[Sls-slp] AOS 5-year review: typo and VCF Service issues

Tue Oct 27 22:31:23 UTC 2020

Dear All,
        the typo remark as presented in John's e-mail looks correct (but I 
did not check the documents).

For the other remark I am getting more doubts.
The current sentence is not looking correct to me, but I am not sure the 
proposed correction is the best one.

As specified in 2.2.4 RESTRICTIONS ON SERVICES bullet c: If the Virtual 
Channel Frame Service exists on a Virtual Channel, other services shall 
not exist simultaneously on that Virtual Channel. 
Let's consider the original sentence:  “The Virtual Channel Frame Service 
transfers the independently created AOS Transfer Frames through a space 
link, possibly together with AOS Transfer Frames identified by other GVCID 
values created by the service provider itself.” 
If we split it, I read something like this
 “The Virtual Channel Frame Service transfers the independently created 
AOS Transfer Frames through a space link.
 The Virtual Channel Frame Service transfers possibly also AOS Transfer 
Frames identified by other GVCID values created by the service provider 
itself.” 
In other words it looks as the other frames are also transferred by the 
VCF Service while they are transferred by other services (or service 
instances) on other VCs/MCs.
The same issue rises also with the rewording proposed by John.

A possible improvement could then be something like this:
“Each Virtual Channel Frame Service instance transfers the independently 
created AOS Transfer Frames through a space link.
Those AOS Transfer Frames are possibly multiplexed on the space link 
together with other AOS Transfer Frames identified by different GVCID/MCID 
values. 
These other AOS Transfer Frames can have been created by other VCF/MCF 
Service instances and/or by the service provider itself.”

I understand this is likely not to be the best formulation, but may be a 
good starting point for a less ambiguous formulation.

I also guess that a similar improvement should apply to 2.2.3.7 for the 
sentence "The Master Channel Frame Service transfers the independently 
created AOS Transfer Frames through the space link, together with AOS 
Transfer Frames created by the service provider itself." noting that <If 
the Master Channel Frame Service exists on a Master Channel, other 
services shall not exist simultaneously on that Master Channel.>.

Best regards

Gian Paolo

From:   "Kazz, Greg J\(US 312B\) via SLS-SLP" <sls-slp at mailman.ccsds.org>
To:     "Kazz, Greg J (US 312B) via SLS-SLP" <sls-slp at mailman.ccsds.org>
Date:   27-10-20 22:53
Subject:        [Sls-slp] FW: [EXTERNAL] RE: Updated TM & AOS 5-year 
review files from SLP WG meeting Oct 27
Sent by:        "SLS-SLP" <sls-slp-bounces at mailman.ccsds.org>

Dear SLP WG members,

John Pietras has what I believe are some good points below.
Please let me know your opinion of his proposed changes below

Thanks!
Greg
Chair SLP WG

From: John Pietras <john.pietras at gst.com>
Date: Tuesday, October 27, 2020 at 2:23 PM
To: "Kazz, Greg J (US 312B)" <greg.j.kazz at jpl.nasa.gov>
Subject: [EXTERNAL] RE: Updated TM & AOS 5-year review files from SLP WG 
meeting Oct 27

Dear Greg and all,
I’ve taken a quick look at the updates TM and AOS books and I found a typo 
and a statement that I think is misleading.

First the typo – As modified, the first sentence of the second paragraph 
under 2.2.3.6 of the AOS book now reads “For a given service instance, 
only one user, identified with the GVCID of the Virtual Channel, and each 
VCF Service instance on a physical channel must utilize a unique GVCID 
value.” The phrase “can use this service on a Virtual Channel” has been 
erroneously deleted. 
The sentence should read “For a given service instance, only one user, 
identified with the GVCID of the Virtual Channel, can use this service on 
a Virtual Channel, and each VCF Service instance on a physical channel 
must utilize a unique GVCID value.”

What I believe to be a misleading statement appears in two forms in both 
the AOS and TM books. The first sentence of the third paragraph under 
2.2.3.6 of the AOS book now reads “The Virtual Channel Frame Service 
transfers the independently created AOS Transfer Frames through a space 
link, possibly together with AOS Transfer Frames identified by other GVCID 
values created by the service provider itself.” 
My interpretation of this sentence is that there can be only one instance 
of the VCF Service per space link, with the implication that all other VCs 
on the space link are generated “by the service provider itself”. 
I believe that a more accurate, less ambiguous statement is 
“Each Virtual Channel Frame Service instance transfers the independently 
created AOS Transfer Frames through a space link, possibly together with 
AOS Transfer Frames identified by other GVCID values created by users of 
other VCF Service instances, users of Master Channel Frame service 
instances (see 2.2.3.7), and/or by the service provider itself.”

If my suggestion is accepted, the same change should be applied to 2.2.3.6 
of the TM book. 

The analogous situation applies to the MCF Service. The equivalent 
modification would be to change first sentence of the third paragraph 
under 2.2.3.7 of the AOS book (and 2.2.9 of the TM book) to read “Each 
Master Channel Frame Service instance transfers the independently created 
AOS Transfer Frames through the space link, possibly together with AOS 
Transfer Frames identified by other MCID values created by users of other 
MCF Service instances or by the service provider itself.“

Best regards,
John 

From: SLS-SLP [mailto:sls-slp-bounces at mailman.ccsds.org] On Behalf Of 
Kazz, Greg J (US 312B) via SLS-SLP
Sent: Tuesday, October 27, 2020 12:43 PM
To: Kazz, Greg J (US 312B) via SLS-SLP <sls-slp at mailman.ccsds.org>
Subject: [Sls-slp] Updated TM & AOS 5-year review files from SLP WG 
meeting Oct 27

Dear SLP WG,

Attached please find two files as a result of the 5-year review:

1.      Updated 132.0-B TM SDLP book modified during our SLP WG meeting 
today on Oct 27.
2.      Updated 732.0-B AOS SDLP book modified during our SLP WG meeting 
today on Oct 27.

When I have a chance, I will load both of them to the SLP WG CWE directory 
under the Fall 2020 meeting.

Best regards,

Greg Kazz
Principal Engineer
Technical Group Supervisor,
PSSE/EEISE/PPSE (312B)
Jet Propulsion Laboratory
4800 Oak Grove Dr., M/S 301-490
Pasadena, CA 91109
1+(818)393 6529(voice)
1+(818)393 6871(fax)
email: greg.j.kazz at jpl.nasa.gov 
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