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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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