FORWARD FRAME CSTS
DISCUSSION
CCSDS SPRING 2017 MEETING
T. PHAM
OUTLINE
1. Progress on FF-CSTS Specification
• Work done up to now
• Work to follow
2. Discussion points
• Multiplexing
• Questions on FF-CSTS Strawman
• Questions on SFW
3. Development plan
4. Comments from draft of Section 2, if applicable
1. PROGRESS ON FF-CSTS SPECIFICATION
• Drafted Section 2 – Overview; Service Summary; Functional
Description; Service Management; Cross Support View;
Operational Scenario
• Leveraged on FF-CSTS Strawman, TD-CSTS and CSTS Guidelines, as well as EFCLTU Specification
• Created cross support view diagram
• Updated functional diagram with LDPC on TC path
CSTS
Guidelines
FF-CSTS
Strawman
writeup
Coverage
compliance
Format
& style
FF-CSTS
Specifications
Writeup
materials
Sampled
Forward
Service
Specifications
TD-CSTS
SFW
EF-CLTU
CROSS SUPPORT VIEW
• Add Cross Support View, per Guidelines
FUNCTIONAL DESCRIPTION DIAGRAM
• Add LDPC to “Forward CLTU
Generation FG”, given upcoming LDPC
BB
Forward CLTU Generation FG
Forward CLTU Generation FG
CLTU
CLTU
generation
BCH
encode
Random
Sequence
Generation
Synchronous Space Link Production (sync and channel coding)
block FEC
encoding none
convolutional
encoding
sync/async select
symbols
to RF
(physical
channel)
Forward
Frame
Service
Provision
instance
mux
SLPDUs
Forward
Frame
Service
Provision
instance
yes
no
CADU
sync
marker
attachment
convolutionallyencode
Random- yes
ization
no
R-S
encoding
idle SL-PDU
insertion
LDPC
encoding
randomize
block-encode
F-Frame production
sl-pdu-length
idle-sl-pdu
Random
Sequence
Generation
BCH
encode
Random
Sequence
Generation
CLTU
generation
Forward TC Space Link Processing FG
TC PLOP
LDPC
encode
sync/async
F-Frame provision
yes
no
PROGRESS ON FF-CSTS SPECIFICATIONS
• Make preparation for later sections on Service Composition & FF-CSTS
procedures
• Map sources of information and their transformation
• Among EF-CLTU, CSTS SFW and FF-CSTS
• Identify FF-CSTS specific procedures
• Understand why they are needed, relative to original SFW procedures
• Have few questions on FF-CSTS Strawman and CSTS SFW
INFORMATION SETS
EF-CLTU Operations
SFW Procedures
FF-CSTS Strawman
INFORMATION MAPPING
EF-CLTU Operations
3.3 CLTU-BIND
3.4 CLTU-UNBIND
3.5 CLTU-START
3.6 CLTU-STOP
3.7 CLTU-TRANSFER-DATA
3.8 CLTU-ASYNC-NOTIFY
3.9 CLTU-SCHEDULE-STATUSREPORT
3.10 CLTU-STATUS-REPORT
3.11 CLTU-GET-PARAMETERS
3.12 CLTU-THROW-EVENT
3.13 CLTU-PEER-ABORT
Addressed by FF-CSTS
Extended Procedures
-
Addressed by SFW Procedures
4.3 Association Control > BIND
4.3 Association Control > UNBIND
4.7 Buffered Data Processing > START
4.8 Sequence Controlled Data Processing > START TBD
4.7 Buffered Data Processing > STOP
4.8 Sequence Controlled Data Processing > STOP TBD
4.7 Buffered Data Processing > PROCESS-DATA
4.8 Sequence Controlled Data Processing >
PROCESS-DATA
TBD
4.7 Buffered Data Processing > NOTIFY
4.8 Sequence Controlled Data Processing > NOTIFY TBD
4.10 Cyclic Report > START/STOP/TRANSFER-DATA via Buffered/Sequence-Controlled Data Processing
> NOTIFY?
TBD
4.9 Information Query > GET
N/A
N/A
4.3 Association Control > PEER-ABORT
-
PROCEDURES DEFINED IN STRAWMAN
• TC Frame Processing sufficiently met by Sequence-Controlled Data Processing?
• Forward Synchronous Data Processing sufficiently met by Buffered Data
Processing?
2. DISCUSSION POINTS
•
•
•
•
Multiplexing
Clarifications on FF-CSTS Strawman
Clarifications on SFW
Document upkeep
MULTIPLEXING VC’S
• Multiplexing options similar to FSP specifications
•
•
•
FIFO
Absolute priority
Polling vector
CLARIFICATION ON FF-CSTS STRAWMAN
• Service provision – Possibility of each instance supports more than one VC?
(Strawman, p. 2-3)
• When configured to transfer TC or AOS transfer frames, each instance of the
F-Frame service is configured to support one or more virtual channels . The FFrame service provider inspects the frame header fields that identify the VC
and rejects frames that are not of the virtual channel(s) that are supported
by the F-Frame service instance
• Operational concept – unassigned VC (p. 2-5)
• It may be desirable to allow the F-Frame service to leave the VC assignment
unspecified, in which case the service instance would not inspect the frames and
enforce that they belong to the specified VC. This would allow the F-Frame service
to be used to transfer opaque blocks of octets for processing as though they were
transfer frames, even though they do not conform to CCSDS header specifications.
Such an “unspecified VC” option could only be used if the link protocol associated
with the opaque blocks is robust with respect to multiplexing blocks from multiple
sources, or if only one F-Frames service instance is assigned to the forward link (i.e.,
multiplexing is not used).
• Importance of supporting CADU?
• Requiring a separated refined Buffered Data Processing?
CLARIFICATION ON SFW
• Buffered Data Processing
• Impact to FF-CSTS per Note 3 (SFW, p.4-97) on all instances of Buffered
Data Processing procedures being blocked from one instance stops
reading the data from communications channel?
• Also, how to detect the affected instance to unlock this condition?
• This specification assumes that a service will only use a single instance of the
Buffered Data Processing procedure if that is operated in complete transfer mode.
If more than one instance is used then all instances of the Buffered Data
Processing procedure as well as any other procedures communicating via the
same connection may be blocked if one of the instances stops reading data from
the communications service.
OTHER CONSIDERATIONS
• Assignment of VC to each service instance
• How? Pre-assigned per users or dynamically assigned as FIFO?
• Buffered Data Processing
• Use cases of timely and complete transfer mode?
• Mixture allowed?
DOCUMENT DEVELOPMENT TIPS
• Cross references bookkeeping
• How best to handle this?
• Usage of Notes
• Guideline? (There are cases where Notes are used without main text)
• Development of ASN.1 structures
• How best to approach it?
3. DEVELOPMENT PLAN
• Pushing to have a complete draft of key sections by year end
• Annexes likely defined in next year
• Prototype planning
• Push for early prototype may overlap with the specifications development
• Past experience? Do-able?
4. FEEDBACK ON RECENT DRAFT?