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Masaki Hirabaru<[email protected]>
Tsukuba WAN Symposium 2005March 8, 2005
e-VLBI and End-to-End Performanceover Global Research Internet
Radio Telescopes
NICT Kashima Space Center 34m
Onsala Space Observatory 20m (left)
Perks 64m (right)Australia Telescope National Facility
MIT Haystack 18m
Shanghai25m
VLBI (Very Long Baseline Interferometry)de
lay
radio signal from a star
correlator
A/D clockA/D
Internet
clock
•e-VLBI geographically distributed observation, interconnecting radio antennas over the world
Large Bandwidth-Delay Product Network issue
ASTRONOMYGEODESY
~Gbps~Gbps
•Gigabit / real-time VLBI multi-gigabit rate sampling
A B
A
B
d
Analyzing Advanced TCP Dynamic Behavior in a Real Network(Example: From Tokyo to Indianapolis at 1G bps with HighSpeed TCP)
The data was obtained during e-VLBI demonstration at Internet2 Member Meeting in October 2003.
Throughput
RTT
Window Sizes
Packet Losses
Long-Distance Rover Control
15-30 minutes round trip delay
Image
Command
EarthMars
Long-Distance End-to-End Congestion Control
Merge (Bottleneck)
Overflow
Sender(JP)
Receiver(US)
Feedback
64Kbps x 200ms = 1600B ~ 1 Packet1Gbps x 200ms = 25MB ~ 16,700 Packets
200ms round trip delay
Advanced TCPs• Loss-Based
Reno, Scalable, High-Speed, BIC, RED, …
• Delay-BasedVegas, FAST
• Explicit Router NotificationECN, XCP, Quick Start, OQ
• Burstiness on Sender during Slow-Start
• Time Allowance to Feedback
RouterSwitch
1Gbps
100Mbps
b)
DeviceQueuing
Delay (µs)Capacity (Mbps)
Estimated Queue Size
(1500B)
Switch A 6161 100* 50
Switch B 22168 100* 180
Switch C 20847 100* 169
Switch D 738 1000 60
Switch E 3662 1000 298
Router F 148463 1000 12081
Router G 188627 1000 15350
* set to 100M for measurement
Measuring Bottleneck Queue SizesSwitch/Router Queue Size Measurement Result
Typical Bottleneck Cases
ReceiverSenderCapacit
y C
packet train lost packetmeasured packet
Queue Size = C x (Delaymax – Delaymin)
RouterSwitch
a)
Queue~100 Queue
~1000
VLANs
KwangjuBusan
2.5G
Fukuoka
Korea
2.5G SONET
KORENTaegu
Daejon
10G
1G (10G)1G
1G
Seoul XP
Genkai XP
Kitakyushu
Kashima
1G (10G)
Fukuoka Japan
250km
1,000km2.5G
JGN II
9,000km
4,000km
Los Angeles
Chicago
Washington DC
MIT Haystack
10G
2.4G
APII/JGN II
Abilene
Koganei
1G(10G)
Indianapolis
100kmbwctl server
Performance Measurement Platformfor High-Performance Scientific Data Transfer
10G
Tokyo XP /JGN II I-NOC
*Performance Measurement Point Directory http://e2epi.internet2.edu/pipes/pmp/pmp-dir.html
perf server
e-vlbi server
JGNII
10G
GEANT
SWITCH
7,000km
TransPAC
Pittsburgh
U of Tokyo
International collaboration to support for science applications
U. Hawaii
Summary
• Network Research Issues in ApplicationsLarge Bandwidth-Delay Product NetworksMultiple Data Sources / Data SynchronizingLoss Tolerance (5% Loss Allowance)Data Distributions (Multicasting)
• Operations / Engineering DevelopmentsObservatory (Measurement Data Collection)Performance Test PointsGlobal NOCs Collaborations
