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Addressing

Profile • SpaceWire supports three types of addressing: Path (Physical) Addressing, Logical Addressing, and Regional Addressing. JAS uses regional addressing because it provides the greatest flexibility to create scalable networks. Regional addressing uses a two-byte scheme where the first byte identifies the router and the second byte identifies the endpoint address connected...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Transport > Addressing

Communication Profile

Profile • The Communication Profile defines standard interfaces for facilitating communication between RP, CH, and PS nodes within a JAS system. The Communication Profile focuses primarily on communication between payload applications. It leverages industry standards to support network-based communication using serial interfaces. A common set of communication protocols for space applications has...

Communication Profile

Functional Description

Profile • The Communication Profile defines standard methods for transferring data between two JAS nodes. This includes the use of protocols and packet formats by hardware and software. Applications become portable and reusable by using layered communication architecture. The applications should be agnostic to the choice of physical interconnect technology, which allows...

Communication Profile > Functional Description

Interconnect Technologies

Profile • This profile describes the interconnect technologies supported by JAS. Each interconnect will be comprised of three layers based on the RapidIO standard: the Logical Layer; the Transport Layer; and the Physical Layer. The figure below shows a mapping of the interconnect layers to the OSI layers. The Application Layer is...

Communication Profile > Interconnect Technologies

JAS CCSDS SOIS

Profile • The JAS communication architecture is based on the Consultative Committee for Space Data Systems (CCSDS) Spacecraft Onboard Interface Services (SOIS) reference communication architecture. SOIS describes a layered architecture that allows applications to be abstracted from the specific communication data links. The SOIS architecture describes four layers: the Application Layer, the...

Communication Profile > Functional Description > JAS CCSDS SOIS

JAS Efficient Exchange Protocol

Profile • The JAS Efficient Exchange Protocol (JEEP) is a best-effort packet transmission protocol that can be used to send messages between applications over a SpaceWire data link. JEEP is similar to the JRDDP protocol in that provides a segmentation capability to promote fairness between all applications needing to communicate on the...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Logical > JAS Efficient Exchange Protocol

JAS Packet Protocol

Profile • The JAS Packet Protocol (JPP) provides the capability to send a single JAS Packet over a SpaceWire data link. JPP is just an encapsulation of a JAS Packet within a SpaceWire packet. Even though it is classified as a SpaceWire protocol, there are no QoS functions provided apart from those...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Logical > JAS Packet Protocol

JAS Reliable Data Delivery Protocol

Profile • The JAS Reliable Data Delivery Protocol (JRDDP) is a reliable packet transmission protocol that can be used to send messages between applications over a SpaceWire data link. It is based on a protocol created by the National Aeronautics and Space Administration (NASA) at the Goddard Spaceflight Center in Greenbelt, Maryland,...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Logical > JAS Reliable Data Delivery Protocol

Memory Access Service

Profile • The Memory Access Service is used to asynchronously read and write to memory-based devices across a network. The Memory Access Service is based on the CCSDS SOIS Memory Access Service and provides a layer of abstraction between applications and memory-based devices. It provides a common API for applications to use...

Communication Profile > Subnetwork Services > Memory Access Service

Multicast/Broadcast

Profile • SpaceWire doesn’t inherently support a multicast or broadcast capability. There is a time-code distribution function but it is limited in the amount of user information that can be distributed. An approach has been developed for a broadcast capability through custom router and endpoint modifications. It uses a set of dedicated...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Transport > Multicast/Broadcast

Network Discovery

Profile • When probing for routing switches, early network discovery techniques typically relied on each routing switch’s configuration port to respond to identification requests to confirm the routing switch’s presence. A request packet was typically dispatched to the configuration port, and a response packet provided confirmation of existence. This same request/response approach...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Transport > Network Discovery

Networks

Profile • Each JAS node should contain a SpaceWire Router per the SMAC Profile which allows for extensive scaling of the network. A network is made up of a number of links, nodes (endpoints) and routing switches. Links provide the means for passing packets from one node to another. Nodes can be...

Communication Profile > Interconnect Technologies > SpaceWire Interconnect > SpaceWire Transport > Networks

Packet Service

Profile • A packet service is used to send messages between applications. JAS assumes that each processing element has one packet service for each packet format that is defined. In order to promote reuse, a layered architecture is used whereby applications are abstracted from the packet format details. The packet service contains...

Communication Profile > Subnetwork Services > Packet Service