  The TOTEM experiment with its detectors in the forward region of CMS and the
Roman Pots along the beam line will determine the total pp cross-section via
the optical theorem by measuring both the elastic cross-section and the total
inelastic rate. TOTEM will have dedicated runs with special high-beta* beam
optics and a reduced number of proton bunches resulting in a low effective
luminosity between 1.6 x 10^{28} cm^{-2} s^{-1} and 2.4 x 10^{29} cm^{-2}
s^{-1}. In these special conditions also an absolute luminosity measurement
will be made, allowing the calibration of the CMS luminosity monitors needed at
higher luminosities. The acceptance of more than 90 % of all leading protons in
the Roman Pot system, together with CMS's central and TOTEM's forward detectors
extending to a maximum rapidity of 6.5, makes the combined CMS+TOTEM experiment
a unique instrument for exploring diffractive processes. Scenarios for running
at higher luminosities necessary for hard diffractive phenomena with low
cross-sections are under study.
