[Sis-csi] RE: networking details

[Adrian J. Hooke]

At 01:37 PM 2/9/2007, Dave Israel wrote:
>I think the question is still "Why are we debating the link layer again 
>when people are still not convinced that there is value in basic 
>networking in the first place?"

Dave: we are discussing the Link layer precisely because of that very 
point. Namely, a very large number of people across the international 
community simply aren't buying into the basic need for networking in space.

The whole reason for raising this issue again was to point out that the 
real world is rarely black and white. Individuals who bloviate about the 
immaculate properties of black or the divine nature of white are unhelpful. 
They polarize opinion and they turn off the vast majority of people who see 
the shades of gray. The real world of space missions is populated mainly by 
pragmatic and conservative engineers who will accept change when they are 
convinced of the need for change, not because some self-appointed guru 
lectures them that it will be good for their souls.

One way that you convince people to migrate from black to white is to offer 
hybrid solutions that allow them to transition through gray in an 
evolutionary manner. The Link layer is important because it needs to 
facilitate such evolution. We have existing CCSDS Link layers that can 
equally well support black, white or gray traffic. They are layered, they 
are robust, they were specifically designed for space mission use, they are 
well understood, they are extensively used, they are well supported by 
industry and they are agnostic to the technologies above them. They can 
handle bitstreams or octet streams or TDM or Ethernet frames or Space 
Packets or IPv4 or IPv6 or ISO-8473 or LTP/DTN or whatever - all mixed 
together on a single Physical channel if desired - and they simply don't care.

The case for basic networking is almost certainly going to be made in the 
international community by offering people an evolutionary path. The 
existing CCSDS Link layers are the platforms on which the CCSDS Cislunar 
working group in the CCSDS Space Internetworking Services Area is going to 
build its case. End of subject. If people want to propose new Link layers, 
they can make their separate cases to the CCSDS Space Link Services Area 
Director.

Best regards
Adrian

Adrian J. Hooke
Chairman, CCSDS Engineering Steering Group (CESG) 
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