<span style=" font-size:10pt;font-family:sans-serif">David,</span>
<br><span style=" font-size:10pt;font-family:sans-serif">
I am mot sure I fully capture your issue/doubts.</span>
<br><span style=" font-size:10pt;font-family: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.</span>
<br>
<br><span style=" font-size:10pt;font-family: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.</span>
<br><span style=" font-size:10pt;font-family:sans-serif">Implementers need
to implement it with some caution.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">The mapping between
USLP and Proximity is due - as far as I remember - that Proximity-1 never
really defined a GVCID.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Greg & Matt,
copied here, may add more comments.</span>
<br>
<br><span style=" font-size:10pt;font-family: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.</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Regards</span>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Gian Paolo</span>
<br>
<br>
<br>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">From:
</span><span style=" font-size:9pt;font-family:sans-serif">"David
Koisser (external)" <David.Koisser@esa.int></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">To:
</span><span style=" font-size:9pt;font-family:sans-serif">"sls-sea-dls@mailman.ccsds.org"@esa.int</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Cc:
</span><span style=" font-size:9pt;font-family:sans-serif">"Lucas,
John P.\(GSFC-5960\)" <john.p.lucas@nasa.gov></span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Date:
</span><span style=" font-size:9pt;font-family:sans-serif">15-07-19
10:21</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Subject:
</span><span style=" font-size:9pt;font-family:sans-serif">[Sls-sea-dls]
SDLS EP GVCID Issues</span>
<br><span style=" font-size:9pt;color:#5f5f5f;font-family:sans-serif">Sent
by: </span><span style=" font-size:9pt;font-family:sans-serif">"SLS-SEA-DLS"
<sls-sea-dls-bounces@mailman.ccsds.org></span>
<br>
<hr noshade>
<br>
<br>
<br><span style=" font-size:10pt;font-family:sans-serif">Hello everyone,</span><span style=" font-size:12pt">
<br>
</span><span style=" font-size:10pt;font-family: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.</span><span style=" font-size:12pt"> <br>
</span><span style=" font-size:10pt;font-family: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.</span><span style=" font-size:12pt">
<br>
</span><span style=" font-size:10pt;font-family: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.</span><span style=" font-size:12pt">
<br>
</span><span style=" font-size:10pt;font-family:sans-serif"><br>
Cheers,</span><span style=" font-size:12pt"> </span><span style=" font-size:10pt;font-family:sans-serif"><br>
David</span><span style=" font-size:12pt"> <br>
</span>
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[attachment "USLP.PNG" deleted by Gian Paolo Calzolari/esoc/ESA]
[attachment "TM.PNG" deleted by Gian Paolo Calzolari/esoc/ESA]
[attachment "TC.PNG" deleted by Gian Paolo Calzolari/esoc/ESA]
[attachment "Segment.PNG" deleted by Gian Paolo Calzolari/esoc/ESA]
[attachment "SDLS EP.PNG" deleted by Gian Paolo Calzolari/esoc/ESA]
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