[Nsi-wg] time issue

[John Vollbrecht]

Hello all -

Jerry and I had a discussion last week about the time issue.  I think we developed a useful approach.

The idea is to define two times, which I think we all agree exist.

1) available time - time a connection is available to the application to communicate between devices
2) resource time - time a resource is reserved to support available time

To further define these -

Available time 
- requested by the user for its application
- provided by the network.  

resource time 
- time a resource is allocated to a connection
- includes setup and teardown time, if any
- is time in reservation calendar for resource

Available time requested cannot be provided exactly by network because it cannot predict exactly length of setup and take down.  I believe we all agree with this.  
Therefore provided available time can at best approximate requested available time.

We agreed that when a user requests automatic start connection it would request available time and the provider would schedule resource time to get as close as possible.
When a request is for user initiated connection the time would be for reserved time, and the user initiation can start anytime after the reserved time.  Available time depends on setup and take down times of equipment.

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I think we agreed on the above definitions.  The definition of time seem useful in discussing what goes in connection service messages.  We also talked about some possible implications of this.

The difference between available and resource time is setup and takedown time.  While it is impossible to be sure exactly how long they will be, it may be possible to define something statistical.  For example setup takes an average of 17 sec with std deviation of N.  If this is can be defined for the resource, then one can make a prediction about when a connection will be available with a degree of confidence.  

For example this would allow one to request an automatic connection, for example, at 5pm and have it available 99% of the time.  If the average setup time is 17 seconds and I add 10 seconds to be 99% sure, then the service would initiate the connection at 5:00:00 - 0:00:25, or 4:59:35.

We talked about including this "setup requirement" in the connection service definition of and NSA, and by implication including this in requests and replies.  I think this is worth talking about in the group.

John