Office NameOffice NameGoddard Space Flight Center
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Proposed SCaN-Cx Interface Study Approach
Dave IsraelAugust 24, 2007
Office NameOffice NameGoddard Space Flight Center
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Study Subject
• Fundamental question: “Should the baseline plan for SCaN support of Cx ISS phase include a service interface to the ground stations at the link layer or network layer?”
• Two basic options for initial Cx support: One uses SLE, one does not.– Out of scope of this initial activity
• AOS/HDLC discussions• Use of IP discussions• LDPC
• Requirements are based on SCaN-Cx MOA and its referenced documents
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Specific Trade Study
• Only focus on items that are different between the two options• Small team
– Bring in technical expertise as needed for testing, demonstrations, or review
– Use existing work from other activities for starting points and work with single points of contact for more information
– Maintain alignment with CNST, SCIP, SNIS, Standards, and other related activities
• Provide updates and receive concurrence from SCaN (J. Rush & A. Hooke) and SCIP (R. Miller & J. Hudiburg) throughout the activity
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Deliverables and Schedule
• Assumptions used for study• Itemized documentation of each option’s ability to meet Cx requirements• Performance study results• Demonstration of both options performed with GSFC CSTL and JSC• Delta cost between two options
– Implementation– Operations– Future expansion
• Documentation of role and responsibility allocation between Cx and SCaN for each option
• Risk Identification and mitigation strategies• List of open issues• Pros/Cons/Recommendations
Final Report Goal: November 30, 2007
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Next Steps
• Collect questions that need to be answered• Collect assumptions• Start forming teams/connections for different activities• Define reference designs for baseline
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Expected Subjects
• SLE performance impacts• Security implications• Service management implications• Shift of Roles and Responsibilities• Implementation costs• Operations costs • Future upgrade costs• Interoperability considerations• Demonstrations and tests including data flows with JSC
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Discussion Questions
• Is this an acceptable course of action?• What are the schedule drivers?
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Reference Diagrams
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SCaN-Cx Interfaces Diagram
SCaN CxVehicles
RFCxGround
Elements
Service Management
Data Transfer
Tracking & Navigation
Cx Ground Element Intercommunications
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???
Simplified Option Diagram – Link Layer Interface
MS
GS
AF
KSCFDF
SN
NISN
?
SLE
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???
Simplified Option Diagram – Network Layer Interface
MS
GS
AF
KSCFDF
SN
NISN
?
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Direct IP
IP over SLESide by Side Comparison
(PHY)
(IP Forwarder)
(PHY)
IP
(LNK) (LNK)
EndUser
(App.)
UDP
IP
End UserInternal Node
(LNK)
IP
UDP
(PHY)
(App.)
(LNK)
(PHY)
ControlCenter
Internal NodeControlCenter
AOS
IP
(IP Forwarder)
HDLC
(AOS Forwarder)
(RF)
AOS
(RF)
AOS
Earth GroundStation
HDLC
SLE
(LNK)(LNK)
IP
TCP
SLE
IP
TCP
(PHY) (PHY)
(PHY)
(IP Forwarder)
(PHY)
IP
(LNK) (LNK)
(App.)
UDP
IP
(LNK)
IP
UDP
(PHY)
(App.)
(LNK)
(PHY)
(IP Forwarder)
IP
(LNK)(LNK)
(PHY) (PHY)
(IP Forwarder)
(RF) (RF)
AOS
HDLC
AOS
HDLC
IP
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Direct IP
IP over SLE
Cx-SCaN Basic Functional Allocations
(PHY)
(IP Forwarder)
(PHY)
IP
(LNK) (LNK)
EndUser
(App.)
UDP
IP
End UserInternal Node
(LNK)
IP
UDP
(PHY)
(App.)
(LNK)
(PHY)
ControlCenter
Internal NodeControlCenter
AOS
IP
(IP Forwarder)
HDLC
(AOS Forwarder)
(RF)
AOS
(RF)
AOS
Earth GroundStation
HDLC
SLE
(LNK)(LNK)
IP
TCP
SLE
IP
TCP
(PHY) (PHY)
(PHY)
(IP Forwarder)
(PHY)
IP
(LNK) (LNK)
(App.)
UDP
IP
(LNK)
IP
UDP
(PHY)
(App.)
(LNK)
(PHY)
(IP Forwarder)
IP
(LNK)(LNK)
(PHY) (PHY)
(IP Forwarder)
(RF) (RF)
AOS
HDLC
AOS
HDLC
IP
Workstation
SLEG
ateway
Processor
RFRF
Router SLEGateway
Router
Workstation
Router
Processor
RFRF
Router
Router
Router
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Common to Both Options
• RF Modulation and Coding• Link layer framing• Service Management interfaces• Tracking and navigation• Time services• Line outage recording