In VINI Veritas Realistic and Controlled Network Experimentation

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In VINI VeritasRealistic and Controlled Network
Experimentation

• Andy Bavier Nick Feamster Mark Huang
• Larry Peterson Jennifer Rexford

Princeton University Georgia Tech
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How to Validate an Idea?
Emulation
VINI
Simulation
Small-scale experiment
Live deployment

• Fixed, shared among many experiments
• Runs real routing software
• Exposes realistic network conditions
• Gives control over network events
• Carries traffic on behalf of real users

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Scientific Value
The most exciting phrase to hear in science, the
one that heralds new discoveries, is not
Eureka! (I found it!) but Thats funny --
Isaac Asimov

• Move off the emulator, into the wild
• Opportunity for more thats funny moments
• Avoid Fallacy of Misplaced Concreteness
• Simulation and emulation are important tools
• Modeling abstracts general properties from
  reality
• Philosophy the devil may be in the details
• But insights and soundness are found there too

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Controlled Realism

• Start with a controlled experiment
• Relax constraints, study effects
• Result an operational virtual network thats
• Feasible
• Valuable
• Robust
• Scalable, etc.

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Overview

• VINI requirements
• Fixed, shared infrastructure
• Flexible network topology
• Expose/inject network events
• External connectivity and routing adjacencies
• Strategy for building VINI
• PL-VINI prototype on PlanetLab
• Experimental results
• Timeline

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Fixed Infrastructure
Deploying VINI nodes in National LambdaRail,
Abilene with Gigabit links
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Shared Infrastructure
Experiments given illusion of dedicated h/w
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Flexible Topology
VINI supports arbitrary virtual topologies
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Network Events
VINI exposes, can inject network failures
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External Connectivity
s
Experiments can carry traffic for real end-users
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External Routing Adjacencies
s
Experiments can participate in Internet routing
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PlanetLab ? VINI

• Build VINI from PlanetLab, a global testbed for
  distributed services
• Begun in 2002
• 700 nodes at 336 sites in 35 countries
• 600 projects and 2500 researchers
• Serves 3-4 TB/day to 1M clients
• MyPLC PlanetLab software distribution
• Anyone can run their own private PlanetLab

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PlanetLab Experiments

• Simultaneous experiments in separate VMs
• Each has root in its own VM, can customize
• Reserve CPU, network capacity per experiment

Node Mgr
Local Admin
VM1
VM2
VMn

PlanetLab node
Virtual Machine Monitor (VMM) (Linux)
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PL-VINI Prototype on PlanetLab

• Feasible? ? prototype on public PlanetLab
• Enable experiment Internet In A Slice
• XORP open-source routing protocol suite (NSDI
  05)
• Click modular router (TOCS 00, SOSP 99)
• Clarify issues that a VINI must address
• Unmodified routing software on a virtual topology
• Forwarding packets at line speed
• Illusion of dedicated hardware
• Injection of faults and other events

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XORP Control Plane
XORP (routing protocols)

• Goal real routing protocols on virtual network
  topologies
• BGP, OSPF, RIP, PIM-SM, IGMP/MLD
• XORP can run in a PlanetLab VM

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User-Mode Linux Environment
UML
XORP (routing protocols)

• Interface network
• PlanetLab limitation
• Experiments cannot create new interfaces
• Run routing software in UML environment
• Create virtual network interfaces in UML

eth1
eth3
eth2
eth0
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Click Data Plane
UML
XORP (routing protocols)

• Performance
• Avoid UML overhead
• Move to kernel, FPGA
• Interfaces ? tunnels
• Click UDP tunnels correspond to UML network
  interfaces
• Filters
• Fail a link by blocking packets at tunnel

eth1
eth3
eth2
eth0
Control
Data

Packet Forward Engine
UmlSwitch element
Tunnel table
Click
Filters
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Resource Isolation

• Issue Forwarding packets in user space
• PlanetLab sees heavy use
• CPU load affects virtual network performance

Property Depends On Solution
Throughput CPU received PlanetLab provides CPU reservations
Latency CPU scheduling delay PL-VINI boost priority of packet forward process
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Intra-domain Route Changes
s
2095
856
700
260
233
1295
c
639
548
366
846
587
902
1893
1176
Watch OSPF route convergence on Abilene
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Ping During Link Failure
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TCP Throughput
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Arriving TCP Packets
PL-VINI enables a user-space virtual network to
behave like a real network on PlanetLab
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Attracting Real Users

• Could have run experiments on Emulab
• Goal Operate our own virtual network
• Carrying traffic for actual users
• We can tinker with routing protocols
• We expect that
• PlanetLab services will subscribe to VINI network
  architectures to access Gb/s
• Experiments will advertise routes via BGP

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Timeline
Other features?
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The End

• Questions?

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The End

• URL http//www.vini-veritas.net
• Questions?

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Backup slides
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Conclusion

• VINI evolution of PlanetLab
• Installing VINI nodes in NLR, Abilene
• Download and run Internet In A Slice
• MyPLC ? MyVINI as code diverges
• Build, run, modify your own VINI
• We expect there to be many VINIs

http//www.vini-veritas.net
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Timeline

• Conclude with a timeline instead? Like the one
  for Gibson.
• Experiments on the top, infrastructure on the
  bottom, You are here.
• Today IIAS, PL-VINI
• Next RCP, VINI-NLR
• What other experiments?

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Ongoing Work

• Improving realism
• Exposing network failures and changes in the
  underlying topology
• Participating in routing with neighboring
  networks
• Improving control
• Better isolation
• Experiment specification

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Performance is bad

• User-space Click 200Mb/s forwarding
• Can do a lot with 200Mb/s
• 20 experiments can have dedicated 10Mb/s
  nationwide networks
• Improving performance is ongoing work
• Allow experiments to load custom Click modules
  into the VINI kernel

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PL-VINI Summary
Flexible Network Topology Flexible Network Topology
Virtual point-to-point connectivity Tunnels in Click
Unique interfaces per experiment Virtual network devices in UML
Exposure of topology changes Upcalls of layer-3 alarms
Flexible Routing and Forwarding Flexible Routing and Forwarding
Per-node forwarding table Separate Click per virtual node
Per-node routing process Separate XORP per virtual node
Connectivity to External Hosts Connectivity to External Hosts
End-hosts can direct traffic through VINI Connect to OpenVPN server
Return traffic flows through VINI NAT in Click on egress node
Support for Simultaneous Experiments Support for Simultaneous Experiments
Isolation between experiments PlanetLab VMs and network isolation CPU reservations and priorities
Distinct external routing adjacencies BGP multiplexer for external sessions
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PL-VINI / IIAS Router
UML
XORP (routing protocols)

• XORP control plane
• UML environment
• Virtual interfaces
• Click data plane
• Performance
• Avoid UML overhead
• Move to kernel, FPGA
• Interfaces ? tunnels
• Fail a link

eth1
eth3
eth2
eth0
Control
Data

Packet Forward Engine
UmlSwitch element
Tunnel table
Click
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Whats New with VINI?

• Integration of routing w/Internet
• Better isolation
• Real topologies
• Inject events

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Controlled Realism

• Control
• Reproduce results
• Methodically change or relax constraints
• Realism
• Long-running services attract real customers
• Forward high traffic volumes (Gb/s)
• Robustly handle unexpected events