[Sis-csi] IPv4 and IPv6

[Keith Hogie]

Keith,

   This is a nice list of issues but in the end I think your last
sentence below is probably the real issue.  Since it takes many
years (5-10 or more) for new NASA missions to actually get into
operation going straight to IPv6 makes lots of sense.

   We can have lots of technical discussions on the trades you
mentioned but in the end IPv6 has some nicer functionality
and makes lots of sense for systems 10 years from now.  If we
start designing and deploying IPv4 for space, lots of things
will get cast in concrete and making changes in 10 years will
be very difficult.  Then 20 years from now NASA will still be
running IPv4 and Nascom 4800 bit blocks:).

   I realize that most of us don't see much IPv6 deployment now
but at an IPv6 presentation a few weeks ago I heard
the following:

  1 - The US owns 70% of all IPv4 address space, doesn't leave
much for the rest of the world.

  2 - Organizations like Apple, and MIT each have more IPv4
address space than all of China

  3 - Hundreds of millions of mobile devices will be needing
IP addresses in the future and they will end up with IPv6

   Since IPv6 is coming and NASA doesn't currently have any
installed IPv4 space architecture, it seems to make sense
to just start out with IPv6.  Otherwise just when we
finally get IPv4 in place it will be time to replace it.

   The only real argument against it is a few more bytes
of overhead.  But then those bytes also provide functionality
and there are compression options that can greatly
reduce the overhead.  Plus we can all make Howie happy
if we go with IPv6 since security options are required
as part of IPv6.  This adds bytes but adds functionality too.
Also, when we had 1 Kbps links, overhead was critical but
as we move to 100 Mbps links overhead issues are not
as critical since users won't be fully utilizing the link
anyway.

Keith Hogie



Scott, Keith L. wrote:

> Now that we're coming to the end (again) of justifying an end-to-end, 
> routed, automated, networked architecture, one of the big questions 
> looming on our horizon will be the choice of network layer.  Taking just 
> the low-RTT, connected, low-error rate connected (terrestrial-like) 
> environments, the Internet Protocol seems like it would certainly 
> deserve consideration.  The choice of IP version 4, IP version 6, or 
> dual-stack implementations is sure to come up.  What's below is my first 
> cut at trying to figure out what a trade between v4 and v6 would look like.
> 
> I'm perfectly willing to be argued off of any position here (except 
> possibly my opionions regarding DoD and OMB mandates :)  I'm hoping this 
> can be a starting point for a discussion and possibly fodder for a later 
> trade study.  What's NOT here is an evaluation of complexity/cost of 
> starting with IPv4 on space links and then deciding that we really *do* 
> have to go with IPv6.
> 

-- 
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   Keith Hogie                   e-mail: Keith.Hogie at gsfc.nasa.gov
   Computer Sciences Corp.       office: 301-794-2999  fax: 301-794-9480
   7700 Hubble Dr.
   Lanham-Seabrook, MD 20706  USA        301-286-3203 @ NASA/Goddard
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