  In paper the method for estimation of available bandwidth is supposed which
does not demand the advanced utilities. Our method is based on the measurement
of network delay $D$ for packets of different sizes $W$. The simple expression
for available bandwidth $B_{av} =(W_2-W_1)/(D_2-D_1)$ is substantiated. For the
experimental testing the measurement infrastructure for Russian segment of
Internet was installed in framework of RFBR grant 06-07-89074.
