May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 1 NRAO – Westford e-VLBI Trial Chester Ruszczyk / Walter Brisken MIT Haystack / NRAO

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 2 Agenda Trial Description Trial Results Network Performance Steps To Achieve Success –May 21 st Trial –Others ?

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 3 Trial Description Real-time e-VLBI Trial –May 7 th 12 UTC – 16 UTC –X band Antennas –VLA single dish –Westford Correlator –Haystack Mode –32 Mbps single channel

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 4

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 5 Trial Results Auto-correlation –Westford Failed to get auto-correlation with VLA –Issue was network performance –Socorro to Haystack No fringes were attempted to be detected

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 6 Network Performance Link from Socorro to NYC –~42Mbps Link from Socorro to Haystack –32.7 Mbps MAX. Drops in performance on the sending machine –Failed to maintain required data rate ~34Mbps

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 7 Network Performance Potential source of the performance failure –Backbone between NYC - Haystack –Rate limiting Socorro and Albuquerque 35Mbps maximum May be limiting TCP performance for long haul networks –Investigating

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 8 Next Steps Isolate the network performance between the backbone and the end systems. Quantify the performance from the Mark5A at the VLA to Haystack –This can be a noise source being sent from the VLA to Haystack and decoded at the correlator –Implementing Web100 based kernel to analyze the end-systems Determine why 42Mbps was achievable between VLA and NYC but not beyond. –Verify Performance from Denver, Chicago, NYC to Haystack

May 15, 2007U.S. VLBI Technical Coordination Meeting, Socorro NM 9 Next Steps (cont) Install Network Diagnostic tools on Mk5s –Quantify end systems and –end-to-end characteristics If we are unable to sustain the required TCP traffic through testing –Use constant bit rate UDP based protocol May 21, attempt the second test. VLA network connection extended beyond May. –Other test dates?