Network Available Bandwidth Measurements

XiaoLong HE

Outline of the Talk

 Problems  Related Work  Traffic Design  Our Approach (SimProbe)  Analysis of Simulation Results  SMRT Implementation  Lessons Learned  Future Work 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 2

Why measurement?

 Measurement is critical to network control.

 Measurement for selecting server/ISP  Measurement for verifying network configuration  Measurement for designing real-time applications  Measurement for load balancing in WAN  Measurement for accounting 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 3

Taxonomy of Internet Network Measurement Approaches

 Sender-based vs. Receiver-based  Passive Watch vs. Active Probe  Layer of Protocol used 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 4

Measurement Problems



Route Fluttering



Packet Loss



Out of Order packet delivery



Clocks Synchronization



Routers reject ICMP due to denial of series attacks.

4/25/2020 XiaoLong He Network Available Bandwidth Measurements 5

Bottleneck Bandwidth

 Bottleneck bandwidth: the maximal rate at which data can be sent along a connection, determined by the slowest element in the entire chain. 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 6

Available Bandwidth

 Available Bandwidth:how fast can the data in fact be transmitted over the connection.

 [PacketSize/(PacketSize+CompetitorPacketSize)] * Bottleneck Bandwidth 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 7

Related Works



Bprobe/Cprobe -

Robert L. Carter and Mark E. Crovella, Boston University, 1996 

Ping -

M. Muuss, U.S.Army Ballistic Research Laboratory, 1983 

Traceroute -

Van Jacobson, Berkeley, Univeristy of California, 1997 

Treno -

M. Mathis and J. Mahdavi, Proceedings of INET’96, Montreal, 1996 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 8

Bprobe/Cprobe

  Bottleneck Bandwidth = (PacketSize/Time) Available Bandwidth = (S2+…+Sn)/(Tn-T1) 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 9

SimProbe Simulator

 To carry the thesis out, we build a Java-based discrete event simulator.

 Swing, Java2D and AWT packets for GUI design  Thread for comparing different probing methods  Port it to Unix (without GUI) for long time simulation 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 10

How traffic is generated in SimProbe Simulator

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Traffic Patterns supported by SimProbe



Flat/Static



Slope



Web (

modifed code by Arthur Blais

)

– Time between requests: Pareto Distribution – Number of embedded references: Pareto Distribution – Time between references: Weibull Distribution – File Size: Body (Lognormal Distribution) Tail (Pareto Distribution) 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 12

Network Topology Used in This Simulation Study

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Our Approaches

   Sending as few packets as possible. Using round trip time measurements for network available bandwidth.

Trip Time Measurement Formula: TripTime*MeasuredAvailableBandwidth = MinimalTripTime*MaximalAvailableBandwidth – Round Trip Time Measurement  SMRT  MMRT – Unidirectional Trip Time Measurement  SMUT  MMUT Time Gap between packets – ACB (Adaptive Cprobe) 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 14

SMRT(Single Msg Round Trip Time Measurement)

 Using multiple packets to find minimum of the round trip time of a connection  Using Bprobe to get the maximal available bandwidth of a connection  Sending single probing packet  Using round trip time to estimate the available bandwidth of the connection 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 15

MMRT

 Use Bprobe to get the maximal available bandwidth of a connection  Using multiple packets to find minimum of the round trip time of a connection  Sending multiple packets  Round trip time for estimating ABW 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 16

SMUT

 Use Bprobe to get the maximal available bandwidth of a connection  Using multiple packets to find minimum of the unidirectional trip time of a connection  Sending single probing packet  Using unidirectional trip time for estimating available bandwidth 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 17

MMUT

 Use Bprobe to get the maximal available bandwidth of a connection  Using multiple packets to find minimum of the unidirectional trip time of a connection  Sending multiple probing packets  Using unidirectional trip time for estimating available bandwidth 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 18

Simulation result analysis



Difference Metric:

|AvailableBandwidth - MeasuredAvailableBandwidth| AvailableBandwidth – AvailableBandwidth = [PacketSize/(PacketSize+QueuingSize)]* Bottleneck Bandwidth – MeasuredAvailableBandwidth = (MinimalTripTime*MaximalAvailableBandwidth)/ TripTime  DelayTime: TripTime - MinimalTripTime 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 19

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SMRT Random Characteristics

  Problem: Dependent on the arrival time of probing packet on bottleneck link Three Scenarios: 1) no queuing time, yields bottleneck available bandwidth.

