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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

  • 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


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



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




  • 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




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


TS Type



Hop Limit Base



Upper Part of IPv6 Address

Lower Part of IPv6 Address






Lk Type

Hop Number


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


TS = 15

TS = 10



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


TS = 20

TS = 10




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

  • 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