[Sis-csi] IPv6?

[Chris.Taylor at esa.int]

I am well aware of the emerging initiatives in DTN and the fact that by
introducing another layer of bundling we could resolve some of the issues
with IP. I'm also well aware that we can fly a commercial router just for the
benefit of sending point to point traffic from a payload to ground. Something
we can do anytime with existing software and at zero cost. But this is not my
point. I'm asking what we really need in the next 15 year or so period, a
period in which the commercial terrestrial standards will evolve out of all
recognition and many (most) of the standards used today will have long gone,
as will the commercial support and components needed for long duration
missions.  Just how many IP addresses are we going to need for the flight
infrastructure in place at the time - 4, 5? Wow. Do we really need a fully IP
routed flight architecture to support a few IP cognizant nodes.

I would contend that the recent pushing of IP in the context of exploration
is essentially hype. Dangerous hype at that, as it obscures the real issues
that need to be tackled to resolve existing problems and agree an
evolutionary path forwards. Until I see a realistic configuration (not the
futuristic, commercially driven nonsense) of what we can expect in 15-20
years, and set of accompanying comms requirements that justify the need for
IP, I will continue to doubt the goals, objectives and understanding of the
IP exponents.

//ct.


                                                                             
             Lloyd Wood                                                      
             <L.Wood at surrey.ac.                                              
             uk>                                                          To 
             Sent by:                   Chris.Taylor at esa.int                 
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             ilman.ccsds.org            CCSDS Cislunar Space Internetworking 
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                                                                     Subject 
             08/06/2007 19:56           RE: [Sis-csi] IPv6?                  
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             
                                                                             




At Friday 08/06/2007 17:45 +0200, Chris.Taylor at esa.int wrote:
>Just to stir things up a bit, has it really been decided that we will use IP
>on our future links. From the discussion it seems like a done deal but our
>ESA studies and opinion is that IP doesn't bring us much other than a bit
>more address space that we probably don't need anyway. Rather than  discuss
>the merits of IPv4 and 6 it may be more productive to critically examine the
>application of IP to see how it may be employed or not. I should say that I
>have no particular issue with the use of IP its just that I think the
problem
>is much wider and by concentrating on v4/v6 there is a danger of missing the
>real problems - IP doesn't work on links that have disjoint connectivity

Actually, IP works just fine on links with disjoint connectivity, as large
amounts of delay/disruption tolerant networking work and mobile ad-hoc work
by many people have shown. For example, we've developed our own IP/UDP-based
transport protocol for moving files over disjoint links, and there are other
protocols that work over IP in these environments. TCP won't work well, but
then TCP's operational range is surprisingly limited. TCP is not IP.

See:
http://www.ee.surrey.ac.uk/Personal/L.Wood/dtn/
ftp://ftp-eng.cisco.com/lwood/dtn/README.html (IE users: passive ftp must be
ON in Tools/Options... Advanced tab)
- Saratoga: a Delay-Tolerant Networking convergence layer with efficient link
utilization, Lloyd Wood, Wesley M. Eddy, Will Ivancic, Jim McKim and Chris
Jackson, submitted to the Third International Workshop on Satellite and Space
Communications (IWSSC '07), September 2007.
- Saratoga: A Convergence Layer for Delay Tolerant Networking, Lloyd Wood,
Wesley M. Eddy, Will Ivancic, Jim McKim and Chris Jackson, work in progress
as an internet draft, version -00 submitted to the IETF, May 2007.

For a detailed discussion of how IP can be used in the disjoint environment
of intermittent space links, see:
http://www.ee.surrey.ac.uk/Personal/L.Wood/cleo/
ftp://ftp-eng.cisco.com/lwood/cleo/README.html (IE users: passive ftp must be
ON in Tools/Options... Advanced tab)
- Using Internet nodes and routers onboard satellites, Lloyd Wood, Will
Ivancic, Dave Hodgson, Eric Miller, Brett Conner, Scott Lynch, Chris Jackson,
Alex da Silva Curiel, Dave Cooke, Dan Shell, Jon Walke and Dave Stewart,
special issue on Space Networks, International Journal of Satellite
Communications and Networking, vol. 25 issue 2, pp. 195-216, March/April 2007
- particularly section 14.

The primary argument for using IP imo is that you can just reuse
well-developed commercial technologies without reinventing the wheel,
minimising your overall software development and testing costs.

(How much is esa spending on developing Spacewire? IP already runs well over
LVDS HDLC serial links, and is used on them in space.)

regards,

L.


<http://www.ee.surrey.ac.uk/Personal/L.Wood/><L.Wood at surrey.ac.uk>

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