[CESG] IOAG: Service Catalogue #1 / "packet / file / frame plumbing"
Gian.Paolo.Calzolari at esa.int
Gian.Paolo.Calzolari at esa.int
Tue Sep 27 16:53:52 UTC 2016
Peter,
a few replies below.
BTW, note that I missed a NOT and added a ? too much; i.e. I meant: I am
NOT sure I really understand what you mean for "packet / file / frame
plumbing".
Regards
Gippo
From: "Shames, Peter M (312B)" <peter.m.shames at jpl.nasa.gov>
To: "Gian.Paolo.Calzolari at esa.int" <Gian.Paolo.Calzolari at esa.int>
Cc: "CCSDS Engineering Steering Group - CESG
Exec(cesg at mailman.ccsds.org)" <cesg at mailman.ccsds.org>, "CESG"
<cesg-bounces at mailman.ccsds.org>, "Nestor.Peccia at esa.int"
<Nestor.Peccia at esa.int>
Date: 27/09/2016 18:15
Subject: Re: [CESG] IOAG: Service Catalogue #1 / "packet / file /
frame plumbing"
Hi Gippo,
Please go look at the SCCS-ADD (or ARD) which have carefully prepared (and
reviewed) diagrams that show just exactly what is involved in providing
the F-Frame service and an ABA forward file service built on top of it.
You are quite right that "Space/Encapsulation Packets, reliable/unreliable
transfer, COP usage" are functions that will need to be built to operate
the service and that it will be necessary to also define and build the
Service Management (SM) capabilities that will allow these functions to be
requested, managed, and configured by the service user. But that is not
all that will be required.
GPC: I never said this is the end of the story. My understand is that IOAG
gives requirements (sometimes with some warning) and CCSDS then does the
full work.
Alternativekly you could say
IOAG = what
CCSDS = how
The more significant "plumbing" that I was referencing includes: CFDP
protocol processing, SPP packet creating, frame creation (AOS or TC),
frame merging & multiplexing into separate VCs, and frame encoding. All
of those functions are defined in the ADD, some assigned to F-Frame (from
frame creation down), as a re-usable set of structures, and some to
specific services (such as CFDP and SPP). And all of those functions also
need SM capabilities defined. Furthermore, those functions, as defined in
the F-Frame service description, are re-usable and can support both ABA
and SSI protocol stacks and end-to-end services.
GPC: It seems we are basically matching about the idea of plumbing.
Indeed IOAG states that some plumbing (e.g. COP usage, reliable transfer)
can drive to complex systems.
With respcet to the "re-usable set of structures" I think you even go
beyond CCSDS unless you mean that part of that (future) standard can be
used for other standards. If you do not mean that and you intend reusable
software then you are into the implemenation domain (out of CCSDS in
principle)
To say that the "IOAG File services suppose a file is passed from A to B"
is to ignore all of the actual plumbing that is required to make this
happen. From a simplistic, "top level", view this may be acceptable, but
from a protocol view we really need to understand and define the whole set
of protocols in the stack(s) and the gyrations that they go through. We
cannot ignore the plumbing. So, in order to define a set of services that
maximize functionality for the users and minimize the effort on the part
of the ESLT (and the users) we took the approach defined in the SCCS-ADD.
You were one of the reviewers and approvers of that document, I assumed
you were familiar with it.
GPC: To say that the "IOAG File services suppose a file is passed from
A to B" is NOT to ignore all of the actual plumbing. It simply says that
the splitting of tasks is different and the related standards are
different. Again, CCSDS is the authority to determine the standardization
details.
I hope you recall that the origins of this F-Frame approach was in the
IOAG SISG, in a sub-committee that you, Wolfgang, and I participated in.
The focus there was on space internetworking, but the forward frame
service we cooked up was a general one and entirely suitable for the
"plumbing" of even these sorts of ABA services. And that is exactly what
is described in the SCCS-ADD.
GPC: I do recall but you forgot I was there working on many details of
F-Frame :o) . However, as mention, if Agency A wants to pass a file for
uplink to Agency B, the work snd the standards are different from those
implied when Agency A wants to pass frame for uplink to Agency B .
I think we should stick to the plan of developing the F-Frame first, and
building these other services on top of that framework instead of
developing another collection of "one-off" SLE-like services.
GPC: What has this to do with IOAG Catalogs. Catalog 1 and Catalog 2
define IOAG Services with some envisaged components (e.g. Space Link
Interface Standards & Ground Link Interface Standards & Service Management
Standards & Data Format Standards). Out of the catalogs, IOAG define
priorities and need dates to which CCSDS react accordingly of even in
disagreement.
Regards, Peter
From: Gian Paolo Calzolari <Gian.Paolo.Calzolari at esa.int>
Date: Tuesday, September 27, 2016 at 8:53 AM
To: Peter Shames <peter.m.shames at jpl.nasa.gov>
Cc: CCSDS Engineering Steering Group - CESG Exec <cesg at mailman.ccsds.org>,
CESG <cesg-bounces at mailman.ccsds.org>, Nestor Peccia
<Nestor.Peccia at esa.int>
Subject: Re: [CESG] IOAG: Service Catalogue #1 / "packet / file / frame
plumbing"
Peter,
I am sure I really understand what you mean for "packet / file /
frame plumbing"?
