[Nsi-wg] Immediate/Advance reservation (Re: NSI conf call minutes)

[Tomohiro Kudoh]

Hi Jeroen,

There is a problem for inter-network connection. During the discussions
in some calls, the problem of synchronizing networks (managed by
different NSAs) was discussed.

If you use the "now" type request for inter-network connection (without
complicated coordination), the actual provisioning time of networks may
be different. Moreover, some networks may provision resources before
some other networks reply to the request, and such networks might deny
the request. In this case, only some parts of inter-network connection
will be provisioned.

The guard time is one of the simple solutions to solve this problem. I
understand there can be multiple ways to cope with this, but all of them
will introduce some complication to some part (note that we decided not
to use 2PC for the v1.0). This is a design choice matter.

Regards,

Tomohiro


On Thu, 08 Apr 2010 09:27:59 +0200
Jeroen van der Ham <vdham at uva.nl> wrote:

> On 07/04/2010 15:02, Tomohiro Kudoh wrote:
> > If a requester wants resources to be provisioned as soon as possible, it
> > can set the start time parameter in a advance request to:
> > (current time + guard time + a certain time required for message
> > delivery).
> > 
> > In this way, immediate provisioning can be requested by an advance
> > reservation request.
> 
> The procedure above seems overly complicated and if I really am pressed
> for time, and I miscalculate the (current time + guard time + delivery
> time) by a few seconds. Denying the request means that I have to do it
> all over again, making me even more pressed for time.
> 
> Why not keep things simple and always interpret a start time in the past
> as "now" ? (provided the end-time is in the future too)
> Would there be any problems associated with that?
> 
> Jeroen.