Phase equilibria of a binary mixture of equal-sized network forming fluid (hard sphere diameters D-[a] = D-[b]) with associative forces between like species and hard sphere repulsion between unlike species are determined using an analytical solution of the associative Percus-Yevick integral equation. The theory shows how occurrence of coexistence lines correlates with the interparticle potential parameters, density and composition of the system. The phase behavior of the system with varying degrees and symmetry of association is studied. Namely, immiscibility curves for the mixture of chains and network-forming fluid are built and discussed.