1. Trial on the Efficient Use of Trunk Communcation Lines for VLBI in Japan Noriyuki Kawaguchi NATIONAL Astronomial Observatory,Japan eVLBI Workshop 2008.6.17@Shanghai Observatory

2. Contents (1) 10GbE connection with variable bit rate Kashima 34m and Koganei 11m (2) L1 on-demand connection Yamaguchi 32m and Tsukuba 32m (3) Link Aggregation of multiple GbE links Tomakomai 11m access link

3. Test Fields in Japan Tomakomai 11m Hokkaido University Sapporo Kashima 34m Koganei 11m L1 on-demand Yamaguchi 32m Tsukuba 32m GbE Aggregation 10GbE connection

4. 10GbE Connection D Port ＃１ C Port ＃１ D Port ＃ 2 C Port ＃ 2 D Port ＃ 3 C Port ＃ 3 D Port ＃ 4 C Port ＃ 4 VSI(DIM,2048Mbps) ADS-1000 VDC-100F VSI(DOM,2048Mbps) VSI(DIM,2048Mbps) ADS-1000 VDC-100F VSI(DOM,2048Mbps) VSI(DIM,2048Mbps) ADS-1000 VDC-100F VSI(DOM,2048Mbps) VSI(DIM,2048Mbps) ADS-1000 VDC-100F VSI(DOM,2048Mbps) Cont. CPU ＧｂＥ １０ＧｂＥ １０Ｇ－ＢＡＳＥ－ＬＲ １．３ μm １０ＧｂＥ Unit ＧｂＥ Network CPU ＳＩＮＥＴ３ （ Comm. & Cont. ） （ Local Control ） ＣＴＬＰ （ Cont. Port ） ＣＨＬＰ （ Comm. POrt ） 2.048 Gbps x 4 I/O ports 10GbE Port

5. Photo 10GbE Unit From Kashima From Koganei 11m 2GHz A/D Real time Correlator 10 GbE Analyzer

6. Bit Rate Control in congestion Bit Rate Down to 2Gbps Bit Rate Down to 1Gbps Bit Rate Down to 0.5Gbps Time Code Not detected Time Code Partially detected Time Code completely detected. Possible to start correlation

7. Packet Arrival Time Records No Congestion Under heavy congestion Many packets are stocked in memory and suddenly released in very short time. New function to pick up the suddenly released packets are now considered.

8. Data Flow Monitoring

9. L1 on-demand connection

10. Efficient Use of limited Resource We can enjoy long time and wide bandwidth on Saturday and Sunday!

11. L1 on-demand connection (1)Reservation (30minutes before observation) 1)Request to the connection time 2)Request to the bandwidth 3)Negotiation for time and bandwidth 4)Report for the time and bandwidth granted (2)Telescope Operation (3)Real time Fringe Monitoring

12. First Success in real time observation on L1 on-demand connection June 12, 2008 Yamaguchi 32m Tsukuba 32m X-band 2Gbps

13. Link Aggregation Technique Binding cheap low-bit-rate links And Getting a extremely high bit rate

14. Link Aggregation of multiple GbEs Foundry MLX-4 Foundry MLX-4 ADS-1000 BW=512MH ｚ （ 512-1024MHz ） VOA-200 SINET3 A/D converter of 2.048-Gbps sampling 10GbE Unit Hope to carry 2Gbps payload through three GbE connections To Mitaka, Tokyo Hokkaido University in Sapporo 11m Telescope in Tomakomai GbE x 3 Connections with low bit rate links in cheap cost The link aggregation test will start in this summer.

15. Space Light Path 光空間伝送 Town, City Observatory Trunk Communication Line Laser Beam Tracking Mirror developed 10-Gbps, 10-km connection is a target.

16. Compact Opt TX/RX system

17. Conclusions Efficient Use of Communication Line –shared use of 10GbE line successfully demonstrated in the test between Kashima- Koganei –L1 on-demand connection successfully performed in the first test between Ymaguchi and Tsukuba –Link Aggregation to be achieved in 2008 –Space Light Path Connection To be tested in Usuda 64m site