Totally stubby is a cisco nob that takes the concept of a stub area a step further.
In a stub area, only LSA types 1 (router) 2 (network) and 3 ( summary) flow within the
area. Hence, no routing information concerning prefixes outside of the OSPF domain is
injected into the area. In a totally stubby area, the flow of normal type 3 LSA's is
halted as well. This leaves the area with no information about any prefixes outside
of the area. In order to allow traffic to exit the area, a single type 3 LSA is
propagated by each ABR which advertises a default route. The default cost nob simply
allows you to set a cost for the route instead of using the standard OSPF metric to
the ABR itself.
Hope this helps some
Pete
*********** REPLY SEPARATOR ***********
On 11/08/2000 at 4:29 PM Bob Hunter wrote:
>Hi,
> I'm confused on the subject of totally stubby areas, and the command "area
>default-cost". From what I'm reading, one of the qualifications of a totally
>stubby area is that if multiple exits (ABRs) exist, routing to outside the
>area does not have to take an optimal path. Does this mean that each router
>within the area picks the closest ABR as the gateway to everything outside
>the area, and that there is no way to control the default route? If so, does
>that imply that the area default-cost is used for incoming routes? Would
>incoming routes even exits if the area was a totally stubby area?
>
> I would very much appreciate it if someone would please set me straight.
>
> Thank you.
>
>Bob Hunter, CCNA, CNE
>
>
>
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