Symmetric even graphs have these properties. For every x there exists a unique antipodal vertex. And all vertices have the same eccentricity the diameter of G.
It is hard to answer. With my viewpoints in my paper, Symmetric graphs firstly the potentials of each unit subgraph are equal. And Then n is an even number. While you partition graph with any vertex as the start one, you would obtain a result with same datastructe, which is "symmetric" for low and hight regions. I observe such few cases only.