ISP and Egress Path Selection for Multihomed Networks Amogh Dhamdhere, Constantine Dovrolis
Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang...
-
Upload
lillian-obrien -
Category
Documents
-
view
212 -
download
0
Transcript of Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang...
![Page 1: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/1.jpg)
Internet Measurement Conference 2003
Source-Level IP Packet Bursts: Causes and Effects
Hao Jiang Constantinos Dovrolis
(hjiang, [email protected])
College of ComputingGeorgia Institute of Technology
![Page 2: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/2.jpg)
Main questions
Source-level burst: several IP packets sent back-to-back from the source of an individual flow Strongly correlated packet interarrivals within a flow
Which are the causes of source-level bursts? Identify several protocol/application causes
Can source-level bursts create scaling in short timescales? Yes, in timescales that correspond to duration of bursts
What is the impact of source-level bursts on queueing performance? Increased maximum backlog and queue-size tail
distribution
![Page 3: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/3.jpg)
Causes of source-level bursts
UDP message segmentation Unused congestion window increases Packet reordering Idle restart timer bug Bursty applications Cumulative or lost ACKs Slow start Loss recovery with Fast Retransmit ACK compression
![Page 4: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/4.jpg)
UDP message segmentation in multiple IP packets/fragments
![Page 5: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/5.jpg)
• Normally, if sender stays idle for more than certain timer, TCP should restart in slow start
• Otherwise, entire window can be sent back-to-back
![Page 6: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/6.jpg)
Multi-Resolution Analysis of traffic process
Time series of traffic process at scale Tj=2jT0 :
Amount of traffic in
Energy at scale Tj:
Compute energy plots using wavelet-based MRA tool (Darryl Veitch)
,...1,0},,{ jZkX jkjX
])1(,[ jjjk TkkTt
)](2[
][112
12
2/
jk
jk
j
jkj
XXVar
dVarΕVariance of Haar wavelet coefficients at scale Tj
![Page 7: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/7.jpg)
Scaling behavior and energy plots
Short-time scaling vs long-time scaling Short-time scaling corresponds to sub-RTT timescales
![Page 8: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/8.jpg)
Packet-train model of source-level bursts
Parameters: L, C, N, Toff
Correlated packet interarrivals within burst All bursts have same characteristics Ignore all other correlations
![Page 9: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/9.jpg)
Source-level bursts cause short-time scaling
Energy plot Scaling from L/C to
NL/Cwith slope 2.0
Autocorrelation function Linearly decreasing
correlations up to NL/C
![Page 10: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/10.jpg)
Burst detection in packet traces
Detect burst as sequence of packets from a single flow that arrives at trace point with burst rate ≈ pre-trace capacity
NOTE: we may detect more than source-level bursts
How to estimate pre-trace capacity? Estimate minimum-capacity on the path
between source host and trace-point Use packet pair dispersion technique
Apply only to equal-sized packets
TCP sends many packet pairs due to delayed-ACK algorithm
![Page 11: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/11.jpg)
Example of pre-trace capacity distribution
Observe modes at 1.5Mbps, 10Mbps, 45Mbps, and 100Mbps
![Page 12: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/12.jpg)
What if there were no bursts?
Modify trace by “spreading” detected burst: Uniform respacing of packets within burst Not possible in practice
![Page 13: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/13.jpg)
Effect of bursts on short-time scaling
Decreases scaling exponent to almost zero in sub-RTT timescales
![Page 14: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/14.jpg)
But not entirely..
![Page 15: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/15.jpg)
Effect of bursts on queueing performance
Significant reduction of maximum backlog in moderate utilization (infinite-buffer model)
![Page 16: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/16.jpg)
Effect of bursts on queueing performance
Faster decrease of queue-size tail probability
![Page 17: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/17.jpg)
Conclusions
Various protocol/applications mechanisms create source-level bursts
Source-level bursts can cause short-time scaling in Internet traffic But they are not the only reason
Removal of bursts would decrease scaling in sub-RTT timescales and would improve queueing performance
More recent work: Effect of self-clocking on short-time scaling Effect of TCP pacing and TB-shaping on short-time scaling
![Page 18: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/18.jpg)
Unused congestion window increase
![Page 19: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/19.jpg)
ACK reordering
![Page 20: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/20.jpg)
Cumulative or lossed ACKs
![Page 21: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/21.jpg)
Loss recovery with fast retransmission
![Page 22: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/22.jpg)
ACK compression
![Page 23: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/23.jpg)
Bursty application
![Page 24: Internet Measurement Conference 2003 Source-Level IP Packet Bursts: Causes and Effects Hao Jiang Constantinos Dovrolis (hjiang, dovrolis@cc.gatech.edu)](https://reader036.fdocuments.us/reader036/viewer/2022070305/55150658550346a80c8b5653/html5/thumbnails/24.jpg)
• Slow start can cause bursts when W < CT
C: capacity of source & path, T: Round-Trip Time