Installing and Administering Internet Services

Chapter 8 271
Configuring gated
Configuring the OSPF Protocol
Defining Backbones
The OSPF backbone distributes routing information between areas.
Backbones are defined with the same statements and clauses as areas.
The stub statement may not be defined for a backbone. The backbone
statement is used to define a router as a backbone router. If an OSPF
internal or area boarder router is also a backbone router, the backbone
statement must follow the area statement(s) in the /etc/gated.conf
file. Whenever an area border router (a router connected to multiple
areas) is configured, backbone information must be provided.
Figure 8-10 shows an example of two area border routers that form part
of a backbone. Router A has interfaces to both area 0.0.0.1 and area
0.0.0.2, while router B has interfaces to areas 0.0.0.3 and 0.0.0.4. Router
A is connected to router B through interface 15.13.115.156.
Figure 8-10 Backbone Configuration Example
The following is an example of the backbone router definition for router
A’s /etc/gated.conf file:
backbone {
interface 15.13.115.156 {
enable ;
Router A Router B
Area 0.0.0.1
Area 0.0.0.2 Area 0.0.0.4
Area 0.0.0.3
15.13.115.156