  The Kuiper belt includes tens of thousands of large bodies and millions of
smaller objects. The main part of the belt objects is located in the annular
zone between 39.4 au and 47.8 au from the Sun, the boundaries correspond to the
average distances for orbital resonances 3:2 and 2:1 with the motion of
Neptune. One-dimensional, two-dimensional, and discrete rings to model the
total gravitational attraction of numerous belt objects are considered. The
discrete rotating model most correctly reflects the real interaction of bodies
in the Solar system. The masses of the model rings were determined within
EPM2017---the new version of ephemerides of planets and the Moon at IAA
RAS---by fitting spacecraft ranging observations. The total mass of the Kuiper
belt was calculated as the sum of the masses of the 31 largest trans-neptunian
objects directly included in the simultaneous integration and the estimated
mass of the model of the discrete ring of TNO. The total mass is $(1.97 \pm
0.30)\cdot 10^{-2} \ m_{\oplus}$. The gravitational influence of the Kuiper
belt on Jupiter, Saturn, Uranus and Neptune exceeds at times the attraction of
the hypothetical 9th planet with a mass of $\sim 10 \ m_{\oplus}$ at the
distances assumed for it. It is necessary to take into account the
gravitational influence of the Kuiper belt when processing observations, and
only then to investigate residual discrepancies to discover a possible
influence of a distant large planet.
