ADC CUDA 3 - Manual (Page 302)

ADC Telecommunications, Inc.
300 C HAPTER 14: C ONFIGURING IP
OSPF requires the backbone to be contiguous to all areas in the AS. All other
non-backbone areas (areas other than area 0) must have a connection to the
backbone area. Non-backbone areas that are not contiguous to the
backbone can use virtual interfaces to connect to the backbone.
OSPF Routers
OSPF performs routing within an area and routing between areas. Different
categories of routers perform these two types of routing.
Autonomous system boundary routers (ASBRs) connect an OSPF routing
domain to another routing domain (such as RIP).
Area border routers (ABRs) are linked to more than one area, or are linked
between an area and backbone. ABRs maintain separate link-state databases
of each area in which they reside.
Internal routers are directly connected within the same area, as well as
routers with interfaces connected only to the backbone.
Figure 14-2 Shows an example of OSPF routing and router classifications.
Figure 14-2 OSPF Router and Routing Classifications
RIP
Area 0
(Backbone)
Area 2 Area 1
OSPF
Routing
Domain
Area
Border
Router
Internal
Router
Internal
Router
Area
Border
Router
AS
Boundary
Router
Internal
Router
RIP
Routing
Domain
CPE ROUTER
CPE ROUTER
CPE ROUTER
CPE ROUTER
CPE ROUTER CPE ROUTER