OSPF areas

FIGURE 7 . 1
OSPF areas
OSPF area boundaries fall within a router. These routers are known as ABRs. OPSF ABRs
are allowed to have multiple interfaces in different areas. Also notice that the backbone area for
OSPF must be numbered as Area 0. One last item to remember about OSPF is that if an area is
not set up as a totally stubby area, summary LSAs will be sent into the area. This means that all
routers in that particular area will know about inter-area routes. With all of this in mind, let’s
take a look at the same topology, except this time it’s running IS-IS as the routing protocol.
Refer to Figure 7.2.