Type-I collagen is the most abundant protein in animals. In connective tissues, type-I collagen self-assembled into fibrous network, whose mechanical properties have been shown to be closely related with diseases, inflammation and cancer. The existing mechanical characterization of the collagen fiber networks has been focusing on scales larger compared with their pore sizes, revealing their nonlinear rheology such as strain-stiffening. However, we argue this is not the relevant scale of cell mechanosensing. We have therefore measured the micromechanical properties of reconstituted collagen gel at scales below the pore size using holographic optical tweezers. We have found rich mechanical properties that violates the continuum media assumption. In addition to report these experiment findings, I will also talk about our progress in numerical models to understand the relation between micromechanics and microstructure of a general biopolymer network.