[Css-csts] FW: Ambiguous specification of CLTU transfer buffer behavior

[John Pietras]

Members of the CSTSWG: 

 

The following email exchange describes an ambiguity encountered in the
defined behavior of the CLTU buffer in the FCLTU specification. If you
have an interest in this issue, please comment on whether the behavior
of the CLTU buffer should be more tightly defined in the FCLTU
specification.

 

Best regards,

John

________________________________

From: John Pietras 
Sent: Friday, May 30, 2008 12:33 PM
To: 'Boxell, Jeff'; css-csts at mailman.ccsds.org
Cc: Michael Stoloff; Kazz, Greg J (X-JPL); Peter Shames; Erik Barkley;
Fred Brosi; Petkevich, Michael; Kluksdahl, Norman C. (JSC-DD22); Hill,
Frank9
Subject: Ambiguous specification of CLTU transfer buffer behavior

 

Jeff,

It's possible that the ambiguity that you have encountered was
intentionally left "loose" to accommodate some flexibility in vendor
implementations and user requirements, but I am not certain of that.
I'll forward the pertinent part of your note to the membership of the
Cross Support Transfer Service Working Group, which is responsible for
maintaining the SLE specifications. 

 

Best regards,

John

 

________________________________

From: Boxell, Jeff [mailto:jeff.boxell at lmco.com] 
Sent: Friday, May 23, 2008 11:55 AM
..

Subject: RE: SLE provider

 

... I would like to get your thoughts on a possible upgrade to the SLE
Spec based the difficulties we experienced having 1 SLE User
implementation talk to two different vendor SLE provider implementations
(one vendor user for real-time operations, another used strictly for
simulations).  Each vendor managed the reporting of the CLTU buffer
level differently.  One vendor extracted a CLTU to be radiated and
immediately started radiating the CLTU; the other vendor extracted a
CLTU and staged it for radiation so that 2 CLTUs were typically outside
the CLTU buffer (one being radiated, the other waiting to be radiated).
To keep our buffer level management and reporting in sync, we asked the
SIM vendor to tailor their implementation to meet the other's
implementation and they willingly did this.  Together we looked at the
Specs and saw that this level of detail was not explicitly specified.
Can you give me some feedback on what might be done to prevent others
from encountering this problem (e.g. should I submit an update to the
Spec)?  

...

 

Jeff Boxell

Lockheed Martin Mission Services

Houston, Tx

281-853-2240

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