Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Networking for ATLAS Remote Farms
Richard Hughes-JonesThe University of Manchester
DataGrid WP7 – Dante Tests on the GÉANT CoreEnd-2-End Measurements from the 4th Year VLBI Project at ManchesterNew TCP stacks – the effect on throughputSome Simple Network Tests CERN-Manchester
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
DataGrid WP7 – Dante Tests on the GÉANT Core
Set-up
Supermicro PC in: London GEANT PoP Amsterdam GEANT PoP
Smartbits in: London GEANT PoP Frankfurt GEANT PoP
Long link UK-SE-DE2-IT-CH-FR-BE-NL
Short Link UK-FR-BE-NL
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Tests GÉANT Core: UDP throughput
UDP Throughput London-Amsterdam Available BW to packet on wire Then 1/t Wire rate 998 Mbit/s
for packets > 1400 bytes
Packet Loss None for large packets
Dips in BW lined to packet loss SysKonnect NIC int. per packet CPU load important
uk-nl_20tg4-hs-w100_01Oct03
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0 5 10 15 20 25 30 35 40Spacing between frames us
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v W
ire r
ate
Mbi
ts/s
50 bytes 100 bytes 200 bytes 400 bytes 600 bytes 800 bytes 1000 bytes 1200 bytes 1400 bytes 1472 bytes
0102030405060708090
100
0 5 10 15 20 25 30 35 40Spacing between frames us
% P
acke
t los
s
50 bytes 100 bytes 200 bytes 400 bytes 600 bytes 800 bytes 1000 bytes 1200 bytes 1400 bytes 1472 bytes
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Tests GÉANT Core: Packet re-ordering
Effect of Packet size London-Amsterdam Packets at 10 µs – line speed 10,000 sent Packet Loss ~ 0.1%
Re-order Distribution
Packet re-order uk-nl 10,000 BE sent wait 10 us 01 Oct 03
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0 500 1000 1500Packet size bytes
Out
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rder
% 0
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1400 1401 1402 1403 1404Packet size bytes
Ou
t o
f o
rde
r %
Packet re-order uk-nl 10,000 sent wait 10 us
0
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400
500
0 1 2 3 4 5 6 7 8 9Length out-of-order
No.
Pac
kets 1400 bytes
1401 bytes
1402 bytes
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Tests GÉANT Core: Packet re-ordering
Effect of LBE background Amsterdam-London BE Test flow Packets at 10 µs – line speed 10,000 sent Packet Loss ~ 0.1%
Re-order Distributions:
UDP 1472 bytes NL-UK-lbexxx_7nov03
02468
101214161820
2 2.2 2.4 2.6 2.8 3 3.2Total Offered Rate Gbit/s
% O
ut o
f ord
er
hstcpStandard TCP line speed90% line speed
Packet re-order 1472 bytes uk-nl 21 Oct 03 10,000 sent wait 10 us
020000400006000080000
100000120000140000160000180000200000
1 2 3 4 5 6 7 8 9Length out-of-order
No.
Pac
kets
0 % lbe
10 % lbe
20 % lbe
30 % lbe
40 % lbe
50 % lbe
60 % lbe
70 % lbe
80 % lbe
Packet re-order 1400 bytes uk-nl 21 Oct 03 10,000 sent wait 10 us
0500
100015002000250030003500400045005000
1 2 3 4 5 6 7 8 9Length out-of-order
No.
Pac
kets
0 % lbe
10 % lbe
20 % lbe
30 % lbe
40 % lbe
50 % lbe
60 % lbe
70 % lbe
80 % lbe
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Tests GÉANT Core: Packet Jitter Amsterdam-London BE Test flow Packet spacing 80 µs
IPPremium Test flow
Flow: BE Background: none
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0 20 40 60 80 100 120 140
Latency us
Fre
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Flow:IPP Background: none
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0 20 40 60 80 100 120 140Packet Jitter us
Fre
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ency
Flow:BE Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
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Packet Jitter us
Fre
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BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
flow:IPP Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
0
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20000
30000
40000
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60000
0 20 40 60 80 100 120 140Packet Jitter us
1-w
ay l
aten
cy u
s
IPPremium Test flow + Background
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Tests GÉANT Core: 1-way Delay Amsterdam-London IPPremium Test flow Packet spacing 80 µs
BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
BE Test flow + Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
Flow:IPP Background: none
11220
11240
11260
11280
11300
11320
11340
0 2000 4000 6000 8000 10000Packet No.
