230 Chapter 7: OSPF, EIGRP, and IGRP
Figure 7-8 illustrates OSPF stubby areas, and Table 7-2 discusses them in more detail.
Figure 7-8
OSPF Stubby Areas
Determining OSPF Convergence
When a change occurs in the network, it is the responsibility of the routing protocol to reroute
traffic quickly. Convergence time defines the time it takes a router to recognize and recalculate
Table 7-2
OSPF stubby areas
Area Type
Interarea
Intra-area
External
Default
Stub
Yes
Yes
No
Yes
Totally stubby
No
Yes
No
Yes
Not-so-stubby
No
Yes
Yes
NSSA has no External
Type 5 route.
Yes
Backbone area 0
Area border router
Area 1
Summary LSAs
Specific LSAs
Default external 0.0.0.0
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