CPSC 641:
Project Brainstorming Session
Carey Williamson
Department of Computer Science
University of Calgary
1
PROJECT OVERVIEW
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A “typical” course project might involve:
– design/build/obtain appropriate testbed,
environment, or platform for your project
– extend/customize as needed
– obtain relevant data/measurements needed
– design suitable experiment: clear goal,
identify factors, levels, performance metrics
– obtain and present (new/interesting) results
2
Some Data Sets and Traces
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Web server access logs (1996)
Web proxy access logs (1998)
MPEG video traces (20 x 40,000 frames)
ISP measurements (4 traces, 1-2 minutes)
FrameRelay/ATM traces (5 traces)
Bellcore Ethernet LAN trace (1989)
TCP/IP packet traces (LBL, 24 hours, 1.8M)
See also the “Internet Traffic Archive”
3
Some Available Simulators
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ATM-TN simulator (ATM cell-level)
Clustered Web server simulator (cws)
Web proxy caching hierarchies (Muda)
Distributed Web proxy simulator (dws)
IP-TN simulator (U of C)
IP-TNE network emulator (U of C)
LBL’s ns-2 simulator (TCP packet level)
4
Some Useful Tools
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Synthetic Web proxy workload generation
Web client traffic model (mosaic, 1995)
LRD traffic analysis (R/S, V-T, AC, etc)
GUI for traffic modeling/analysis (synTraff)
Wavelet-based traffic model (Ram)
Synthetic MPEG video trace generation
Wireless Sniffer (network analyzer)
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Issues and Ideas
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Improving/extending WebTraff tool
Web client traffic modeling
Web proxy caching hierarchies
Hierarchical vs distributed caching
Web response time modeling
Improving network TCP flow model (dws)
Wavelet-based traffic forecasting
Wavelength assignment in WDM networks
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1. ATM-TN System Overview (1998)
Input
Data
Set
ATM-T
ATM-N
TMF
SimKit
Output
Data
Set
workstation
Report
Generation
Scripts
Report
ATM
MF
WarpKit
ESS
SMTW
UNIX
Hardware
SPARC, KSR, SGI
CBR Poisson Ethernet JPEG/MPEG Web TCP/IP/AAL5 ABR
Traffic Models
Switch and Network Models
ATM
MF
TMF
SimKit
WarpKit
SMTW
X
WaiKit
ESS
UNIX Operating System
Sequential: UNIX Workstations (SGI, SPARC, DEC, HP)
Parallel: SGI Power Challenge, SPARC 1000
2. Clustered Web Server Model
1
2
File
Server
3
Cache
Manager
Dispatcher
(Front End)
N
Web
Clients
Server
Nodes
9
Object
Store
Server Parameters
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Num server nodes
Mem cache size
Disk cache size
Cache replacement
policy for each (LRU,
LFU, SIZE, DUAL)
Comm. latency
Cache consistency
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Dispatch policy (DNS,
RR, Redirect, Load)
Request distribution
policy (requests, bw,
conns, affinity, ...)
Server bandwidth
Per-request bandwidth
BW scaling model
Performance Metrics
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Load balancing
–
–
–
–
–
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Cache performance
– document hit rate
– byte hit rate
requests
bytes
bandwidth
connections
clients
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Relative improvement
versus RR, Rand, etc
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Comm. overhead
Avg response time
Avg inflation factor
Others...
3. Web Proxy Caching Model
Web
Servers
Aggregate
Workload
Proxy
server
Web Clients
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Hierarchical Proxy Caching Simulation Model
Web
Servers
Complete
Overlap
Partial Overlap
(50%)
Proxy
server
Proxy
server
Upper Level
(Parent)
Proxy
server
Lower Level
(Children)
No Overlap
Web Clients
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Factors and Levels
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Cache size
Cache Replacement Policy
– Recency-based LRU
– Frequency-based LFU-Aging
– Size-based GD-Size
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Workload Characteristics
– One-timers, Zipf slope, tail index, correlation,
temporal locality model
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WebTraff Conceptual View
LLCD
F
Zipf
P
Correlation
-1 0 +1
s
r
ProWGen Software
Input
Parameters
1
Z
a
15
c
L
Synthetic
Workload
Key Workload Characteristics
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“One-timers” (60-70% useless!!!)
Zipf-like document referencing popularity
Heavy-tailed file size distribution (i.e., most
files small, but most bytes are in big files)
Correlations (if any) between document size
and document popularity (debate!)
Temporal locality (temporal correlation
between recent past and near future references)
[Mahanti et al. 2000]
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