Information Technology Reference
In-Depth Information
Which router is the DR for the 192.168.0.0/24 network?
RTA
Which router is the BDR for the 192.168.0.0/24 network?
RTB
Now assume a priority of 0 on RTA. Which router is the DR for the 192.168.1.0/24 network?
RTB
What will happen if another router, RTD, joins the 192.168.0.0/24 network with a router ID of
209.165.201.9?
Nothing. Both the DR and BDR have to go down before RTD can become the DR.
More OSPF Configuration
The following exercises focus on additional OSPF configurations, including propagating a default
route, modifying the reference bandwidth for metric calculations, and modifying the OSPF intervals.
Redistributing an OSPF Default Route Exercise
In Figure 11-10, notice that RTA is now the gateway router because it provides access outside the
area. In OSPF terminology, RTA is called the
Autonomous System Boundary Router
(
ASBR
), because
it connects to an external routing domain that uses a different routing policy.
Figure 11-10
Propagating a Default Route
192.168.1.0/26
Default Route
Fa0/0
S0/0/0
DCE
S0/1/0
Address Space
192.168.1.0/24
209.165.201.2/30
RTA
ISP
209.
1
65.201.1/30
S0/0/1
DCE
S0/0/0
Static Route
RTA
Propagates
Default Route to
RTB and RTC
192.168.1.252/30
192.168.1.244/30
Public
Web Server
209.165.202.129/30
T1
T1
OSPF
Area 0
S0/0/0
DCE
192.168.1.128/26
S0/0/1
192.168.1.64/26
S0/0/0
DCE
386 kbps
Fa0/0
Fa0/0
S0/0/1
RTC
RTB
192.168.1.248/30
Each routing protocol handles the propagation of default routing information a little differently. For
OSPF, the gateway router must be configured with two commands. First, RTA will need a static
default route pointing to ISP. Document the command to configure a static default route on RTA using
the
exit-interface
argument.
RTA(config)#
ip route 0.0.0.0 0.0.0.0 serial 0/1/0
Using the
exit-interface
argument, document the command necessary to configure ISP with a static
route pointing to the 192.168.1.0/24 address space.
ISP(config)#
ip route 192.168.1.0 255.255.255.0 serial 0/0/0
