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HEN Heterogeneous Experimental Network. Felipe Huici, Adam Greenhalgh, Saleem Bhatti, Mark Handley and others Networks Research Group Department of Computer Science University College London. Overview. Problem Space Solution: HEN Current State of Development
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HENHeterogeneousExperimentalNetwork Felipe Huici, Adam Greenhalgh, Saleem Bhatti, Mark Handley and others Networks Research Group Department of Computer Science University College London
Overview • Problem Space • Solution: HEN • Current State of Development • Future Development and Research
Investigations in Network Research real experiments (test-beds) analysis simulation deployment More control More reproducible Limited applicability to real world More accurate results Fewer assumptions Increased costs / difficulty
Real Experiments as Complements to Simulation • Simulation is popular: • Easy to set-up • Easy to control/manage • (Mostly) reproducible results • Easy to produce results for large-scale networks • But: • Simulators may not reflect what happens in real life • Not adequate for all kinds of research
Real Experiments as Complements to Simulation • So … it is nice to do real experiments: • Cross-verification of simulation results • Show efficacy - show that it can work in real life!
Doing real experiments is hard • Real experiments: • Often this means building a test-bed • Building a test-bed requires: • Time • Money • Expertise/experience
Doing real experiments is hard • Using a test-bed: • Requires per experiment configuration and tuning • Often requires installation of software on each node • Doing this per experiment is often impractical • Restricts ability to test new ideas • Duplication of effort • Need a flexible, easily-configurable test-bed
Basic requirements for HEN • HEN - A “lights-out”, L2/L3-configurable network lab • Flexible L2 configuration (VLANS) • L3 configuration (IP + VPNs) • Multiple heterogeneous nodes • Remote power control • Serial console • Remote boot (PXE) • Multi-OS boot • Multiple simultaneous experiments
The Story So Far • Hardware • 9 low-end nodes, multiple interfaces each • 1 FreeBSD and 1 Linux support servers • Switches • 1 external • 1 management • 3 experimental • 2 power switches • Serial console access via one of the servers
The Story So Far • Software • Remote booting using PXE • User specifies kernel/filesystem to load • Automatic configuration of vlans • XML files store configurations • SNMP applies configurations • Scripts to allow power cycling, console access, automatic run of startup scripts • Functional but a GUI would be nice
Random Junk (HEN So Far) Non-scavenged servers! Literally scavenged from a bin Scavenged from other projects Planetlab nodes
Design Goals • Sufficient flexibility to enable interesting topologies • Sufficient heterogeneity to allow creation of hotspots • Eg: Denial-of-Service, congestion control • Isolation • Evaluate defense against real worms • Reproducibility • Eg: Easy reload of past configurations
Future HEN • Hardware • 80 nodes: 20 high-end, 40 mid-range, 20 low-end each with 10/100/1000 quad cards • 400 x 1 Gb port Ethernet switch • Commercial routers for interop testing • 15 wireless LAN 802.11 a/b/g access points • 60 MOTE and IMEC wireless sensors • Remote console servers • Remove power switches • SAN storage, server, A/C and power upgrades
Future HEN • Software • GUI to allow users to create network configurations, power cycle, etc • Account management system • Web-based calendar system for experiment reservation • Ability for nodes to run XEN
main cs.ucl.ac.uk LAN HEN Global router ssh gateway experimental VLANs experimental VLANs HEN-GLOBAL HEN-LOCAL HEN-management VLAN 0 (private IP network) HEN-management VLAN 1 (globally addressed IP network) VLAN
A Few Research Scenarios for HEN • Protocol performance experiments (transport, routing) • Traffic modelling and performance analysis • QoS/resource control analysis • BGP convergence process and route flap damping • Large-scale effects of interaction between inter-domain and intra-domain routeing • Denial of service: • what is happening? how do we spot it? effects on network? • Congestion control in the large: • synchronisation effects, stability, macro effects, etc. • Protocol/kernel development
Related Work • PlanetLab • Geographically diverse • Non-reproducible experiments • Only applicable to certain types of experiments • Emulab (netbed) • Highly-configurable, heterogeneous nodes, multi-OS boot • 100 Mbps links • No sensors, high-end router • Open Network Lab (Washington University) • Emphasis on extensible routers • 36 homogeneous nodes