TP-Link T3700G-52TQ User Manual page 221

As shown above, a large-scale network is divided into three areas: Area 0, Area 1 and Area 2.
Area 1 and Area 2 exchange the routing information via Backbone Area, which has to maintain
its network connectivity at all time. The non-backbone Area 1 and Area 2 cannot communicate
directly with each other, but they can exchange routing information through the backbone Area
0. On large-scale networks, an appropriate area partition can help greatly to save network
resources and enhance the speed of the routing.
After the area partition in the network, routers of different type need to accomplish different
tasks. Different areas need to transmit the routing information to the backbone area in different
ways, due to their different locations relative to the backbone area. In the following, we will
introduce the details involved after the area partition.
Router Type
1.
As Figure 10-35 shows, after the area partition of the network, the routers need to accomplish
different tasks due to their locations in different areas, according to which the routers can be
classified into 4 types: Internal Router (IR), Backbone Router (BR), Area Boundary Router (ABR)
and Autonomous System Boundary Router (ASBR).
Responsibilities of different routers divide as Table 10-2.
Router Features
Name
IR All the
interfaces
to the same area
BR At least one routing
interface
to the backbone
area
ABR Connect
more areas to the
backbone area
Figure 10-35 Classification of Routers
Responsibility
routing Flood and exchange its all link and interface information
belong with the adjacent routers in the same area, thus to
synchronize the link state database with the intra-area
routers.
Summarize the routing topology information from all areas
belongs in AS via ABR and forward the communication data for all
areas.
one or Maintain independent link state databases for different
areas, and deliver the topology information of each area to
the other areas via the backbone area.
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