1. ModelNet: A Large-Scale Network Emulator for Wireless Networks Priya Mahadevan, Ken Yocum, and Amin Vahdat Duke University,
Goal: To subject unmodified wireless applications using distributed emulation to realistic mobile and ad hoc scenarios
Motivation
ModelNet Architecture
Current techniques for evaluating wireless applications
Simulation
Limited scalability, need to rewrite applications for the simulator, leave out important details of the system
Live deployment
limited in size, not reproducible, hard to isolate faults
Emulation
static, small scale, hard to configure
Our Requirements
Combine advantages of live deployment and simulation
Support large scale applications
Run unmodified applications on unmodified OS’s
Reproducible behavior
Allow movement patterns during the experiment
Modelnet Cores
Responsible for routing packets and performing the actual emulation
Edge nodes
Run user-level services
Pipes
Are used for emulation , have bandwidth, loss-rate and latencies associated with it
Virtual Nodes
Have an IP address and corresponding location in the emulated topology
Implementing ad hoc protocols
ModelNet Usage
Core keeps track of all the routing info for each VC
Core simulates the effect of the routing protocols by generating and handling all route requests/updates and broadcast packets
Creation
Generate initial mobile/adhoc topologies
Assignment
Assign pipes to ModelNet cores
Binding
Assign VN to edge nodes, bind physical nodes to cores
Execution
Execute target applications
Wireless Environment Emulation
Initial Results
On any topology change, determine new routes and neighbor sets for each node
Insert dummy packets into the queues of all nodes within range of a transmitting node to capture bandwidth sharing inherent to the broadcast medium
All packets from A to B consume bandwidth at all the neighboring nodes of A as well as B. This is unlike wired networks where bandwidth is consumed only at the link connecting nodes A and B
Ad hoc Scenario
Square with side 670m, 50 mobile hosts with random start points
Implement the “random wavepoint” model
Future Research
Emulating MAC layer
Implementing various ad hoc routing protocols in ModelNet core