the Ninja box (and BART) [email protected] Centre for...
Transcript of the Ninja box (and BART) [email protected] Centre for...
Test and Measurement withthe Ninja box (and BART)
David Hayes
Centre for Advanced Internet Architectures (CAIA)Swinburne University of Technology
Outline
Introduction - Test and Measurement in CAIAWhat is the Ninja Box?4.5G2 DAG cards
Clock SynchronisationData Stream ManagementBasic CaptureBasic Traffic Generation
Simple ExperimentSetupResults
Port Mirroring DelaysConclusionsThanks
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 2
IntroductionTest and Measurement in CAIA
Test and Measurement of various network characteristics isa vital part of CAIA’s research.The Endace Ninja Box(http://www.endace.com/ninjabox.html) willenhance our traffic measurement and traffic generationcapabilities.This talk will outline the Ninja Box capabilities in conjunctionwith:
The Broadband Access Research Testbed (BART)http://caia.swin.edu.au/bart/The Synthetic Packet Pair (SPP) tool for passive Round TripTime (RTT) measurement.http://caia.swin.edu.au/tools/spp/
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 3
What is the Ninja Box?
Server grade machine, optimised for packet captureOur Configuration:
2× 2 GHz Intel(R) Xeon(R) core 2 duoLinux kernel 2.6.18, Centos OS, 4G ram2TB disk (8 disk raid)2×DAG 4.5G2 – Precision packet capture cards
http://www.endace.com/ninjabox.html
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 4
4.5G2 DAG cardsData Stream ManagementInline ForwardingTimed Release ERF
Endace, “Dag 4.5 G2 Card User Guide”, 2008, p3
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DAG Clock Synchronisation
Geographically separated measurementsSynchronise with GPS
We currently synchronise DAD 0 to the PC clock
Dag cards synchronised to each otherPC is synchronised by NTPDAG cards synchronised to PC by DUCK
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 6
DAG Clock Synchronisation
Geographically separated measurementsSynchronise with GPS
We currently synchronise DAD 0 to the PC clockDag cards synchronised to each otherPC is synchronised by NTPDAG cards synchronised to PC by DUCK
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 6
DAG Data Stream Management
Filter/load balancingPacket colourising and droppingPacket steering
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DAG Data Stream Management
Packets are received fromone or both portsEither:
Use inbuilt loadbalancing classifierOr Classify (and drop)based on programmablefilters
Colourise (based on aboveresult)Steer to stream buffer
2Rx and 1Tx per DAG)
Steering can includeduplication
Endace, “Enhanced Packet Processing
Software Guide”, 2008, p3
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Basic Capture
dagsnap — high speed capture (erf)packets from a previous capture session
Post process if necessary (WAND libtrace (http://research.wand.net.nz/software/libtrace.php)
traceanontracefiltertracesplittracemerge
dagconvert — change format (ie to pcap)
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Basic Traffic Generation
daggenConfiguration file to describe trafficAddresses can be randomPayloads can vary, deterministically or randomlyOutputs ERF format file (or can go direct to DAG)
dagfloodSends ERF fileTo flood link: dagconfig nodelayFor timed replay: dagconfig relative
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Simple Experiment
Objective
Familiarity with:NinjaBox (http://www.endace.com/ninjabox.html),BART (http://caia.swin.edu.au/bart/),and SPP (http://caia.swin.edu.au/tools/spp/)
Compare NinjaBox and PC based tcpdump(http://www.tcpdump.org/) captures
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 11
Setup
ADSL Modem
BART
SWIN
Mirrored ports
BA
Workgroup Switch
CatalystCiscoSystems
MeasureRTTA→←↩Bfor scpA→ B
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Results RTT A→←↩B
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
0 50 100 150 200 250
RTT
(s)
Time since first captured packet (s)
NinjaBoxTcpDump
ObservationsTCP sawtooth
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Results RTT A→←↩B — Zoom
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
151.5 152 152.5 153 153.5 154
RTT
(s)
Time since first captured packet (s)
NinjaBoxTcpDump
Observations100MbpsburstAck clockedRx TCP Ackswhile awaitingssh response
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Results RTT A→←↩B — Zoom
1
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
151.744 151.744 151.745 151.745 151.746 151.746 151.747 151.747 151.748 151.748 151.749
RTT
(s)
Time since first captured packet (s)
NinjaBoxTcpDump
ObservationsPcap timestamp – time kernel saw packet,Not time sent on the wireDag timestamp – mirrored
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Results RTT A→←↩B — Zoom
1.23
1.2305
1.231
1.2315
1.232
151.745 151.745 151.745 151.746 151.746 151.746 151.746 151.746 151.746 151.746 151.746
RTT
(s)
Time since first captured packet (s)
NinjaBoxTcpDump
ObservationsLocal tcpdump overestimatesRTT
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Port Mirroring Delays
UP direction
∆tup = τrx + τAin + τcopy + τMout
Perturbation depends on:
Packet sizeSwitch loadFull duplex utilisation
Switch
A
B
M
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Port Mirroring Delays
UP direction
∆tup = τrx + τAin + τcopy + τMout
DOWN direction
∆tdown = τcopy + (τMout − τAout)
Perturbation depends on:Packet sizeSwitch loadFull duplex utilisation
Switch
A
B
M
Caia Seminar http://www.caia.swin.edu.au [email protected] 12 March, 2009 17
Conclusions
Ninjabox will provide increased test and measurementcapabilities for CAIASPP is a great tool for RTT calculationWhen very accurate timing is required:
Care should be taken with the DAG clock synchronisationCare should be taken with how the packets are captured
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Thanks
JasonAmielLawrence
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