CCIE Routing & Switching V5:ISIS Adjacency - L1-L2

ISIS has a 2 layer hierarchy Level-2 (the backbone) Level-1 (the areas) IS-IS support three type of router levels Level-1 (L1) router (intra-area routing) Level-2 (L2) router (inter-area routing) Level-1-2 (L1L2) router (intra and inter-area routing) Manually we can define IS-type. If not defined Default is level 1/Level 2