>> not sure if it would count as a general principle
>>   Services to be deployed
>>   Behaviour/performance expected
>>



2.2.1. Mechanisms, Deployment Models, and Services

   When forming a transition architecture, there are typically different
   building blocks to be used, from different classes, including:

   Mechanisms:
     o Providing IPv6 connectivity
     o Protocol translation
     o Application-specific protocol interoperability (ie. ALG or proxy)

   Deployment models for IP nodes:
     o IPv4-only
     o Dual-stack with only IPv4 connectivity
     o Dual-stack w/ IPv4/6 connectivity
     o Dual-stack with only IPv6 connectivity
     o IPv6-only

   And services:
     o IPv4-only
     o Separate IPv4 and IPv6
     o IPv4/6
     o IPv6-only

>>
>> Might be good to include some more discussion of the 'starting point' of 
>> the transitioning, e.g.  IPv4 w/wo NAT, dual stack (various flavours) or 
>> new (IPv6 only?)
>>



2.3. Transition Mechanism Deployment Considerations

   There are a few very important questions which must be addressed in
   the cases where a transition mechanism deployment is deemed
   necessary.  For example:

     o if I deploy IPv6-only service, whose burden is it to enable its
       use by all clients I wish to make it accessible to?

     o if I deploy IPv6-only nodes, or dual-stack nodes with only IPv6
       connectivity, whose burden is it to enable them to access all the
       services they want?

     o how much easier would it be to go for dual-stack approach
       instead?

>>
>> Definitely, I think the idea of discussing responsibility for the 
>> provisioning of transitioning is important...
>>


I think this is a good draft and something that should be discussed here sooner rather than later, however it?s perhaps a bit too general at this stage and doesn't actually specify an architecture as much as put forward some useful guidelines. 

It would be great to get more discussion of the 'assumptions' at the start of the document highlighting the main points of contention/discussion to help provide some clarification.

Another point is that while now it is probably best to deploy dual stack with limited IPv6, it might be an idea to outline how this is likely to change in the future. 

Just some thoughts I had, hope this helps.
Michael