Squandering Resources

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C O M P U T A T I O
N A L R E S E A R
C H D I V I S I O N
Squandering Resources Jason R. Lee
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Overview

• Simulation
• Emulation
• Emulab
• Planetlab
• Putting it all together

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Simulation

• Popular simulator is NS
• Can simulate new protocols at a high level
• Controlled through tcl script
• Very computational expensive
• Cant accurately represent everything
• Hardware interrupts, random sun spots

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Example ns script
Create a simulator object set ns new
Simulator Open the nam trace file set nf open
out.nam w ns namtrace-all nf Define a
'finish' procedure proc finish
global ns nf ns flush-trace Close the
trace file close nf Execute nam on the
trace file exec nam out.nam
exit 0
Create two nodes set n0 ns node set n1 ns
node Create a duplex link between the
nodes ns duplex-link n0 n1 1Mb 10ms
DropTail Call the finish procedure after 5
seconds of simulation time ns at 5.0
"finish" Run the simulation ns run
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Emulation

• Create an enviroment out of hardware that is
  emulating the actual topology of the network.
• Removes some of the abstraction found in
  simulation.
• Use real routers
• Use real Operating Systems
• Use real networks
• Cant Emulate every enviroment -(

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Emulab

• University Of Utah Emulab
• 178 PCs
• 8 IXPs
• 40 wide-area nodes
• 9 802.11 wireless nodes ( 21 soon)
• frontend to PlanetLab.

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Emulab (cont.)

• Allows for the dynamic creation of network
  topologies.
• Allows varied network configurations
• RED, Drop tail, etc.
• Varied latencies (1-200 ms)
• Bandwidth caps (1mbs - 100mbs)
• Large number of Nodes (100)

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Emulab (cont.)

• Uses same tcl script as NS!
• With some enhancements
• Can specify end node os
• Can specify routing parameters
• Can specify tar/rpm/etc to be loaded
• Can login (as root) and run anything
• Can create custom OS images

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Example Emulab script
set ns new Simulator source
tb_compat.tcl set nodeA ns
node set nodeB ns node set nodeC ns
node set nodeD ns node Create a droptail
link with a 50ms delay and a 30mbs bw limt set
link0 ns duplex-link nodeB nodeA 30Mb 50ms
DropTail set link loss to 0.01
tb-set-link-loss link0 0.01 set lan0 ns
make-lan "nodeD nodeC nodeB " 100Mb
0ms tb-set-node-os nodeA FBSD-STD set
node to FreeBSD tb-set-node-os nodeC RHL-STD
set node to RedHat ns rtproto Static ns
run
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Emulab Picts
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PlanetLab

• 412 nodes
• 143 sites
• All over the world

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PlanetLab (cont.)

• Act as a wide area overlay network
• Provide a test-bed for the creation of a set of
  building blocks for to test out new services.
• Think dns, monitoring, routing, p2p
• What services will the future internet need? And
  how to prototype them in todays enviroment?

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PlanetLab (cont)

• Clunky interface
• Have to be a PI to do anything
• Manually create slivers
• Manually pick nodes
• Manually login and setup nodes
• Manually install software

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Best of Both Worlds

• Emulab interface to planetlab.
• Pros
• NS script setup
• Fully automated installs (rpms/tarballs)
• Allows for easy creation/termination
• Cons
• Cant use custom kernels/images
• Its a real network.
• Machines/network is shared

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Emulab PlanetLab
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Emulab PlanetLab
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Emulab PlanetLab
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Gotachas

• rsa ssh keys seem to work best
• Some planetlab sites cant be reached from others
  (Internet 2 particularly)
• Install ssh-mime.pl (ability to click on webpage
  to login)

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Refs

• Emulab http//www.emulab.net/
• PlanetLab http//www.planet-lab.org/
• NS http//www.isi.edu/nsnam/ns/