<html><head><meta http-equiv="content-type" content="text/html; charset=utf-8"></head><body dir="auto">OK, David. <div>On the other hand it is not the task of SDLS to explain something defined in other standard. </div><div>Still a NOTE with a warning can help. </div><div><br></div><div>Regards</div><div><br></div><div>Gian Paolo<br><br><div dir="ltr" id="AppleMailSignature">Sent from my iPhone</div><div dir="ltr"><br>On 15. Jul 2019, at 15:26, David Koisser <<a href="mailto:David.Koisser@esa.int">David.Koisser@esa.int</a>> wrote:<br><br></div><blockquote type="cite"><div dir="ltr"><font size="2" face="sans-serif">Hi Gian Paolo,</font><br>
<br>
<font size="2" face="sans-serif">As you said, it needs to be implemented "with some caution". However, I think standards should either avoid pitfalls like this entirely (if possible) or hint at them *very* clearly. It should be crystal clear how to process frames. This is especially true for a security standard. </font><br>
<br>
<font size="2" face="sans-serif">I don't think the current version does enough to hint at the inherent ambiguity of the GVCID, which took me quite a while to actually notice.</font><br>
<br>
<font size="2" face="sans-serif">Cheers,</font><br>
<font size="2" face="sans-serif">David</font><br>
<div class="domino-section"><div class="domino-section-head"><span class="domino-section-title"><font size="2" color="#424282" face="sans-serif">Gian Paolo Calzolari---15/07/2019 11:04:56---David, I am mot sure I fully capture your issue/doubts.</font></span></div><div class="domino-section-body"><br>
<br>
<font size="1" color="#5F5F5F" face="sans-serif">From: </font><font size="1" face="sans-serif">Gian Paolo Calzolari/esoc/ESA</font><br>
<font size="1" color="#5F5F5F" face="sans-serif">To: </font><font size="1" face="sans-serif">"David Koisser (external)" <<a href="mailto:David.Koisser@esa.int">David.Koisser@esa.int</a>></font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Cc: </font><font size="1" face="sans-serif">"Lucas, John P.\(GSFC-5960\)" <<a href="mailto:john.p.lucas@nasa.gov">john.p.lucas@nasa.gov</a>>, "SLS-SEA-DLS" <<a href="mailto:sls-sea-dls-bounces@mailman.ccsds.org">sls-sea-dls-bounces@mailman.ccsds.org</a>>, "<a href="mailto:sls-sea-dls@mailman.ccsds.org">sls-sea-dls@mailman.ccsds.org</a>", "Kazz, Greg J (313B)" <<a href="mailto:greg.j.kazz@jpl.nasa.gov">greg.j.kazz@jpl.nasa.gov</a>>, "Matt Cosby" <<a href="mailto:matt.cosby@goonhilly.org">matt.cosby@goonhilly.org</a>></font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Date: </font><font size="1" face="sans-serif">15/07/2019 11:04</font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Subject: </font><font size="1" face="sans-serif">Re: [Sls-sea-dls] SDLS EP GVCID Issues</font><br>
<hr width="100%" size="2" align="left" noshade="" style="color:#8091A5; "><br>
<br>
<font size="2" face="sans-serif">David,</font><br>
<font size="2" face="sans-serif"> I am mot sure I fully capture your issue/doubts.</font><br>
<font size="2" face="sans-serif">There are indeed different definitions sometimes coming ether from real difference (TM and AOS do not have MAPs) or from some different terminology for historical reasons.</font><br>
<br>
<font size="2" face="sans-serif">The general definition is indeed GVCID = TFVN + SCID + VCID & GMAPID = TFVN + SCID + VCID + MAPID with the caveat that the MAP Identifies may not exist and that the total length depends on the applied standard.</font><br>
<font size="2" face="sans-serif">Implementers need to implement it with some caution.</font><br>
<br>
<font size="2" face="sans-serif">The mapping between USLP and Proximity is due - as far as I remember - that Proximity-1 never really defined a GVCID.</font><br>
