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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

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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
Outline

  • Introduction to Bandwidth and Estimation

  • Motivation

  • IPv4 Estimation Techniques

  • IPv6 Overview and Estimation Technique

  • Simulation Experimentation

  • Conclusions and Future Work


What is bandwidth
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?


What is bandwidth estimation
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


Applications of bwe
Applications of BWE

  • End-to-end flow control

Decrease Rate

no

yes

Sending rate less than BWE?

Increase Rate


Applications of bwe1
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


Motivation
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


Ipv4 estimation techniques
IPv4 Estimation Techniques

  • All measurements are passive

  • Examine how network delivers data

    • Packet spacing

    • Packet delay

    • Packet dispersion

    • Statistical


Ipv4 estimation techniques1
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



Ip version 6
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


Ipv6 header
IPv6 Header

32 bits

Ver 6

Traffic Class

Flow Label

Payload Length

Next Hdr.

Hop Limit

Source Address

Destination Address

Extensions

….

Data


Ipv6 extensions
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


Proposed hop by hop options
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


Ipv6 timestamp option
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


Ipv4 timestamp deficiencies
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


Ipv6 timestamp
IPv6 Timestamp

  • IPv6 timestamp properties

    • Enough room to hold timestamp records for every hop

    • Predefined timestamp format

    • Timestamp at incoming and/or outgoing interfaces


Ipv6 timestamp format
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


Ipv6 timestamp bwe
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


Bottleneck bandwidth estimation
Bottleneck Bandwidth Estimation

Router

TS = 15

TS = 10

Tail

Lead


Bottleneck bandwidth estimation1
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


Available bandwidth estimation
Available Bandwidth Estimation

Router

TS = 20

TS = 10

Tail

CT

Lead


Available bandwidth estimation1
Available Bandwidth Estimation

  • Relies on cross traffic to introduce packet separation

  • Constantly changing value

  • Applications must send estimations frequently


Simulation experimentation
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





Ipv6 estimation results
IPv6 Estimation Results

Scenario 1 Scenario 4


Cartouche estimation results
Cartouche Estimation Results

Scenario 1 Scenario 4








Conclusions
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


Future work
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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