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Alteon OS Application Guide
Chapter 12: OSPF
18942C4911, January 2007
Transit Area—an area that allows area summary information to be exchanged between
routing devices. The backbone (area 0), any area that contains a virtual link to connect two
areas, and any area that is not a stub area or an NSSA are considered transit areas.
Figure 12-1 OSPF Area Types
Backbone
Area 0
Stub Area
Not-So-Stubby Area
(NSSA)
Transit Area
No External Routes
from Backbone
Stub Area, NSSA,
or Transit Area
Connected to Backbone
via Virtual Link
(Also a Transit Area)
External LSA
Routes
Internal LSA
Routes
ABR
ABR
ABR
ASBR
Non-OSPF Area
RIP/BGP AS
Virtual
Link
ABR
ABR = Area Border Router
ASBR = Autonomous System
Boundary Router