2) yields the lower bound of bottleneck available bandwidth 3) yields average bottleneck available bandwidth 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 22

Impact of Packet Size on SMRT

 DelayTime rises when probing packets size increases.

 Smaller packet size gets worse results  RoundTripTime = MinimalRoundTripTime + DelayTime  Examples: – T1 / ( T1 +  T) – T2 / ( T2 +  T)

PacketSize impact on Difference

3.5

3 2.5

2 1.5

1 0.5

0 20 46 80 400 800

PacketSize (Bytes)

1200 1500

PackeSize impact on DelayTime

0.12

0.1

0.08

0.06

0.04

0.02

0 20 46 80 400 800 1200 1500

Pack e tSize (Byte s )

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Impact of Link Length on SMRT

LinkLe ngth/Diffe re nce

 The result accuracy is worse with the length increasing  Delay Time dominates RoundTrip Time at shorter link length  Propagation time dominates RoundTrip Time at longer link length 7 6 5 4 3 2 1 0 100 1000 10000 100000

Link Le ngth (m e te rs )

1000000 24 4/25/2020 XiaoLong He Network Available Bandwidth Measurements

Impact of Router Speed on SMRT

 No apparent difference for 1GBps or 10GBps  Router Speed affects the time gap between packets  Slow router speed enlarges the time gap between packets  Router Speed must be faster than link speed 1.4

1.2

1 0.8

0.6

0.4

0.2

0

RouterSpeed impact on Difference

1 2 1GBps 10GBps 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 25

Impact of Bottleneck Link Bandwidth on SMRT

 SMRT results follow the available bandwidth trend  SMRT performance is similar to the performance trend by SMRT performance with 10MBps bottleneck link bandwidth

SMRT result w ith 200MBps Bottleneck Bandw idth

AvailableBandwidth 250000000 200000000 Meas uredABandwidt h 150000000 100000000 50000000 0 1 2 3 4 5 6 7 8 9

Tim e

10 11 12 13 14 15 16 17

SMRT Performance with 200MBps Bottleneck Bandwidth

40 35 30 25 20 15 10 5 0 20 00 00 00 0 20 00 00 00 0 20 00 00 00 0 20 00 00 00 0 44 70 35 9.6

15 57 99 4.4

89 82 52 .56

62 32 59 .7

Available Bandwidth (Bps)

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MMRT

  Try to alleviate the random characteristic of SMRT Small time gap between probing packets may experience big traffic difference in Slope traffic pattern  Obvious improvement on SMRT performance in web traffic 4/25/2020

MMRT Performance

5 4.5

4 3.5

3 2.5

2 1.5

1 0.5

0 10 00 00 00 10 00 00 00 10 00 00 00 10 00 00 00 10 00 00 00 10 00 00 00 63 85 54 2.

55 2 84 16 0.

14 7 80 38 9.

80 1 48 61 .1

56 5 42 71 .3

39 5 96 93 .0

29 4 42 15 .3

21 3 81 79 .4

16 7 68 01 .4

8

Available Bandwidth

0.45

0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

Difference Comparison of SMRT and MMRT

SMRT MMRT XiaoLong He Network Available Bandwidth Measurements 27

SMUT

 Measure the available bandwidth on unidirectional route.

 SMUT has the same random characteristics as SMRT.