1-w
ay la
tenc
y us
Flow:BE Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
11000112001140011600118001200012200124001260012800
0 2000 4000 6000 8000 10000Packet No.
1-w
ay la
tenc
y us
Flow:IPP Background: 60% BE 1.4Gbit + 40% LBE 780Mbit
1120011250113001135011400114501150011550116001165011700
0 2000 4000 6000 8000 10000Packet No.
1-w
ay la
tenc
y us
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
VLBI Project: Test Topology
SuperJANET4
Jodrell
Manchester
SURFnet
JIVEDwingaloo
Adam MathewsSteve O’TooleUniv of Manchester
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Gnt5-DwMk5 11Nov03-1472 bytes
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% P
acket
loss
Gnt5-DwMk5
DwMk5-Gnt5
Manchester to Dwingeloo 2.0G Hz Xeon 1.2 GHz PIII
Re-ordering vs Offered Load
VLBI Project: Throughput
Gnt5-DwMk5 11Nov03/DwMk5-Gnt5 13Nov03-1472bytes
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Recv W
ire r
ate
Mbits/s
Gnt5-DwMk5
DwMk5-Gnt5
Gnt5-DwMk5 11Nov03 1472 bytes
020406080
100
0 5 10 15 20 25 30 35 40Spacing between frames us
% K
erne
l S
ende
r
Gnt5-DwMk5 11Nov03 1472 bytes
020406080
100
0 5 10 15 20 25 30 35 40Spacing between frames us
% K
erne
l R
ecei
ver
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
1472 byte Packets man -> JIVE FWHM 22 µs (B2B 3 µs )
VLBI Project: Jitter & 1-way Delay
1472 bytes w=50 jitter Gnt5-DwMk5 28Oct03
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Jitter us
N(t
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1472 bytes w=50 jitter Gnt5-DwMk5 28Oct03
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0 20 40 60 80 100 120 140
Jitter us
N(t
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1472 bytes w12 Gnt5-DwMk5 21Oct03
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2000 2100 2200 2300 2400 2500 2600 2700 2800 2900 3000Packet No.
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us
1472 bytes w12 Gnt5-DwMk5 21Oct03
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0 1000 2000 3000 4000 5000Packet No.
1-w
ay d
elay
us
1-way Delay – note the packet loss (points with 0 –way delay)
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Aggregated Variance Method Divide time series length N into
blocks of size m Calc mean of each section Xm(k)
k= 1 … N/m Calc variance VXm of these Xm(k) Vary m size of the blocks
Plot on log-log & fit slope β Hurst parameter H
β = 2H -2 Measure:
β = -0.355 which gives H 0.822 H =1 no long range dependence
VLBI Project: Packet Loss – Long Range Effects?
