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A Bandwidth Estimation Method for IP Version 6 Networks. Marshall Crocker Department of Electrical and Computer Engineering Mississippi State University October 13, 2006. Outline. Introduction to Bandwidth and Estimation Motivation IPv4 Estimation Techniques - PowerPoint PPT Presentation
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A Bandwidth Estimation Method for IP Version 6 Networks
Marshall Crocker
Department of Electrical and Computer Engineering
Mississippi State University
October 13, 2006
Page 2 of 37MS Thesis Presentation
Outline
• Introduction to Bandwidth and Estimation
• Motivation
• IPv4 Estimation Techniques
• IPv6 Overview and Estimation Technique
• Simulation Experimentation
• Conclusions and Future Work
Page 3 of 37MS Thesis Presentation
What is Bandwidth?
• Important characteristic of data networks How much data How fast
• Determined by two primary properties Physical Link Capacity Infrastructure Utilization
Data?
100 Mb/s10 Mb/s
% Load
Page 4 of 37MS Thesis Presentation
What is Bandwidth Estimation?
• Nodes attempt to estimate network bandwidth Determine minimum physical capacity called Bottleneck Bandwidth Determine unused capacity called Available Bandwidth
• Estimations are used in many different ways
• Many different techniques for performing estimations
100 Mb/s10 Mb/s
90% Load
Page 5 of 37MS Thesis Presentation
Sending rate less than
BWE?
Applications of BWE
• End-to-end flow control
Increase Rate
Decrease Rate
yes
no
Page 6 of 37MS Thesis Presentation
Applications of BWE
• Server selection for downloads and streaming media
• Peer-to-peer selection Connect to peers with most bandwidth
• Traffic Engineering Adjust routing/switching for optimal operation
• Capacity Provisioning Increase/decrease capacity as needed
10
5
8
Page 7 of 37MS Thesis Presentation
Motivation
• BWE valuable for a number of applications
• IPv4 techniques Suffer from various flaws Limited due to nature of the network No single technique suitable for all applications Evolving network technologies affect theories
• IPv6 offers framework for improved estimation technique Efficient Flexible Accurate Simple
Page 8 of 37MS Thesis Presentation
IPv4 Estimation Techniques
• All measurements are passive
• Examine how network delivers data Packet spacing Packet delay Packet dispersion Statistical
Page 9 of 37MS Thesis Presentation
IPv4 Estimation Techniques
• Each suffer from one or more High level of complexity Poor efficiency Limited accuracy Application specificity
• Each method is susceptible to one or more Network load Cross-traffic Packet-size variability Probing packet size Train length Cross-traffic routing
Page 10 of 37MS Thesis Presentation
Incorrect IPv4 Bandwidth Estimation Scenario
Page 11 of 37MS Thesis Presentation
IP Version 6
• Next generation Internet Protocol
• Improves on IPv4 Expanded addressing from 32 bits to 128 Simplified header Improved extension and option support
• Extension support provides framework for improved bwe technique
Page 12 of 37MS Thesis Presentation
Data
….
IPv6 Header
Ver 6 Traffic Class Flow Label
32 bits
Payload Length Next Hdr. Hop Limit
Source Address
Destination Address
Extensions
Page 13 of 37MS Thesis Presentation
IPv6 Extensions
• Several different extensions Routing Fragmentation Destination options Authentication Security Hop-by-hop
• Examined by every hop • Provides instructions for each hop• Only two options currently defined
Jumbo payload Router alert
Page 14 of 37MS Thesis Presentation
Proposed Hop-by-Hop Options
• Traceroute Each hop inserts address Record forward/backward path Not accepted by IETF
• Connection Status Investigation (CSI) Request statistics/attributes for each hop IP address Bandwidth Type Number of transmitted/received bytes/packets Number of errors
Page 15 of 37MS Thesis Presentation
IPv6 Timestamp Option
• CSI would have been extremely useful
• Rejected by IETF due to complexity, security, and proprietary concerns
• A timestamp option was defined for IPv4 but had limited use
• An IPv6 timestamp option has much more potential including bandwidth estimation
Page 16 of 37MS Thesis Presentation
IPv4 Timestamp Deficiencies
• IPv4 timestamp option limited in usefulness
Can only hold timestamps for up to 9 hops without addresses
Room to hold 4 hops with addresses
No standard for defining timestamp format
IPv4 routers services packets with options slower
Page 17 of 37MS Thesis Presentation
IPv6 Timestamp
• IPv6 timestamp properties
Enough room to hold timestamp records for every hop
Predefined timestamp format
