10-Dec-2012-cesg-1

Presentation to ESTECNH Conference Centre, Nordwijkerhout, Netherlands

Hosted by ESA/ESTEC

8 April 2014

CCSDS Space Internetworking Services (SIS)

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SIS: We’re the End-to-End Internetwork (Purple Stuff)

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Space Internetworking Systems Area• The objective of the Space Internetworking Services (SIS) Area is to address the communications

services and protocols supporting end-to-end communications among applications, particularly where those communications may span multiple heterogeneous physical and data link technologies. Areas addressed by SIS include the networking infrastructure to support application-to-application communication onboard a single spacecraft, communications among multiple spacecraft, and communications between space-based applications and their counterparts on Earth and/or other planetary bodies.

• The SIS Area deals with communication services and protocols that are independent of specific link technology (as a lower layer bound) and independent of application-specific semantics (as an upper bound). Thus the SIS area covers essentially the network through application layers of the OSI reference model.

• SIS protocols use the underlying communication and infrastructure services provided by the Space Link Services (SLS) and Spacecraft Onboard Interface Services (SOIS) areas and any other onboard networks, and provide the networked connectivity needed by applications developed in other CCSDS areas such as Mission Operations and Information Management Services (MOIMS) and Spacecraft Onboard Interface Services (SOIS). The SIS services provide hardware-independent mechanisms for identifying end systems, and provide communications services that allow users to disregard whether the communication is over a single data link layer or over multiple hops. The suite of capabilities developed by the SIS Area accommodates all ranges of delay, interactivity, and directionality, although not all protocols are appropriate for all environments.

• The services provided by SIS protocols free applications from having to have intimate knowledge of the underlying communications protocols and mechanisms, and from having to know the physical location(s) of the entities with which they are communicating. This enables applications to focus on the application-specific protocols and interactions necessary to achieve their goals.

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SIS Area Relation to OSI Layers

OSI Layers*

Data Unit Layer Function

Host Layers

Data

Application Network process to application

PresentationData representation, encryption and decryption, convert machine dependent data to machine independent data

Session Interhost communication, managing sessions between applications

Segments Transport Reliable delivery of packets between points on a network.

Media Layers

Packet / Datagram Network

Addressing, routing and (not necessarily reliable) delivery of datagrams between points on a network.

Bit / Frame Data Link A reliable direct point-to-point data connection.

Bit Physical A (not necessarily reliable) direct point-to-point data connection.

*Adapted from the Wikipedia definitions.

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Why Internetworking?

• Lots of different physical layer technologies• Each designed / tuned for its particular local environment• Different data link addressing mechanisms

• Lots of different applications

• Internetwork layer provides: End-to-End delivery of datagrams• Applications don’t have to care where their peer are (same processor, link-

local, or 10 hops away) – just need to know their Network Address• ‘Global’ addressing mechanism (e.g. IP addresses)

Physical ALink A

InternetworkTransport

Application

PhyALinkAInternetwork

PhyBLinkB

PhyBLinkBInternetwork

PhyCLinkC

Physical ALink A

InternetworkTransport

Application

Network

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Internetworking and The Solar System Internet (SSI)

CL B CL B

BundleCL AConv. Layer A

ApplicationsBundle Bundle

Transport A Trans ANetwork A Network A Net A

Link A1 Link A1 Link An Link B1Phy A1 Phy A1 Phy An Phy B1Phy A2

Link A2 Link B1Phy B1

An internet A link-layer hop

Applications

• Internet Protocol suite (TCP/IP suite) works well in some space environments but not all:• IP suite assumes low-delay, constant connectivity

• Delay / Disruption Tolerant Networking (DTN) suite designed to work in space environments where IP suite doesn’t:• DTN routers can hold on to messages until an outbound link becomes available, e.g.• DTN can run as an internetwork directly over links (right side of figure) or on top of another suite

(e.g. TCP/IP) (left side of figure)

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The Current SIS Portfolio

CFDP

LTP

Voice and AudioCommunications

TCP/UDP/SCPS-TP

IPSec*

Internet Protocol (IPv4/IPv6)*

Space Packet

Robust Header Compression (ROHC)*

L3

L7

L5

L4

IP over CCSDS Link

Standardized through IETF

CCSDS Final RecommendationStandards track: draft/Revisions (pink)Experimental protocolDraft/Concept paper

