Issue with the sampling rate

Hi all

i'm using USRP1 Ver 4.5. i'm trying to establish communication

between USRPs with the test code provided by Ettus R… I could do
the data transfer between USRPs with the default rate of 100 kbps using
your benchmark programs ( and But when
I tried to reduce the rate to less that 35 kbps the data rate does not
get reduced. i’m not sure if it the limitation of the hardware or any
other configuration has to be changed to make it work.
It would be great if you could help me with the issue.