[Sls-slp] Material to discuss during 3rd USLP Telecon

Kazz, Greg J (312B) greg.j.kazz at jpl.nasa.gov
Fri Feb 12 19:47:50 UTC 2016

Dear SLP WG,

I will soon create a doodle poll for the 3rd USLP White Book telecon.
The focus will be on Section 2 of the post telecon 2 white book as well as a trial balloon pitch for an additional type of Insert Zone service, called On-demand insert.

You can find the latest version of the USLP white book post telecon 2 on the CWE under:


It contains the date feb 9 and post telecon 2 in the word file name.

Topic 1 (Section 2 review) is spearheaded by Gian Paolo whose comments you will find in the CWE under:


At least two key questions need to be discussed by SLP WG concerning the review of Section 2. They are:

1) Shall USLP retain the TC Coding capability that a protocol data unit transferred can contain several frames?
The fact that TC coding allows it does not exclude a possible limitation on the USLP side (e.g. SLE FSP explicitly forbids the option of including several TC frames in a CLTU).
We shall remember that several frames in a CLTU does decrease performance.
2) Shall any reference to Proximity-1 coding be removed from the USLP Blue Book as long as there is no agreed adaptation for that blue book?
Note: NASA has submitted an agenda item to the C&S WG chairman to describe changes to the CCSDS 211.2-B-2 (Prox-1 C&S Blue Book) including CWE project details  to allow USLP transfer frames over the Proximity link.

Topic 2 (On-demand Insert Service) is spearheaded by Ed Greenberg. The post telecon 2 white book contains trial sections describing and standardizing the two types of Insert Service. The concept is below:

The concept of the two types of Insert Service follows:
USLP provides two complementary types of Insert Service: a) Isochronous and b) On-demand. Only one Insert Service type is allowed on a Physical Channel at any given time.
The Isochronous Insert Service provides transfer of private, fixed-length, octet-aligned service data units across a space link in a mode which efficiently utilizes the space link transmission resources at relatively low data rates.  The service is unidirectional, periodic, and sequence-preserving.  The service does not guarantee completeness, but may signal gaps in the sequence of service data units delivered to a receiving user.
For a given service instance, only one user, identified with the Physical Channel Name of the Physical Channel, can use this service on a Physical Channel. Service data units from different users are not multiplexed together within one Physical Channel. The presence of the Insert Zone is signaled by Managed Parameters.
The On-demand Insert Service provides the optional transfer of private, variable length, octet-aligned service data units across a space link in an episodic manner. The service is unidirectional, asynchronous, and non-sequence preserving. The Insert Zone length may vary between 1 and 255 octets and is specified in the first octet of the Insert Zone. The presence of the on-demand Insert Zone is signaled by the On-demand IZ flag in the TF header.
Multiple users may use this on-demand Insert Service on a Master Channel, identified with the VCID of the frame which contains the On-demand IZ flag set to ‘1’.

Best regards,
Chairman SLS-SLP WG

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