y = -0.355x + 2.8826
0
0.5
1
1.5
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0 0.5 1 1.5 2 2.5 3sub-sample size Log10( m )
Ag
gri
ga
te-v
ari
an
ce L
og
10
( X
(m)
)
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Traffic Flows Manchester – NetNorthWest - SuperJANET Access links
Two 1 Gbit/s
Access links:SJ4 to GÉANT GÉANT to SurfNet
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
High Performance TCP – DataTAG Different TCP stacks tested on the DataTAG Network 128 ms round trip time Drop 1 in 106
High-SpeedRapid recovery
ScalableVery fast recovery
StandardRecovery would
take ~ 10 mins
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Drop 1 in 25,000 Rtt 6.2 ms Recover in 1.6 s
High Performance TCP – MB-NG
Standard HighSpeed Scalable
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Some Network Tests TCP Request – Response
Zero stats OK done
Send statistics:CPU load & no. int1-way delay
Send event data
Request-Response time (Histogram)
Request event
Get remote statistics
●●● ●●●
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Lab Test: TCP Request-Response Histograms PC – router – PC BE Test flow Request spacing 0 µs
Request spacing 10 ms
0.5M bytes man02-3_7may04
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4280 4300 4320 4340 4360 4380 4400 4420 4440 4460
Latency us
N(t
)
0.5M bytes w 10ms man02-3_7may04
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800
4280 4300 4320 4340 4360 4380 4400 4420 4440 4460Latency us
N(t
)
1.0M bytes man02-3_7may04
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8580 8600 8620 8640 8660 8680 8700 8720 8740 8760
Latency us
N(t
)
2.0 M bytes man02-3_7may04
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17080 17100 17120 17140 17160 17180 17200 17220 17240 17260
Latency us
N(t
)
1.0 M bytes w 10ms man02-3_7may04
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8580 8600 8620 8640 8660 8680 8700 8720 8740 8760
Latency us
N(t
)2.0 M bytes w 10ms man02-3_7may04
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17080 17100 17120 17140 17160 17180 17200 17220 17240 17260
Latency us
N(t
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Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Man-CERN: TCP Request-Response Latency DataTAG PC – backup link
BE Tests Request spacing 0 µs Win size 2.5Mbytes
Compare with UDP latency Large differences
Rtt of 20 msdelay*bw = 2.5 Mbytes
1Mbyte data = 690 pkts interesting bursts !
w05gva-gnt5_7May04_TCP
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Lat
ency
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req-resp UDP latency us
ave time
w05gva-gnt5_7May04_TCP
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min time
max time
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Man-CERN: UDP Throughput & Packet Loss DataTAG PC – backup link BE Tests Throughput
Packet loss
w05gva-gnt5_7May04_UDP
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its/
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50 bytes 100 bytes 200 bytes 400 bytes 600 bytes 800 bytes 1000 bytes 1200 bytes 1400 bytes 1472 bytes
w05gva-gnt5_7May04_UDP
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50 bytes 100 bytes 200 bytes 400 bytes 600 bytes 800 bytes 1000 bytes 1200 bytes 1400 bytes 1472 bytes
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Traffic Flows Manchester – NetNorthWest - SuperJANET Access links
Link to PC in M/c Access links: 1 GE Man to NNW
Total Man to NNW
NNW to SuperJANET4
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Divide time series of packets into 1000 slices of 50 packets
Total lost packets 1410 Average number / slice = 1.4
Calc Poisson Probability P(n, µ) = µ n e -µ
n!
Curves close but not exact Could be more than 1 process
VLBI Project: Packet Loss – Is it Poisson?
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0 5 10 15n num lost in sub-sample
N(n
)
run12b
1
1.3
1.4
1.8
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Traffic QoS Classes on GÉANT Backbone
Normal Traffic
Normal Traffic +
Less Than Best Effort 2.0 Gbit/s
Normal Traffic +
Radio Astronomy Data 500 Mbit/s
Normal Traffic +
Radio Astronomy Data +
Less Than Best Effort 2.0 Gbit/s
Max Throughput on 2.5 G PoS
Meeting on ATLAS Remote Farms. Copenhagen 11 May 2004R. Hughes-Jones Manchester
Some Measurements made during ER2002
No LBE
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0 20 40 60 80 100 120 140 160 180 200Transfer number
No.
Out
of
ord
er
0
5000
10000
15000
20000
25000
No
. L
ost
num_badorder
num_lost
With 1.8Gbit LBE
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
0 20 40 60 80 100 120 140 160Transfer number
No.
Out
of
ord
er
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15000
20000
25000
No
. L
ost
num_badorder
num_lost