There is no relief operation similar to another. Nature, number and incentives of stakeholders vary tremendously from one operation to another, and so do the collaboration modes. One thing is always true thought: for each disaster, collaboration networks are implemented on both global and local levels. Yet, lack of collaboration is often underlined as a major weakness of humanitarians. Practitioners have therefore recently focused on this issue in order to find improvement paths. This paper, using a review of existing academic literature as well as reports published by practitioners, illustrates how collaborative networks are designed in the humanitarian sector. A panorama of existing collaboration networks during and in-between relief operations is presented. Barriers and enablers to implement them are made explicit. Two frameworks are finally proposed to better understand collaboration modes at a local level on one hand, and collaboration protocols at a global level on the other hand.