Re: Satellites running IP

[Lloyd Wood <[e-mail]>]

On Fri, 14 Jun 2002, William Ivancic wrote:
> At 01:52 PM 6/14/02 +0100, Lloyd Wood wrote:
> >On Thu, 13 Jun 2002, David Carek wrote:
> >
> > > I'm looking for existing satellites that use IP or other Internet
> > > protocols on board or in their air to ground communications.  .....
> >
> > Really, isn't this what NASA et al. have been developing SCPS for?
>
> Does anyone know of someone "flying" an onboard SCPS stack?
>
> Does anyone know of any commercial applications that call the SCPS-TP
> options.  SCPS-FP is the only application one I know of.
>
> Does anyone know of a commercial vendor implementing a SCPS-NP router?  To
> take full advantage of some options in SCPS-TP, one needs as SCPS-NP router.
>
> We performed high-speed testing those SCPS options we could test and found
> no significant performance improvements.
> The report is being written, but not yet available.  The results were
> presented as the 2nd Space Internet Workshop in June and will be
> presented at SpaceOps 2002.
>
> http://roland.grc.nasa.gov/~ivancic/papers_presentations/papers.html
>
> Under PRESENTATIONS
>
> "SCPS-TP, TCP and Rate-Based Protocol Evaluation," (Includes multi-flow
> data) SpaceOps 2002 at Houston, TX, October 9-12, 2002 (Powerpoint) file
> size 951,808 bytes

the rest of the presentations are at
http://siw.gsfc.nasa.gov/agenda.html

(SIW1 has html conversions of all slides online; SIW2 is wholly
powerpoint.  Really, I'd like to see pdfs of the lot - all the
read-anywhere-platform-independent convenience of one, all the
download-a-single-file convenience of the other.)


> By the way, SCPS-TP advertises TCP's protocol number for reliable transport
> protocol selections.  It does this even if the pure rate-based transmission
> is used.  IMO, this is terrible as it  make QoS and queue management very
> difficult.

QoS and queue management shouldn't depend on what traffic is, but on
what traffic does imo - otherwise there's a semantic gap. When
rate-based, SCPS-TP is still sending TCP-style packets, so the
protocol identifier is valid.

L.

> I may be putting a rate-based protocol into a WRED
> queue.  Guess who loses.
>
> Will

<http://www.ee.surrey.ac.uk/Personal/L.Wood/><[e-mail]>