AMS MotionImagery

EncapsulationPacket

BP (DTN)

BP NetworkManagement

BPRouting

BP Security

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The Current SIS Portfolio

CFDP

LTP

Voice and AudioCommunications

TCP/UDP/SCPS-TP

IPSec*

Internet Protocol (IPv4/IPv6)*

Space Packet

Robust Header Compression (ROHC)*

L3

L7

L5

L4

IP over CCSDS Link

AMS MotionImagery

EncapsulationPacket

BP (DTN)

BP NetworkManagement

BPRouting

BP Security

Low-Delay / Connected EnvironmentsHigh-Delay / Disrupted Environments

[ Many of the applications can function in both environments ]

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SIS Working Groups

• Motion Imagery and Applications• Interoperable (space-to-space and space-to-ground) video based

on industry standard codecs

• Voice• Interoperable (space-to-space and space-to-ground) voice based

on industry standard codecs

• Delay / Disruption Tolerant Networking• End-to-end internetworking for the space environment

• CFDP Revisions• Updates to the CFDP specification to better support operation over

a network layer; larger file sizes, etc.

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Motion Imagery and Applications

• Identify and agree upon use ofexisting digital video standardsand interfaces to providecommon interoperability ofvideo systems betweenspacecraft and from spacecraftto ground-based operationscenters

• Status• Completed Agency Reviews of Red Book. Currently documenting

proof of interoperability based mostly on use of standards in use by industry and used on the ISS

• Next Steps• Considering standardizing an implementation of bundle streaming

services for video operations

Spatial and Temporal motion imagery requirements

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Voice

• Voice and audio communications provides recommendations for interoperability between space agencies• Voice is considered mission critical for human space missions. • Due the international cooperation in space mission it is mandatory that different space

agencies can easily communicate between each other on the ground, to the spacecraft and with astronauts, taiconauts and cosmonauts in the spacecraft or during an EVA as well.

• Voice is also used for Satellite mission for communications with Ground Antennas and Space agencies.

• Status:• Finishing Blue book for Voice an Audio communications.• Preparing test to transfer Voice and Audio via DTN protocol.

• Next steps:• Interoperability testing for Blue book generation.• Prepare work for new digital voice matrixes.• Prepare work for Audio communication for missions beyond the Moon.

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Delay / Disruption Tolerant Networking (DTN)

• DTN provides ‘Internet-like’services for the spaceenvironment• DTN enables automated data handling: configure the network (provide

connectivity, schedules, etc.) and then let the network automatically deliver data to the destinations

• Status:• About to go to 3rd round of CCSDS Agency reviews on the Bundle Protocol and

Licklider Transmission Protocol (LTP is a reliable data link mechanism for use ‘under’ BP)

• Deploying on ISS for use by payloads and operations (file transfer)

• Next steps:• (DTN) Network Management, Security, Routing

CL B CL B

BundleCL AConv. Layer A

ApplicationsBundle Bundle

Transport A Trans ANetwork A Network A Net A

Link A1 Link A1 Link An Link B1Phy A1 Phy A1 Phy An Phy B1Phy A2

Link A2 Link B1Phy B1

An internet A link-layer hop

Applications

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CFDP Revisions

• CCSDS File Delivery Protocol (CFDP) is a protocol for automatic file transfer over space links, which may be characterized by long signal propagation delay and/or lengthy service outages.

• CFDP was standardized in 2007. CCSDS procedures require that standards be periodically reviewed and modified as necessary, or retired if no longer needed; this review is now under way for CFDP.

• Several enhancements to CFDP have been requested:• End-to-end file delivery notification (“Finished” PDU) for files sent in

Unacknowledged Mode to support CFDP over network (e.g. CFDP over BP)• Option to send limited metadata with each individual file data PDU (to make

individual PDUs more useful)• Option to send files larger than 4 Gigabytes.

• Status:• Consensus reached on Blue Book changes.

• Next steps:• Agency review of the revised CFDP Blue Book.• Plan for retrofitting implementations and testing interoperability.