Can NS3 EMU be applied on different machines in WAN?

Question

we are currently considering whether ns3 satisfying our requirements, we're looking for a convenient tool to run in distributed devices in the real network (every kind of possible connections) and capture the network performance data (like a sniffer). I realize that the primary purpose of ns3 is to simulate network topology in a single machine, but its emu module sounds promising and the flow monitor can save our effort on data capture.

In the following link

http://www.nsnam.org/wiki/HOWTO_make_ns-3_interact_with_the_real_world

it is declared that NS-3 EMU can be applied to inject simulated nodes interacting with real live network, and 3 kinds of testbed are given. However the first solution, virtual machine vmware testbed is still woking within LAN -- in promiscuous mode the virtual machines network card are listening to all LAN broadcasts so that the emu-udp-echo server and client can find each other.

My question is, is it possible that the emu-udp-echo server/client running in different, physical systems from different positions in wide network?

e.g. in different cities or from different network providers, given ip address of the hardware where the other ns-3 node is running? if it is possible, how can i specify the "real" ip address and port for the node, instead of assign a virtual ipv4 address?

Thanks a lot.

Answer 1

Yes, while the documentation describes how to perform this using virtual machines, this can be done in general on real hardware. Since that HOWTO was written, there has been additional work on providing helpers for running this type of experiment, including running on PlanetLab testbed machines. This documentation describes the generalized file descriptor NetDevice, added to the ns-3.17 release: http://www.nsnam.org/docs/release/3.19/models/html/fd-net-device.html. A similar example to the one described in that HOWTO is found in the file fd-emu-udp-echo.cc.

When using emulation mode on real networks, configuration of the MAC addresses and IP addresses must be done carefully. First, the device must be able to be put into promiscuous mode. Second, the MAC address needs to be different than the hardware address of the NIC. If you intend to be riding on top of an active NIC with existing IP address (in use for other Internet traffic), you'll need to have another IP address for ns-3 that is within the right link subnet. If instead you want to dedicate the NIC to ns-3 use, then do not assign the IP address to the host NIC and just assign it to the ns-3 configuration.

The PlanetLab example also shows another configuration that uses Tap devices to send data to/from PlanetLab testbed nodes. Some of this configuration is specific to how PlanetLab works, but the use of Tap device bridged to an ns-3 device may also facilitate emulation.