Anthony Rushton. University of Manchester

Transcription

1 Application of VSI-E Anthony Rushton University of Manchester

2 VSI-E Transfer Protocol (VTP) This work attemps to comply with the draft VSI-E standard Rev. 2.7 VSI-E Tranfer protocol (VTP - version 1.0.P) implements VSI-E VTP is licendend under the MIT open source licence (approved by the OSI) VSI-E is NOT vapourware!! See for yourself, google: 'vsie twiki' RTP and RTCP channels used for control and data information VTP is design to be compatable with the existing VSI standard (legacy)

3 VSI-E Transfer Protocol (VTP) VTP runs in a standard Linux enviroment VTP can be scripted and parse parameters from BASH/CSH/etc. If you really like; VTP will accept parameters in XML format VTP performs simlar functions to VSI-S, i.e. FILE2NET IN2NET NET2FILE NET2OUT TVG2NET NET2TVR STDIN2NET NET2STDOUT VSI-E does not define the Data Transmision System (DTS)

4 Simulating an evlbi station In order to simulate evlbi station, pre-recorded telescope data was used JIVE has provided disk packs with recorded data (N07L2) from Effelsburg and Lovell Using the existing mark5 software (VSI-S) scans were coppied from JIVE to a mark5a disk pack at Jodrell.

5 Simulating an evlbi station In order to simulate evlbi station, pre-recorded telescope data was used JIVE has provided disk packs with recorded data (N07L2) from Effelsburg and Lovell Using the existing mark5 software (VSI-S) scans were coppied from JIVE to a mark5a disk pack at Jodrell. Effelsburg Lovell high performance PC Switch

6 Hardware independant To demostrait a trans-atlantic evlbi fringe under the VSI-E framework Do this using: Mark5 high performance pc FPGA etc. VSI-E JBO Haystack

7 Hardware independant To demostrait a trans-atlantic evlbi fringe under the VSI-E framework Do this using: Mark5 high performance pc FPGA etc. VSI-E JBO Haystack

8 Hardware independant To demostrait a trans-atlantic evlbi fringe under the VSI-E framework Do this using: Mark5 high performance pc FPGA etc. VSI-E JBO Haystack

9 VTP throughput test over lightpath Glownet Bossnet

10 TCPdump packet inspection TCPdump is a comon networking debug tool, developed by Lawrence Berkeley Laboratory Network Research Group TCP or UDP packets from a specified interface and network port are logged Throughput of the data channel (RTP packets) was measured: ~200 Mbps!! On a 1 Gbps LightPath? The blue line represents throughput

11 TCPdump pack inspection TCPdump is a comon networking debug tool, developed by Lawrence Berkeley Laboratory Network Research Group TCP or UDP packets from a specified interface and network port are logged Throughput of the data channel (RTP packets) was measured: ~200 Mbps!! On a 1 Gbps LightPath?

12 Why are we not achieving line rate? The application is not sending packets at the correct rate Application (VTP) issue: This could be due to a bug in VTP version 1.0.P More likely a user configuration fault Hardware issue: VSI-E is medium independant You must check that its not your hardware!

13 Supermirco motherboard Raid drive Gigabit ethernet

14 Supermirco motherboard Raid drive Gigabit ethernet

15 UDP NIC to NIC: Application buffer UDP transfer tests between directly connected NIC's The application transmitted UDP at line rate (~950 Mbps) The buffer size of the receive host was varied from 65 KB to 300 KB Packet loss was observed when the receive buff was less than ~ 230 KB

16 Why are we not achieving line rate? The application is not sending packets at the correct rate Application (VTP) issue: This could be due to a bug in VTP version 1.0.P More likely a user configuration fault Hardware issue: Network issue: VSI-E is medium independant You must check that its not your hardware! Local area network is incorrectly configure Its your LightPath it has happen

17 Iperf tests TCP bandwidth test between Manchester and Chicago Iperf tested the maximum bandwidth Multiple packet losses throughout the test TCP congestion control reduced the throughput rate on a dedicated light path TCP transfer from Manchester to Chicago

18 Constant packet loss when running at line rate UDP transfer was tested in the opposite direction: Manchester to Chicago The receive buffer was set to 300 KB Once again the application was losing a large frication of packets ( > 1 % ) The test was performed for a longer period of time (~ 30 hours)

19 Constant packet loss when running at line rate A constant loss of at least 3000 packets per 50,000,000 sent (0.001%) in every test.

20 The application sends 50 million packets per test Sender Network layer UDP application Send 50,000,000 packets per test Receiver UDP application socket layer socket layer UDP UDP IP IP NIC Cisco 7600 UKLight Across the network NIC

21 The application reports 3000 packets have been lost per test (i.e. per 50 million) Receiver Sender UDP application Network layer UDP application socket layer socket layer UDP UDP IP IP NIC Cisco 7600 UKLight Across the network NIC

22 The snmp interface into the Cisco 7600 Switch, records 50 million packets receive every test Receiver Sender UDP application Network layer UDP application socket layer socket layer UDP UDP IP IP NIC Cisco 7600 UKLight Across the network NIC

23 The snmp interface out of the Cisco 7600 Switch, records 49,998,600 packets sent every test Receiver Sender UDP application Network layer UDP application socket layer socket layer UDP UDP IP IP NIC Cisco 7600 UKLight Across the network NIC

24 800 Mbps works! UDP transfer test at 800 Mbps The application receives every packet (with a slight exception) All the packets are therefore received by the switch No packets are lost by the switch

25 1 Gbps from Jodrell to Chicago ~940 Mbps for 3 days >20 Billion packets have been transmitted Over 240 Terabytes of data Only four packets had been lost!!

26 Summary The UKLight path between Manchester and Chicago now works Our local switch issues have been fixed Our data transmission system is not a bottle neck We need to look at VTP's transmission rate Once Chicago is connect to Haystack, we will make a Lovell Effelsburg fringe using VSI-E

27 The End