String Network and $\mathit{U}$ Duality

We discuss the generalization of recently discovered BPS configurations, corresponding to the planar string networks, to nonplanar ones by considering the $U$-duality symmetry of type-II string theory in various dimensions. As an explicit example, we analyze the string solutions in eight-dimensional space-time, carrying SL(3) charges, and show that by aligning the strings along various directions appropriately, one can obtain a string network which preserves 1/8 supersymmetry.