JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester The EVN-NREN Project Richard Hughes-Jones The University of Manchester

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester uRadio Astronomy UDP/IP Streaming 500 Mbit/s uiGrid2002 and ER2002 uBE & LBE Qos on GÉANT Backbone uWeb site

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester iGRID2002 Radio Astronomy VLBI Demo. uWeb based demonstration sending VLBI data A controlled stream of UDP packets Mbit/s on the production network Man  Amsterdam 32 bit words bits vertical Bit Stream ~ 7.1 UDP Packets / Data Track Frame Timestamp Data Data Track Frame

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester European Topology: NRNs, Geant, Sites SuperJANET4 CERN iGrid 2002 Manchester Jodrell SURFnet JIVE

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester The Works: n bytes Wait time time  Raid0 Disc UDP Data Raid0 Disc RingBuffer TCP Control Web Interface

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Receiving Packets Time Incoming packet ids Move 6 Continue with 7 uPackets have Header with packet id + Data Put header directly into control area Put data directly into ring buffer No extra copy uAssume UDP packet arrive in order none lost Deposit data into next consecutive slot uInspect Header Move data onward to correct location Record: The received inter-packet spacing 1-way delay

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester UDP Throughput on the Production WAN Manc-UvA SARA 750 Mbit/s SJANET4 + Geant + SURFnet 75% Manchester Access link Manc-UvA SARA 825 Mbit/s

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Service uIP transport Can be routed over the production networks uSDH Less overhead cf IP Will need ethernet framing to get into the PC Future high-rate dedicated HW

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Traffic Profile uEVN observing (now) 25 day runs 24 hrs/day Future more flexible Telescope regularly switches to a calibration source Same data rate for many hours uTraffic is continuous uUltimate goal: real-time from telescope uTests: sending from disk files

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Transport (1): uUDP/IP Demonstrated at iGrid2002 & ER Mbit/s 1500 Byte packets 20 µs spacing OK provided packet loss small Backbones Surfnet, SuperJANET and Dante OK (for now) uTCP/IP Basic problem – protocol takes packet loss as congestion signal MAN  Ams For BW of1Gbit, if loose 1 frame, takes 94s to run at full rate uPacket Re-ordering Already seen in demos Normally 1 packet but have seen 2 (or more) at high rate Can cope with this.

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Transport (2): uDelay / Jitter Not very important if O 10ms variation Different telescopes have different network delays Will buffer data at the receiver uSingle/Multiple Flows Observing rate 1024 Mbit/s = User data rate + telescope overhead + Network overhead Ethernet frame, IP, UDP, RAST Gigabit NIC wire rate 1 Gbit/s Use of 2 GigEth interfaces into loacl router then 2.5G SDH

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Traffic QoS Classes on GÉANT Backbone uNormal Traffic uNormal Traffic + uLess Than Best Effort 2.0 Gbit/s uNormal Traffic + uRadio Astronomy Data 500 Mbit/s uNormal Traffic + uRadio Astronomy Data + uLess Than Best Effort 2.0 Gbit/s Max Throughput on 2.5 G PoS

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Some Measurements made during ER2002 uManchester – SuperJANET Access link 1 Gbit/s u500 Mbit UDP/IP uIncoming depressed

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Some Measurements made during ER2002 uDante Backbone uUK-NL link Incoming at NL

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Some Measurements made during ER2002

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Latency Histograms No LBE2.0 Gbit LBE UK  DE

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Throughput No LBE2.0 Gbit LBE UK  DE

JIVE VLBI Network Meeting 15 Jan 2003 R. Hughes-Jones Manchester Packet re-ordering u20 µs Transmit packet spacing 10,000 sent uDifferent behaviour for small packets uStill some re-ordering at 40 µs spacing ~100 for 100 bytes 20 for >1000 bytes