[Sis-csi] Finishing off the architecture book

[James Rash]

Keith,

Attached is a version with my suggestions in revisions mode.

Cheers...
Jim

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On Aug 3, 2006, at 9:32 AM, Scott, Keith L. wrote:

> All,
>
> I'd like to skip the telecon today, but we need to get the  
> architecture
> book finished off.  I think the last thing we need is to introduce the
> 'phasing' notion as we discussed in Rome, and I had the action to  
> write
> some text to that effect.  Let's discuss over email.  I will also be
> out next week, but back the week after.
>
>
> How about the following as a short section on phasing in capability:
>
> 6	PHASED INTRODUCTION OF CAPABILITIES
>
> Moving from traditional operations to a completely IP-based system in
> one step would be jarring at best.  While the concepts of automated
> data forwarding, routing, and network quality of service are mature  
> and
> have operational experience terrestrially, their applicability to a
> 'MANET of networks' composed of orbiting satellites, orbiting relays,
> lunar outposts, and lunar transit vehicles leaves several questions.
> One of the largest open questions is how to structure a dynamic  
> routing
> protocol to handle the changing connectivity among various spacecraft.
> We thus propose developing the protocols to populate the architecture
> presented here in three phases:
>
> 1.	Simple spacecraft without in-space routing
> 2.	Simplified in-space routing among cooperating spacecraft
> 3.	Advanced in-space routing among multiple spacecraft
>
> In the first phase, spacecraft will not be required to use other
> spacecraft as IP routers in order to reach the ground.  This admits  
> the
> use of layer-2 relays such as TDRSS, but greatly simplifies
> network-layer routing.  Because the spacecraft may use different  
> ground
> stations and hence change their points of attachment to the Internet,
> routing from ground-based systems to space-based systems is an issue
> (routing toward the ground-based systems, which do not move within the
> Internet topology, is trivial).  Techniques such as MobileIP would  
> work
> here, as would a more managed approach where GRE tunnels from the
> spacecraft's 'home' location to the correct ground station are
> configured and maintained from a mission operations center.
>
> In the second phase, we will consider simple routing among spacecraft
> that are designed to know of each other's existence and where the
> in-space routing does not require a full dynamic routing protocol to
> manage connectivity.  An example of such a situation would be an
> orbiter-lander mission, where the lander could route data via the
> orbiter to reach Earth.  This situation is not much more complex than
> the first phase, since the only thing changing from the point of view
> of the terrestrial routing is the orbiter's point of attachment to the
> ground.
>
> In the third phase we will consider the general case of
> spacecraft-to-spacecraft routing where two spacecraft, A and B, can  
> use
> each other as relays to communicate with the ground, or may  
> communicate
> with the ground directly.  This is more complicated because spacecraft
> A's could be directly attached to the ground (via a DTE/DFE link), in
> which case packets from other locations on the ground to spacecraft A
> should be routed to spacecraft A's home (assuming some form of
> tunneling is used).  Spacecraft A's point of attachment could also be
> via spacecraft B, in which case packets to spacecraft A would need to
> be routed toward spacecraft B's home (again, assuming some form of
> tunneling from spacecraft B's home location to the current ground
> station serving spacecraft B).
>
> ========
>
> 		--keith
>
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