SIS_DTN 1 SIS-DTN LTP Protocol Specification May 2010

SIS_DTN 2 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 May 2010

SIS_DTN 3 BP App 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 May 2010 LTP User BP CLA LTP CCSDS Encapsulation CCSDS Data Link (e.g. TC/TM, Prox-1, AOS) CCSDS Encapsulation LTP Optionally-Reliable 1-HOP Communications Provides length field and allows LTP blocks to be efficiently packed into underlying frames. CCSDS RF, coding, and modulation BP BP App LTP User BP CLA BP BP App Optionally-reliable multi-hop space internetworking

SIS_DTN 4 BP App 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 May 2010 LTP User BP CLA LTP CCSDS Encapsulation CCSDS Data Link (e.g. TC/TM, Prox-1, AOS) CCSDS Encapsulation LTP Optionally-Reliable 1-HOP Communications Provides length field and allows LTP blocks to be efficiently packed into underlying frames. CCSDS RF, coding, and modulation BP BP App LTP User BP CLA BP BP App Optionally-reliable multi-hop space internetworking

SIS_DTN 5 LTP Operation May 2010 Fix me: after CP, EORP loss, retransmit.

SIS_DTN 6 The CCSDS LTP Red Book CCSDS Boilerplate Overview Service Specification (extracted from the RFC) RFC5326 (Licklider Transmission Protocol) Any comments on the specification? 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?) May 2010

SIS_DTN 7 LTP Segment Format May 2010 Version Number (0x01) Segment Type Flags Session ID (Engine ID of source, session number chosen by sender) Header Extensions Segment Content Trailer Extensions Header Extension CountTrailer Extension Count Header Trailer Control-Byte Extensions CTRLEXCFlag1Flag0

SIS_DTN 8 Flags May 2010 CTRL EXC Flag 1 Flag 0 Code Nature of segment Red data, NOT {Checkpoint, EORP or EOB} Red data, Checkpoint, NOT {EORP or EOB} Red data, Checkpoint, EORP, NOT EOB Red data, Checkpoint, EORP, EOB Green data, NOT EOB Green data, undefined Green data, undefined Green data, EOB Report segment Report-acknowledgment segment Control segment, undefined Control segment, undefined Cancel segment from block sender Cancel-acknowledgment segment to block sender Cancel segment from block receiver Cancel-acknowledgment segment to block receiver

SIS_DTN 9 Backups May 2010

SIS_DTN 10 May 2010 Sending LTP Entity Receiving LTP Entity Sending LTP User Receiving LTP User RS CP, EORP RS CP RSReport Segment CPCheckpoint EORPEnd of Red Part Transaction. request SessionStart.indication GSArrival.indications RedPartReception. indication TransmissionSession Complete. indication CP, EORP RS InitialTransmission Complete.indication LTP Block Portion of block to be transmitted reliably. Portion of block to be transmitted unreliably.