<br>
<font size="2" face="sans-serif">Greg & Matt, copied here, may add more comments.</font><br>
<br>
<font size="2" face="sans-serif">Note also tat there a pending corrigendum (not yet on web but approved) for CCSDS 320.0-M-7 CCSDS Spacecraft Identification Field Code Assignment Control Procedures. Magenta Book. Issue 7. November 2017.</font><br>
<br>
<font size="2" face="sans-serif">Regards</font><br>
<br>
<font size="2" face="sans-serif">Gian Paolo</font><br>
</div></div><br>
<div class="domino-section"><div class="domino-section-head"><span class="domino-section-title"><font size="2" color="#424282" face="sans-serif">"David Koisser (external)" ---15-07-2019 10:21:41---Hello everyone, We noticed some more issues regarding the GVCID / MAPID. After checking,</font></span></div><div class="domino-section-body"><br>
<br>
<font size="1" color="#5F5F5F" face="sans-serif">From: </font><font size="1" face="sans-serif">"David Koisser (external)" <<a href="mailto:David.Koisser@esa.int">David.Koisser@esa.int</a>></font><br>
<font size="1" color="#5F5F5F" face="sans-serif">To: </font><font size="1" face="sans-serif">"<a href="mailto:sls-sea-dls@mailman.ccsds.org">sls-sea-dls@mailman.ccsds.org</a>"@esa.int</font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Cc: </font><font size="1" face="sans-serif">"Lucas, John P.\(GSFC-5960\)" <<a href="mailto:john.p.lucas@nasa.gov">john.p.lucas@nasa.gov</a>></font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Date: </font><font size="1" face="sans-serif">15-07-19 10:21</font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Subject: </font><font size="1" face="sans-serif">[Sls-sea-dls] SDLS EP GVCID Issues</font><br>
<font size="1" color="#5F5F5F" face="sans-serif">Sent by: </font><font size="1" face="sans-serif">"SLS-SEA-DLS" <<a href="mailto:sls-sea-dls-bounces@mailman.ccsds.org">sls-sea-dls-bounces@mailman.ccsds.org</a>></font><br>
<hr width="100%" size="2" align="left" noshade="" style="color:#8091A5; "><br>
<br>
<br>
<font size="2" face="sans-serif">Hello everyone,</font><font size="3" face="serif"> <br>
</font><font size="2" face="sans-serif"><br>
We noticed some more issues regarding the GVCID / MAPID. After checking, it turns out different standards have very different interpretations. I attached screenshots of the regarding sections of the blue books for your convenience.</font><font size="3" face="serif"> <br>
</font><font size="2" face="sans-serif"><br>
The SDLS EP GVCID seems to be an aggregate of the longest defined versions of the respective fields. To my knowledge SDLS EP seems to be the only and first document, which specifically defines a (merged) GVCID. All other standards only define them as GVCID = TFVN + SCID + VCID & GMAPID = TFVN + SCID + VCID + MAPID (without sizes). In USLP the relation between old and new frames is defined, but only for Proximity-1 (see C1.1). I am not sure if this is more clearly explained somewhere else.</font><font size="3" face="serif"> <br>
</font><font size="2" face="sans-serif"><br>
In SDLS EP I see two problems. First, there is no explanation or justification for the lengths. Second, this may possibly lead to severe bugs, e.g. overflowing a TM VCID bigger than what fits in the defined 3 bits, like 16 bits in USLP or worse, 6 bits in TC (with identical TFVN as TM). Improper sanity checks here may even lead to security critical bugs.</font><font size="3" face="serif"> <br>
</font><font size="2" face="sans-serif"><br>
Cheers,</font><font size="3" face="serif"> </font><font size="2" face="sans-serif"><br>
David</font><font size="3" face="serif"> <br>
</font><br>
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