Transcript Construction and Evaluation of a WMN Testbed - WINSLab

Construction and Evaluation of a WMN
Testbed
from “Guide to WMNs” by Sudip Misra and et al,
2009
Myungchul Kim
[email protected]
Introduction
• MANET: the network is made of user devices only and no
infrastructure exits
• WMN
• MIT Roofnet, Microsoft Research’s testbed: inflexible in
terms of scenario creation, repeatability and controllability
• UMIC-Mesh.net: combines a real testbed and a virtualizated
environment to study WMNs
WMNs
• System and network architecture
– Mesh gateways
– Mesh routers
– Routing mesh clients and non-routing mesh clients
• Network characteristics
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Wireless
Multi-hop
Redundancy
Mobility
Dynamics: self-organizing, self-healing, selfconfiguration
– Static infrastructure
– Integration
How to study WMNs
• Theoretical analysis
• Simulation
– Study effects of certain parameters on the network
performance
– Disadv:
• Emulation
– Existing hardware and real network layers or parts, and a
simulated environment
How to study WMNs
• Virtualization
1. System virtualization with the virtual machine monitor
allowing an unmodified OS for a completely different
CPU
2. VMM is underneath the host OS: allow multiple OSes
3. The OS-level virtualization
– Adv: software development can be done on real
machines with a real OS, and tested on the virtual
network of VM
• Real testbeds
How to study WMNs
• Summary
UMIC-Mesh.net: a hybrid testbed for
WMNs
• Motivation for a hybrid testbed
– The virtualized environment: the developing task
(implementation and debugging), the validation, and the
functionally testing, e.g., booting and compiling at mesh
routers
– Performance evaluation: real testbed
UMIC-Mesh.net: a hybrid testbed for
WMNs
• System and network architecture
UMIC-Mesh.net: a hybrid testbed for
WMNs
• Testbed realization
– RWTH Aachen University
– Hardware
• 51 mesh routers
• A backbone mesh router: a single board computer, two
identical IEEE 802.11a/b/g based on Atheros AR5213 XR
and two omnidirectional antennas
• The first NIC in channel 1 and the second one in channel
11
UMIC-Mesh.net: a hybrid testbed for
WMNs
• Testbed realization
– Software
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Ubuntu Linux
WLAN driver: madwifi-ng
Virtualization environment: VMM XEN
Wireless medium emulation: NetEm
DYMO and OLSR
Performance evaluation
• OLSR
– Link-state routing protocol
– MPR
• Methodology
Performance evaluation
• Methodology
– Ping test: the packet loss ration and the average hop count
• 50 MTU sized packets at a rate of five packets per second
– Flowgrind test: TCP throughput
• Lasting 15s with the TCP congestion control NewReno
TCP
– To copy with environmental influences: one
measurement was run sequentially over all mentioned
paths. Repeated for 30 times
Performance evaluation
• Flowgrind
– Split the data and control connection
– Reports throughput, round trip time, inter-arrival time
and Linux kernel variables of TCP connections
(congestion window, slow start threshold, number of
bytes unacknowledged in the network, …)
• Measurement discussion
– The OLSR messages causes a non-negligible amount of
interference and thereby lower the overall performance
Performance evaluation
• Measurement discussion
Performance evaluation
• Measurement discussion
Performance evaluation
• Measurement discussion
Related work
• Existing testbeds
Related work
• Existing testbeds
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Click modular router
DHCP
DSR
Linksys WRT54G: OpenWRT
AODV
IPv6
Mobile IP