The structure and dynamics of confined polymer between adjacent filler particles is addressed, forming glassy-like polymer bridges between adjacent filler particles. They play a key role in understanding the mechanical properties of filler-reinforced elastomers. It is demonstrated that several aspects of linear and non-linear viscoelasticity of filled rubbers can be traced back to the specific rate and temperature dependent properties of these filler-filler bonds. Since they consist of immobilized polymer they are quite stiff, transmitting the stress between adjacent particles of the filler network. Accordingly, the response of the filler network is viscoelastic in nature, which has consequences for the small strain modulus and the construction of viscoelastic master curves. The pronounced non-linear behavior of filled elastomers is related to the rupture of glassy-like polymer bridges, which deform under strain and break if a critical strain is exceeded. The rupture mechanism is modelled analytically in the frame of a microstructure-based model of rubber reinforcement, denoted Dynamic Flocculation Model. It describes the mechanical response due to cyclic breakdown and re-aggregation of tender filler clusters connected by glassy-like polymer bridges. This provides a microscopic understanding of the complex stress-strain properties during repeated, quasi-static loading up to large strains, i.e. the well-known filler induced stress softening and hysteresis effects. Based on evaluated material parameters, various energy dissipation mechanisms are discussed for elastomer systems filled with carbon black (CB) and graphene nano-platelets (GNP), respectively. The latter carbon-based nano-fillers provide a promising performance regarding mechanical strength, hysteresis and tribological properties.