It looks to me that the description in Catalog 1 for the four files
services (two directions x two flavours) do underline that the service
provide will have to do quite some work (plumbing?) about
Space/Encapsulation Packets, reliable/unreliable transfer, COP usage,
You also say the CSTS F-Frame is supposed to provide most of this
plumbing but yor comment is ot about IOAG Catalog bu rather about the
service an agency should select.
In fact the IOAG File services suppose a file is passed from A to B, while
F-Frame supposes frames are passed fromA to B.
Regards
Gian Paolo
From: "Shames, Peter M (312B)" <peter.m.shames at jpl.nasa.gov>
To: "Nestor.Peccia at esa.int" <Nestor.Peccia at esa.int>, "CCSDS
Engineering Steering Group - CESG Exec(cesg at mailman.ccsds.org)"
<cesg at mailman.ccsds.org>
Date: 26/09/2016 21:33
Subject: Re: [CESG] IOAG: Service Catalogue #1
Sent by: "CESG" <cesg-bounces at mailman.ccsds.org>
Nestor,
I know that this is a late input, but after reading the IOAG Svc Cat #1 I
have a very real concern that I think needs to be surfaced. Four new
services have been introduced, the "Forward/Return CFDP-File Service Type"
and the "Forward/Return PACKETS-File Service Type". In reading through
the descriptions I find that they mention certain SM characteristics, but
fail to acknowledge the required presence of a whole lot of "packet / file
/ frame plumbing" that is missing in most of our current systems. Of
particular concern, from a standards and logistics point of view, is that
these new standards require a lot of the "plumbing" that CSTS F-Frame is
supposed to provide, but make no mention of that standard. In fact, the
precursor standards, "Forward Synchronous Encoded Frame Service Type" has
been dropped, and what is left is just some sort of weak "forward
reference" to a CSTS F-Frame service.
I think this is a huge mistake and that we should push back on it.
Here is the logic behind this:
1) FF-CSTS includes the key services and functions that are required
for anything like forward file, or forward packet, or forward DTN to work.
2) These functions include, quoting from the report "Users shall be
aware that IOAG Service Catalog 2 foresees a future CSTS Forward Frame
Service that is assumed will provide a forward service for [AOS] and
[TC-DLP] frames implementing multiplexing, frame fill and coding in the
provider and implementing the full stack down to the physical layer."
3) In order to implement a forward file or packet service all of
these functions, plus frame creation, must be present in the service
provider.
4) It makes little technical sense to create forward file and
forward packet services, as new separate services that embed all of these
function, instead of creating the FF-CSTS service and then building CFDP
and Packet service "plug-ins" on top of that which use this underlying
service.
In fact, this approach is exactly how the forward file service is now
described in the SCCS-ADD. I draw your attention to CCSDS 901.1-M-1, sec
5.2.2.2 and sec 6.2.2.2. In fact, fig 6-4 shows the relationships among
SM, CSTS F-Frame, the associated functions that are required, including
ranging, and also SLE R-AF, and fig 6-8 (ABA ESLT Forward-File Protocol
Building Blocks) shows how F-Frame and Fwd frame are designed to be
integrated. Any sort of forward packet service ought to just be a variant
of this.
My recommendation is that CCSDS push back on this IOAG Cat 1 request for
two new stand alone services and instead argue that CSTS F-Frame should be
done first, and these other new service built upon that base.
Regards, Peter
From: CESG <cesg-bounces at mailman.ccsds.org> on behalf of Nestor Peccia
<Nestor.Peccia at esa.int>
Date: Thursday, September 15, 2016 at 3:43 AM
To: CCSDS Engineering Steering Group - CESG Exec <cesg at mailman.ccsds.org>
Subject: [CESG] IOAG: Service Catalogue #1
REMINDER
Please let me have your comments (in particular from the CSS Area) by 22nd
Sept 2016 cob.
ciao
nestor
============================
Dear all,
Please find attached the Service Catalogue #1 that has been approved by
the IOAG.
You should be aware that the final approval regarding the editorial
updates from NASA is still pending. There is an on-going discussion
concerning service management ?function? vs. service management ?service?.
However, this version is good enough to be processed by the CESG.
[attachment "IOAG Service Catalog One.v2.0-Approved-20160823.pdf" deleted
by Nestor Peccia/esoc/ESA]
[attachment "IOAG Service Catalog One.v2.0-Approved-20160823withBars.pdf"
deleted by Nestor Peccia/esoc/ESA]
CESG will address this update during our next webex.
Main changes are :
1. forward / return CFDP file over terrestrial generic file
2. forward / return packet file service over terrestrial generic
file
3. Service Management functions
ciao
nestor
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