[Nsi-wg] New state machine with two phase reserve and modify

[Jerry Sobieski]

On 7/6/12 1:23 AM, Chin Guok wrote:
> Hi Henrik,
> On 7/5/12 2:08 AM, Henrik Thostrup Jensen wrote:
>> On Wed, 4 Jul 2012, Chin Guok wrote:
>>
>>> Actually the IDCP has a single phase reservation workflow.
>>
>> I stand corrected.
>>
>>> That is the reason why it explicitly only supports the chain model.
>>
>> (going off topic here)
>>
>> Mmm... I do not see why that should restrict it to chain model. Sure 
>> tree will be somewhat oppertunistic, but as long as one can cancel 
>> the connections I do not see thep roblem. Could you eloborate?
> Yes, the cancel operation can accomplish this for a tree, however we 
> chose to go the easier route and model it after RSVP.
Remember:  The Tree model does not imply "parallel" Reserve() requests 
in time domain.   It simply means that the an RA is able to make 
reservation requests directly to downstream PAs.  Such a tree RA can 
still reserve each segment of the path sequentially, proceeding from 
source to destination issuing a Reservation requests to each domain.  
Once each domain returns a confirmation, the RA moves to the next 
domain.    This "sequential tree" process resolves dependencies at the 
reservation stage, but is unnecessary for the Provision process since 
the resources have already been confirmed.   At the Provision stage, 
parallel in time provisioning can easily be performed.  This subtle 
distinction sometimes creates confusion.

A sequential Tree process is in effect a Chain path finding process, but 
allows the RA to control the inter-domain path and the PAs to 
authenticate the RAs more directly.

Regards
Jerry