Timestamp at incoming and/or outgoing interfaces
Page 18 of 37MS Thesis Presentation
IPv6 Timestamp Format
Next Hdr. Hdr. Ext Len Option Type Option Data Len
32 bits
Record Count TS Type Hop Limit BaseRes IfOptR
Identifier Reserved
Upper Part of IPv6 Address
Lower Part of IPv6 Address
Hop Number CounterLk TypeI/FResolutionG
TimestampFmt
Page 19 of 37MS Thesis Presentation
IPv6 Timestamp BWE
• Define bandwidth as number of transmitted bits per unit time
• Expand to include start and end transmit times
• Use start/end transmit times of packet and packet size to calculate capacity
• Send two timestamp packets back-to-back
• Timestamp of first packet and timestamp of second packet = t1 and t2
• Size of first packet and link layer size used in final calculation
t
bC
12 tt
bC
Page 20 of 37MS Thesis Presentation
Bottleneck Bandwidth Estimation
LeadTail
Router
TS = 10TS = 15
1015
SizeLeadPacketC
Page 21 of 37MS Thesis Presentation
Bottleneck Bandwidth Estimation
• Relies on back-to-back queuing
• Count field in TS record ensures back-to-back
• Smaller tail packet helps back-to-back queuing
Page 22 of 37MS Thesis Presentation
1020
SizeLeadPacketC
Available Bandwidth Estimation
LeadTail
Router
TS = 10TS = 20
CT
Page 23 of 37MS Thesis Presentation
Available Bandwidth Estimation
• Relies on cross traffic to introduce packet separation
• Constantly changing value
• Applications must send estimations frequently
Page 24 of 37MS Thesis Presentation
Simulation Experimentation
• Simulation experiments used to compare and evaluate IPv6 Timestamp method
• Measured against comparable IPv4 method called the cartouche method
• Cartouche method uses packet trains and examines packet spacing to estimate BW
Page 25 of 37MS Thesis Presentation
Simulation Setup
Page 26 of 37MS Thesis Presentation
Simulation Setup
Parameter Values
Number of Cross Traffic Flows 8, 16, 24, 32, 40, 48
Cross Traffic Rates 100 Kbps, 1 Mbps
Average Cross Traffic Size 200 Bytes
Leading Probe Packet Size 1500 Bytes
Bottleneck Rates (Mbps) 10, 20, 30, 40, 50,60, 70, 80, 90, 100
Hop Rates 100 Mbps
Page 27 of 37MS Thesis Presentation
Estimation Method Parameters
Scenario CT Rate Tailgating Packet Size (Bytes)
1 100 Kbps 212
2 100 Kbps 76
3 1 Mbps 212
4 1 Mbps 76
Scenario CT Rate Tailgating Packet Size (Bytes)
Cartouche Length (r)
1 100 Kbps 40 2
2 100 Kbps 40 3
3 1 Mbps 40 2
4 1 Mbps 40 3
Page 28 of 37MS Thesis Presentation
IPv6 Estimation Results
Scenario 1 Scenario 4
Page 29 of 37MS Thesis Presentation
Cartouche Estimation Results
Scenario 1 Scenario 4
Page 30 of 37MS Thesis Presentation
IPv6 Estimation Frequency
IPv6 Bandwidth Measurements 100 Kbps Cross Traffic Flows
0
100
200
300
400
500
600
700
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
ency
Page 31 of 37MS Thesis Presentation
IPv6 Estimation Frequency
IPv6 Bandiwdth Measurements 1 Mbps Cross Traffic Flows
0
100
200
300
400
500
600
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
en
cy
Page 32 of 37MS Thesis Presentation
Cartouche Estimation Frequency
Cartouche Bandwidth Measurements 100 Kbps Cross Traffic Flows
0
50
100
150
200
250
300
350
400
450
500
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
en
cy
Page 33 of 37MS Thesis Presentation
Cartouche Estimation Frequency
Cartouche Bandwidth Measurements for 1 Mbps Cross Traffic Flows
0
20
40
60
80
100
120
140
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
enc
y
Page 34 of 37MS Thesis Presentation
Cartouche Estimation Frequency
Cartouche Bandwidth Measurements 100 Kbps Cross Traffic Flows Bottleneck = 90 Mbps
0
10
20
30
40
50
60
70
80
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
en
cy
Page 35 of 37MS Thesis Presentation
Cartouche Estimation Frequency
Cartouche Bandwidth Measurements for 1 Mbps Cross Traffic FlowsBottleneck = 90 Mbps
0
2
4
6
8
10
12
14
16
18
0 10 20 30 40 50 60 70 80 90 100
Measured Bandwidth (Mbps)
Fre
qu
en
cy
Page 36 of 37MS Thesis Presentation
Conclusions
• Presented IPv6 bandwidth estimation using timestamp hop-by-hop option
• Advantageous over existing methods Efficient Simple Flexible Accurate
• IPv4 bandwidth estimations are limited due to the nature of the network
• Outperforms comparable IPv4 Technique
Page 37 of 37MS Thesis Presentation
Future Work
• Extended simulation models Diverse network properties and conditions Additional hardware and communications models Additional host and network models
• Real world implementation
• Development of network control techniques, protocols and applications such as a “Cognizant” version of TCP Aware of network Intelligently respond to network and conditions Fairly use network resources