Point-to-Point Serial-Link Configuration
The IS-IS configuration for point-to-point links is the most commonly used in real networks, for point-to-point serial interfaces, as well as to NBMA point-to-point subinterfaces. The point-to-point configuration lends itself to various advantages because it provides congruency to the underlying physical topology. Figures 9-1 and 9-2 depict a simple point-to-point setup of two routers (RT1 and RT2) connected directly by a serial link. The routers are in the same IS-IS area in Figure 9-1 but in different areas in Figure 9-2.