12000000 10000000 8000000 6000000 4000000 2000000 0

SMUT

Available Bandw idth Measured Available Bandw idth

Tim es

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MMUT

 Try to alleviate the random characteristic of SMUT  Small time gap between probing packets may experience big traffic difference with slope traffic pattern  MMUT has Better performance than SMUT with web traffic pattern 0.4

0.35

0.3

0.25

0.2

0.15

0.1

0.05

0

Difference Comparison of SMUT and MMUT

SMUT MMUT 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 29

 Using the last measured available bandwidth  Send two packets once a time  Reprobing in Cprobe if time gap between packets is inside of a range  Not better than Cprobe

ACB

Adaptive Cprobe

A vailable Band MA vailable Band 9000000 8000000 7000000 6000000 5000000 4000000 3000000 2000000 1000000 0 1 2 3 4 5 6 7 8

Time s

9 10 11 12 13 14 9000000 8000000 7000000 6000000 5000000 4000000 3000000 2000000 1000000 0

Cprobe

Available Band MAvailable Band

Times

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Summary of Simulation Analysis

12000000 10000000 8000000

Summary of Simulation Analysis

Cprobe Available Band Cprobe Measured Available Bandwidth SMRT AvailabeBandwidth SMRT Measured Available Bandwidth SMUT Available Bandwidth SMUT Measured Available Bandwidth 6000000 4000000 2000000 0 1 3 5 7 9 11 13 15 17

Times

19 21 23 25 27 29 31 31 4/25/2020 XiaoLong He Network Available Bandwidth Measurements

Implementation of SMRT

       SMRT is implemented in C Maintain a host file, which specifies the list of sites to be probed Bprobe is used to measure the largest bottleneck available bandwidth Ping is used to measure the smallest round trip time of a connection Using Bprobe and Ping to collect the history information for each host in the file, at offpeak and over a long period Probed host must be contained in the host file Round trip time of the probing message is used to measure the instant available bandwidth 32 4/25/2020 XiaoLong He Network Available Bandwidth Measurements

Implementation results of SMRT

 We probed a list of mirror sites for popular software packages such as perl, linux and netscape 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 33

Implementation results of SMRT

 Orst is good choice for us to download software

DownLoadTimes (seconds)

700 600 500 400 300 200 100 0 Ti m es 21 :0 0 PM 22 :0 0 PM 23 :0 0 PM 12 :0 0 AM 1: 00 2: A 00 M :0 0 3: AM 00 :0 0 4: AM 00 :0 0 5: AM 00 :0 0 6: AM 00 :0 0 7: AM 00 :0 0 8: AM 00 :0 0 9: AM 00 :0 0 AM

Times

UncDownloadTime gatechDownloadTime buffaloDownloadTime orstDownloadTime 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 34

Implementation results of SMRT

 Orst gives us relative short round trip time

RoundTripTime (ms)

160 140 120 100 80 60 40 20 0 Ti m es 21 :0 0 PM 22 :0 0 PM 23 :0 0 PM 12 :0 0 AM 1: 00 A 2: M 00 :0 0 AM 3: 00 :0 0 AM 4: 00 :0 0 AM 5: 00 :0 0 AM 6: 00 :0 0 AM 7: 00 :0 0 AM 8: 00 :0 0 AM 9: 00 :0 0 AM

Times

UncPing gatechPing buffaloPing orstPing 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 35

Lessons Learned

 Impact of router speed on traffic generation – Problem: When router speed is lower than the bottleneck link speed, we can not get expected traffic?

– Solution: Make sure the router speed in our connection is greater than the bottleneck link speed, especially for the large bottleneck link bandwidth 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 36

Lessons Learned (Cont)

  Cprobe Limitations – Probing returned packets interfere with later probing packets – Queuing time is not the only results from connection competition Examined factors: – Router Speed – Hop Number – Message Size – Message Number 37 4/25/2020 XiaoLong He Network Available Bandwidth Measurements

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Lessons Learned (Cont)

 OOP design in Java – Problem: Chart can not be updated when we call the chart in a thread directly.

– Solution: Using SwingUtilities.invokeLater Class  Double data type precision problem – Problem: The round trip time with traffic pattern is even shorter than the time without any traffic – Reason: machine double type data has a precision problem in representing a value exactly – Solution: Because difference is small, so ignore it 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 40

Future Works

 How to measure available bandwidth of a host whose history information is not available.  How to find a better available bandwidth estimation formula to improve the accuracy of SMRT  Convert MMRT, SMUT and MMUT simulation code from Java to C  More traffic route to test the reliability of SMRT and other methods 4/25/2020 XiaoLong He Network Available Bandwidth Measurements 41