SIS-DTN
Download
1 / 10

SIS-DTN LTP Protocol Specification - PowerPoint PPT Presentation


  • 225 Views
  • Uploaded on

SIS-DTN LTP Protocol Specification. Agenda. Goals of this activity Advance LTP towards Blue Book status Overview of LTP Goals of the protocol How LTP fits in with Internetworking / Bundle Protocol LTP Operation Comments on the specification To Do

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' SIS-DTN LTP Protocol Specification' - waldo


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

SIS-DTN

LTP Protocol Specification


Agenda
Agenda

  • Goals of this activity

    • Advance LTP towards Blue Book status

  • Overview of LTP

    • Goals of the protocol

    • How LTP fits in with Internetworking / Bundle Protocol

    • LTP Operation

    • Comments on the specification

  • To Do

    • Implementations exist (Burleigh, Farrell, Ramadas)

    • Write and execute test plan


Ltp overview
LTP Overview

  • LTP sits at roughly layer 2.5 in the ISO stack, providing optionally-reliable communications across a single data link ‘hop’

  • In the context of CCSDS, LTP is intended to run primarily over the CCSS Encapsulation service

  • For DTN / SSI, LTP serves as a ‘Convergence Layer’ for the Bundle Protocol, providing reliability for 1-hop communications

BP App

BP App

BP App

BP App

BP App

Optionally-reliable multi-hop space internetworking

BP App

BP

BP

Provides length field and allows LTP blocks to be efficiently packed into underlying frames.

LTP User

BP CLA

LTP User

BP CLA

LTP User

LTP User

Optionally-Reliable 1-HOP Communications

LTP

LTP

CCSDS Encapsulation

CCSDS Encapsulation

CCSDS Data Link (e.g. TC/TM, Prox-1, AOS)

CCSDS Data Link (e.g. TC/TM, Prox-1, AOS)

CCSDS RF, coding, and modulation

CCSDS RF, coding, and modulation


Ltp overview1
LTP Overview

  • LTP sits at roughly layer 2.5 in the ISO stack, providing optionally-reliable communications across a single data link ‘hop’

  • In the context of CCSDS, LTP is intended to run primarily over the CCSS Encapsulation service

  • For DTN / SSI, LTP serves as a ‘Convergence Layer’ for the Bundle Protocol, providing reliability for 1-hop communications

BP App

BP App

BP App

BP App

BP App

Optionally-reliable multi-hop space internetworking

BP App

BP

BP

Provides length field and allows LTP blocks to be efficiently packed into underlying frames.

LTP User

BP CLA

LTP User

BP CLA

LTP User

LTP User

Optionally-Reliable 1-HOP Communications

LTP

LTP

CCSDS Encapsulation

CCSDS Encapsulation

CCSDS Data Link (e.g. TC/TM, Prox-1, AOS)

CCSDS Data Link (e.g. TC/TM, Prox-1, AOS)

CCSDS RF, coding, and modulation

CCSDS RF, coding, and modulation


Ltp operation
LTP Operation

Fix me: after CP, EORP loss, retransmit.


The ccsds ltp red book
The CCSDS LTP Red Book

  • CCSDS Boilerplate

  • Overview

  • Service Specification (extracted from the RFC)

  • RFC5326 (Licklider Transmission Protocol)

    • Any comments on the specification?

    • http://tools.ietf.org/rfc/rfc5326.txt

  • Some LTP parameters are SDNVs (e.g. LTP session #s, checkpoint #s, report serial #s) and may be randomly selected integers – could be really really big (might want to restrict to --- a few bytes)

  • Note: PICS and MIB sections will cover the normatively referenced RFC

  • Security Extensions (RFC5327)? [authentication, cookies] – can omit if running BP over LTP? (use BAB instead)

  • Informative reference to SDNV RFC (pending)

  • Mapping LTP onto lower-layers (Link Service Adaptors for LTP – e.g. for Encap)

    • Issues w/ maximum LTP segment size to deal with underlying layer .e.g. TC (TC is 10 bits of length with no segmentation unless you use the MAP)

  • Options for multiple checkpoints when transmitting (prohibit?)

  • Asynchronously generated report segments (allow or deny these?)


Ltp segment format
LTP Segment Format

0

1

2

3

4

5

6

7

Version Number (0x01)

Segment Type Flags

Control-Byte

CTRL

EXC

Flag1

Flag0

Session ID

(Engine ID of source, session number chosen by sender)

Header

Header Extension Count

Trailer Extension Count

Header Extensions

Extensions

Segment Content

Trailer Extensions

Trailer


Flags
Flags

CTRL EXC Flag 1 Flag 0 Code Nature of segment

---- --- ------ ------ ---- ---------------------------------------

0 0 0 0 0 Red data, NOT {Checkpoint, EORP or EOB}

0 0 0 1 1 Red data, Checkpoint, NOT {EORP or EOB}

0 0 1 0 2 Red data, Checkpoint, EORP, NOT EOB

0 0 1 1 3 Red data, Checkpoint, EORP, EOB

0 1 0 0 4 Green data, NOT EOB

0 1 0 1 5 Green data, undefined

0 1 1 0 6 Green data, undefined

0 1 1 1 7 Green data, EOB

1 0 0 0 8 Report segment

1 0 0 1 9 Report-acknowledgment segment

1 0 1 0 10 Control segment, undefined

1 0 1 1 11 Control segment, undefined

1 1 0 0 12 Cancel segment from block sender

1 1 0 1 13 Cancel-acknowledgment segment to block sender

1 1 1 0 14 Cancel segment from block receiver

1 1 1 1 15 Cancel-acknowledgment segment to block receiver



Portion of block to be transmitted reliably.

Portion of block to be transmitted unreliably.

LTP Block

Transaction.request

Sending LTP User

Sending LTP Entity

Receiving LTP Entity

Receiving LTP User

SessionStart.indication

CP

RS

CP, EORP

GSArrival.indications

RS

InitialTransmission

Complete.indication

CP, EORP

RS

RedPartReception.

indication

TransmissionSession

Complete.

indication

RS Report Segment

CP Checkpoint

EORP End of Red Part


ad