ModelNet: Scalability and Accuracy in a Large-Scale Network Emulator
Ken Yocum, Kevin Walsh, Amin Vahdat, Priya Mahadevan, Dejan Kostic, Jeff Chase, and David Becker
Duke University, http://issg.cs.duke.edu
Goal: develop and explore scalability techniques for distributed service evaluation
ModelNet: Wide-area Emulation
•simulation– slow, must modify applications
•live deployment– limited in size, waiting for failures, not reproducible
•Emulation– static, small scale, hard to configure
•ModelNet: – accurate: error<1ms @ 95% cpu utilization– multiple techniques trade scalability for accuracy– Run unmodified applications on unmodified OS’s– reproducible results (recreate flash crowds, network partitions, etc)
– Supports overlays, wireless networking, content distribution networks, peer-to-peer systems . . .
faultscross traffic
1.) Create
bandwidthlatency
loss
4.) Bind
5.) Run
Map virtual to physical
trade accuracy for scalability
observe
target topology
ModelNet Performance
0
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0 20 40 60 80 100 120
1 hop2 hop3 hop4 hop
10Mbit flows
packets
/secon
d
FreeBSD 4.5, Architecture X Single Core Capacity (10vn’s/edgenode)
•Per-Hop cost = 2.8 µs•Per-packet cost = 8 µs•Distillation matters•packet sizes (1500 bytes), full mesh
ModelNet Validation Chord CFS
clients
3.) Assign
transits
stubs
topological cuts
core A
core B
core C
•Assign links to cores.
•balance load•reduce inter-core
traffic– replicate pipes– observe/adjust
•Graph partitioning problem– Spectral Analysis– Kernighan & Lin
ip
ipfwsrc:10.0.0.0/8 dst:10.0.0.0/8
app1 app2 app3 app4
Unmodified KernelLinux/FreeBSD/Solarisroute 10.1.0.0/16 -> core
interception DLLw.x.y.z -> 10.0.0.0/8
100 Mb/s
1 Gb/s
Network Switch
network interface
network interface
core ycore x
kernel
cross traffic emulation
modelnet emulated link
delay loss
emulated link...
routing matrix to
from
route lookup
client coreedge nodes emulation hardware
2.) Distilladaptive mesh refinement
preserve first hop
walk_in = 1
preserve corewalk_out = 1
clients
transits
stubs
Install ModelNetDataBase
configuration
balance load &minimize hardware footprint
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CFS 8-KB
MN 8-KB
CFS 64-KB
MN 64-KB
CFS 1126-KB
MN 1126-KB
cu
mu
lati
ve p
erc
en
tag
e o
f tr
an
sfe
rs
KB/second
•Emulated RON•reproduce end-to-end effects•uses single edge node
•multiple cores•payload caching•ship description of packet, not data
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