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A Bandwidth Estimation Method for IP Version 6 Networks

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

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A Bandwidth Estimation Method for IP Version 6 Networks

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  1. A Bandwidth Estimation Method for IP Version 6 Networks Marshall Crocker Department of Electrical and Computer Engineering Mississippi State University October 13, 2006

  2. Outline • Introduction to Bandwidth and Estimation • Motivation • IPv4 Estimation Techniques • IPv6 Overview and Estimation Technique • Simulation Experimentation • Conclusions and Future Work

  3. What is Bandwidth? • Important characteristic of data networks • How much data • How fast • Determined by two primary properties • Physical Link Capacity • Infrastructure Utilization % Load 100 Mb/s 10 Mb/s Data?

  4. 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/s 10 Mb/s 90% Load

  5. Applications of BWE • End-to-end flow control Decrease Rate no yes Sending rate less than BWE? Increase Rate

  6. 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

  7. 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

  8. IPv4 Estimation Techniques • All measurements are passive • Examine how network delivers data • Packet spacing • Packet delay • Packet dispersion • Statistical

  9. 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

  10. Incorrect IPv4 Bandwidth Estimation Scenario

  11. 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

  12. IPv6 Header 32 bits Ver 6 Traffic Class Flow Label Payload Length Next Hdr. Hop Limit Source Address Destination Address Extensions …. Data

  13. 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

  14. 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

  15. 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

  16. 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

  17. IPv6 Timestamp • IPv6 timestamp properties • Enough room to hold timestamp records for every hop • Predefined timestamp format • Timestamp at incoming and/or outgoing interfaces

  18. IPv6 Timestamp Format 32 bits Next Hdr. Hdr. Ext Len Option Type Option Data Len Record Count R TS Type Res IfOpt Hop Limit Base Identifier Reserved Upper Part of IPv6 Address Lower Part of IPv6 Address Fmt Timestamp G Resolution I/F Lk Type Hop Number Counter

  19. 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

  20. Bottleneck Bandwidth Estimation Router TS = 15 TS = 10 Tail Lead

  21. 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

  22. Available Bandwidth Estimation Router TS = 20 TS = 10 Tail CT Lead

  23. Available Bandwidth Estimation • Relies on cross traffic to introduce packet separation • Constantly changing value • Applications must send estimations frequently

  24. 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

  25. Simulation Setup

  26. Simulation Setup

  27. Estimation Method Parameters

  28. IPv6 Estimation Results Scenario 1 Scenario 4

  29. Cartouche Estimation Results Scenario 1 Scenario 4

  30. IPv6 Estimation Frequency

  31. IPv6 Estimation Frequency

  32. Cartouche Estimation Frequency

  33. Cartouche Estimation Frequency

  34. Cartouche Estimation Frequency

  35. Cartouche Estimation Frequency

  36. 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

  37. 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

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