Documentation | !virtualMobility

Virtual Mobility and Arbitrary Topologies

The ORBIT lab has several tools to support the creation of arbitrary topologies and mobility. The first is a series of interference generators, and the second is a system of virtual 'off-grid' nodes that can have their packets sent/received from an arbitrary node in the grid. This approach can be used to create a 'step-like' mobility.

The method described here is a third way. It is implemented as a modification to the madwifi driver. Basically what it does is allows incoming packets to be filtered by sending MAC address. These filtered packets can have an arbitrary RSSI assigned to them and an arbitrary percent of these incoming packets can be ignored in order to simulate a poor radio environment.

Using the Filter

The format for the command looks like this: iwpriv orbitfilter [MAC] [PERCENT_RECEIVED] [RSSI]

an example where 75% of packets for a radio with MAC address 00:60:b3:25:c0:27 are allowed through and the RSSI is set to 55.

node1-2:~# iwpriv ath1 orbitfilter 0x00 0x60 0xb3 0x25 0xc0 0x27 75 55

to remove a filter completely, simply set the percent and RSSI to 0xFF.

node1-2:~# iwpriv ath1 orbitfilter 0x00 0x60 0xb3 0x25 0xc0 0x27 0xFF 0xFF

If you wish to set a global filter for all nodes that do not have a specific filter, simply use a MAC address with all bits set. The following example blocks packets from all nodes that do not have a specific filter.

node1-2:~# iwpriv ath1 orbitfilter 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0 0

Removing the global filter works the same way as removing a specific filter.

node1-2:~# iwpriv ath1 orbitfilter 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF 0xFF

If you wish to clear all filters, both specific and global, use this command.

node1-2:~# iwpriv ath1 orbitfilter_rst 1