Basic purpose of this lecture is to present Medium Access Control Sublayer. Here major focus on the Channel Allocation Problem: Static Channel Allocation in LANs and MANs and Dynamic Channel Allocation in LANs and MANs. This lecture also briefly describe on Dynamic Channel Allocation in LANs and MANs, Multiple Access Protocols, Collision-Free Protocols, Limited-Contention Protocols, Adaptive Tree Walk Protocol, Wavelength Division Multiple Access Protocols etc.