[Sls-slp] My comments on SDLS requirements on TM, TC, AOS / Presence of a parameter
Gian.Paolo.Calzolari at esa.int
Gian.Paolo.Calzolari at esa.int
Wed Jan 16 10:19:06 UTC 2013
thank you for your comments that will be discussed in the next
I would like just to report about the usage of the zero value to indicate
absence of a given parameter.
You suggest to delete the two managed "Presence of Space Data Link
Security Header" and "Presence of Space Data Link Security Trailer" as the
length parameter covers the presence/absence of the field.
We discussed extensively the matter and even acknowledging that a zero
value for the length can be used by an implementation to show absence, we
finally agreed not to use this option for the following reasons:
- As stated in the chapter introduction, the managed parameters are
defined in an abstract sense and are not intended to imply any particular
implementation of a management system. As a consequence presenting two
parameters instead of one is much more logical and explanatory to show
that the given parameter can be omitted. Of course this is not preventing
implementing the couple of parameters with a single "variable" in a real
- most of the times, using a zero value for the length imposes to describe
a non continuous range for the allowed values (e.g. 0 and 2 to 4 octets).
Conversely the use of two parameters really shows only the allowed values.
As well stating only "Integer" for allowed values would be incorrect.
If needed, we can add a note to state that implementers may combine the
two parameters in a single variable, but I do suggest keeping the two
parameters for clarity and readability.
"Kazz, Greg J (313B)" <greg.j.kazz at jpl.nasa.gov>
"Gian.Paolo.Calzolari at esa.int" <Gian.Paolo.Calzolari at esa.int>, "Marjorie
de Lande Long" <marjorie at delandelong.com>
"sls-slp at mailman.ccsds.org" <sls-slp at mailman.ccsds.org>, Moury Gilles
<Gilles.Moury at cnes.fr>
[Sls-slp] My comments on SDLS requirements on TM, TC, AOS
sls-slp-bounces at mailman.ccsds.org
G.P. and Marjorie,
Attached please find my green lines (Word editing feature) to the
documents you supplied us in Dec. 2012.
As you will see most of my edits are editorial in nature, except for the
issue regarding what should the link layer protocol do with the contents
of the frame when the SDLS authentication function returns a
authentication verification failure. In this case, I do not think there
should be an option as I stated in my notes, the link layer protocol
should not pass the data on to the user, but rather dispose of it and let
the user know that allow the user to know optionally that it was an error
detected by security fct. But we can discuss this further before and
during the Spring meeting.
[attachment "232x0b2pinkMAdeLLDec08+gpc+gjk.doc" deleted by Gian Paolo
[attachment "732x0p21MAdeLLDec08+gpc+gjk.doc" deleted by Gian Paolo
[attachment "132x0p11MAdeLLDec08+gpc.doc" deleted by Gian Paolo
Sls-slp mailing list
Sls-slp at mailman.ccsds.org
This message and any attachments are intended for the use of the addressee or addressees only. The unauthorised disclosure, use, dissemination or copying (either in whole or in part) of its content is not permitted. If you received this message in error, please notify the sender and delete it from your system. Emails can be altered and their integrity cannot be guaranteed by the sender.
Please consider the environment before printing this email.
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the SLS-SLP