[Sis-csi] RE: networking details

[Ivancic, William D. (GRC-RCN0)]

If one is only using the data-link to get something from one physical
interface to another and one is not using the VC, why add that extra
management.

If one is extending the data-link and thus has to map a VC to IP and
back, this makes me nervous.  I don't like the security implications of
this.  I would rather do end-to-end security.

Will

******************************
William D. Ivancic
Phone 216-433-3494
Fax 216-433-8705
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http://roland.grc.nasa.gov/~ivancic 
 

> -----Original Message-----
> From: sis-csi-bounces at mailman.ccsds.org 
> [mailto:sis-csi-bounces at mailman.ccsds.org] On Behalf Of Keith Hogie
> Sent: Friday, February 09, 2007 2:20 PM
> Cc: CCSDS Cislunar Space Internetworking WG
> Subject: Re: [Sis-csi] RE: networking details
> 
> Adrian,
> 
>    A major concern is what you mentioned below about Virtual Channels.
> Those are a CCSDS data format that was developed 20 years ago 
> and was a fine solution for the time.  It sounds like you are 
> proposing that that VC data structure be maintained as the 
> underlying format for civil space programs for the next 20 
> years.  Does it make sense to plan on extending the life of a 
> 20 year old protocol format for 20 more years or is it time 
> for an upgrade or replacement of the VC format.
> 
>    During the last 20 years lots of protocols have come and 
> gone and been replaced by new ones that better suit users 
> current needs.  The commercial world primarily uses Frame 
> Relay and DVB over thousands of satellite links supporting 
> tens of thousands of users.  They have created a very large 
> commercial market of internationally interoperable products 
> with much better layering and function support than the basic 
> CCSDS VCDU.
> 
>    So it seems that a major question is whether the current 
> VC structure is the best structure to use for the future or 
> is it time to upgrade to more current solutions at that level?
> 
>    As far as future IP missions interoperating with future 
> missions that see no need for IP, that's fine but then they 
> don't have any plans to communicate with future IP missions 
> anyway.  Ground stations can still support both IP and non-IP 
> formats as many do already.
> The facilities, antennas, transmitters, and receivers still 
> need to do their jobs just the same.  The real question is 
> whether the bits coming off the space link go into a CCSDS 
> specific box that processes VCs or if the bits go into a 
> commercial router.  This is not a major change to the 
> infrastructure.  Yes, it is a change, but the communication 
> world has changed drastically over the last 20 years and we 
> need to decide if it is time for the civil space community to 
> catch up or if it wants to keep doing its own thing.
> 
> Keith
> 
> 
> Adrian J. Hooke wrote:
> > Maybe this is a good time to take stock of where we are. I 
> think that 
> > it is fair to say that there is broad international agreement that:
> > 
> > 1. We can see future requirements for the emergence of a more 
> > networked approach to space communications.
> > 2. Accordingly, we need to develop a migration strategy 
> that leads us 
> > towards more capable networking protocols.
> > 3. IP has a role in that migration strategy.
> > 
> > Beyond those elements of consensus, it's not clear that 
> there is much 
> > agreement on how or when to initiate change.
> > 
> > At 06:09 AM 2/8/2007, Keith Hogie wrote:
> >>   Moving to spacecraft using Internet protocols a change 
> to the whole 
> >> space communication concept.
> > 
> 
> snip
> 
> >> If we start launching some of our future systems with no 
> routed IP, 
> >> is there a clean path for them to "migrate" and be full 
> participants 
> >> in the future network.
> > 
> > Turn that around. If we start launching *some* of our 
> future systems 
> > exclusively with routed IP, is there a clean path for them 
> to be full 
> > participants in the future international community of missions that 
> > see no need for it?
> > 
> > Nobody's arguing that there won't be an increasing need for 
> portions 
> > of the international space mission support infrastructure to adopt 
> > more powerful routing technologies. When you need IP and IP 
> works, you 
> > should use IP. But does that mean that *everything* has to become 
> > IP-based, all at once? And yes, there's a migration path: 
> it's called 
> > international space standardization in general and in 
> particular it's 
> > called a Virtual Channel. It means that you can run part of your 
> > system using existing infrastructure, in parallel with part of your 
> > system using IP-based approaches. Change the mix of traffic 
> on the VCs 
> > and you can migrate with hardly any impact.
> > 
> 
> ----------------------------------------------------------------------
>    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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