1 / 37

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

yered
Télécharger la présentation

A Bandwidth Estimation Method for IP Version 6 Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  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

More Related