Integration of VSI-E into Operation Systems
Chester Ruszczyk
chester@haystack.mit.edu
Alan Whitney
awhitney@haystack.mit.edu
4th e-VLBI Workshop, Sydney, Australia
Wed. July 13, 2005
Agenda
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VSI-E History / Characteristics
VSI-E Modes
VSI-E Tasks
Conclusion
VSI-E History
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VSI-E proposed to simplify the exchange of
data between the VLBI systems of different
countries.
e-VLBI Workshop Dwingeloo 2003
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First discussion on VSI-E
Goals
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Efficient transport mechanism
Standard protocols
Internet-friendly transport
VSI-E History
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Goals (cont)
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Scalable Implementation
Ability to transport individual data-channel
streams as individual packet streams
Ability to make use of multicasting
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to transport data and/or control information in an efficient
manner
could be used in the future for support of distributed
correlation
VSI-E History
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RTP proposed for transport of VSI-E data
‰ RTP has wealth of implementation and
operational experience
‰ RTP seen as internet-friendly by the network
community. Attention to:
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Efficiency,
Resource constraints,
Scaling issues
VSI-E Documentation and Software
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VSI-E Draft release 2.7, January 30, 2004
‰ http://evlbi.haystack.mit.edu/twiki/pub/EVLBI/Web
Docs/VSI-E-2-7.pdf
Reference implementation library and application (vtp)
release 1.0, October 5th, 2004
‰ http://evlbi.haystack.mit.edu/twiki/bin/views/EVLBI
‰ Linux, BSD - based
VSI-E Characteristics - RTP
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Framework for transporting real-time data
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Timing and synchronization
Merging, bridging, and translation support
Application-specific control data
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e.g. PDATA, time, data collection parameters, antenna
pointing, system temperature
Real-time / non-real time transfers
Transport protocol independent
Multicast support
Data rates up to 100Gbps
VSI-E Characteristics (RTCP)
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RTP Control Protocol
Monitors network’s real-time performance
Statistics collected from receivers
Information delivered to
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Senders
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Network management
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adapt to prevailing conditions
identifies faults, provisioning problems
Adaptive, bandwidth-limited design
VSI-E Architecture
VSI-E Modes
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Real-time
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Buffer to buffer
Non-Real Time
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File to File or Disk
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“File” is used as temporary storage
Disk to Disk or File
Pseudo Real Time
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Disk to Buffer
File to Buffer
Pseudo Real-Time Operation
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Ability to take stored data (disk or file mode)
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Create connection to Correlator
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Source Stations
Network attached storage on the network
Storage Depot
Correlate the data
File2net – Net2In
Disk2net – Net2In
Advantageous
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Demos
Disks
VSI-E Tasks
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Draft
RTP Profile for IETF
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E-VLBI Specific
Transport Protocol
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Guidelines and profiles
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Various transport alternatives.
Conversion into VSI-E format
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VTP -1.0.H (Mark5 specific)
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Development of efficient translation modules
Development of efficient packetization algorithms
Support for different transport protocols inherent in application,
but not dynamic
Conclusion
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VSI-E Testing
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Test bed between
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VSI-E planned to be demonstrated
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Super Computing 05 (November)
Participants: Europe, Japan, US
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Haystack and Kashima
K5 Source to Mark5 Correlator
Transport protocol evaluation (UDP/TCP)
Correlated at Haystack
Fringes sent live to Seattle
Integration to resource allocation scheme