[Planetlab-devel] opening up GetSliceTicket()

[David E. Eisenstat]

On Fri, 25 May 2007, Stephen Soltesz wrote:

> Hey, David,
>
> I have questions just for clarification.
>
> What distinguishes a slice that is called 'delegated' from a slice that 
> is called 'plc-instantiated'?

PLC and NodeManager behave differently depending on a slice's 
instantiation. If the instantiation is 'plc-instantiated', PLC will 
advertise the slice only to nodes to which it has been added. If it is 
delegated, it will tell all nodes about the slice. NodeManager will 
automatically instantiate all slices with instantiation 
'plc-instantiation' that PLC has told it about. It will instantiate slices 
with instantiation 'delegated' only when someone calls Create() for it.

The reason all nodes find out about a delegated slice is that the new 
NodeManager must have an indication from PLC that PLC knows about the 
slice before it will instantiate.

> You say that a ticket doesn't 'allow the bearer to do anything they 
> couldn't otherwise do.' I understand this as: in both cases there is 
> existing mechanism for instantiating the slice regardless of how the 
> slice info gets to NM.

Right, and the ticket grants no rights to control the mechanism, except 
possibly advancing when it acts by up to 15 minutes (or whatever the 
polling interval is).

> If there is more to delegation than this, I want to find out more. If 
> this is the essential distinction, then 'delegated' or 'PLC 
> instantiated' is just another slice attribute, right?  Is it treated 
> differently than this today?

Instantiation is actually part of the slice table proper, but yes, what 
I've said above is the extent of what this attribute controls. Delegation 
in PlanetLab also covers performing PLC/NodeManager API calls on someone 
else's behalf, which is not the subject of this thread.

> Does anyone with history have insight into whether anyone complained 
> about slices.xml (public slice info)?

Killing slices.xml was Mark Huang's idea as much as anyone else's, and I 
got the impression that his motivation was to have all access to PLC go 
through the API, rather than a particular security incident/concern.

In any case, Larry vetoed anonymous GetSliceTicket() calls, so this is 
perhaps a moot point.

-David