OBJECTIVE:
1. Understand why DR & BDR is no longer required for a Point-to-Multipoint OSPF network
2. Determine the steps on how to configure Point-to-Multipoint OSPF network.
3. To understand that the default behavior of point-to-multipoint OSPF Network over a frame relay
network is broadcast
Here are the configurations of the three routers as per the topology above,
MANILA Router Configurations:
MANILA#sh run | sec ospf
ip ospf network point-to-multipoint
router ospf 1
network 10.10.10.0 0.0.0.255 area 0
network 192.168.12.0 0.0.0.255 area 0
MANILA#
MANILA#sh run int s2/0
Building configuration…
Current configuration : 154 bytes
!
interface Serial2/0
ip address 192.168.12.1 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint <<<< This command select which OSPF network type were used.
serial restart-delay 0
end
MANILA#sh run int lo0
Building configuration…
Current configuration : 64 bytes
!
interface Loopback0
ip address 10.10.10.1 255.255.255.0
end
MELBOURNE Router Configurations:
MELBOURNE#sh run | section ospf
router ospf 1
network 20.20.20.0 0.0.0.255 area 0
network 192.168.12.0 0.0.0.255 area 0
MELBOURNE#sh run int s2/0
Building configuration…
Current configuration : 191 bytes
!
interface Serial2/0
ip address 192.168.12.2 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint <<<< This command select which OSPF network type were used.
serial restart-delay 0
frame-relay map ip 192.168.12.3 202 broadcast
end
MELBOURNE#sh run int lo0
Building configuration…
Current configuration : 64 bytes
!
interface Loopback0
ip address 20.20.20.1 255.255.255.0
end
SINGAPORE Router Configurations:
SINGAPORE#sh run int s2/0
Building configuration…
Current configuration : 191 bytes
!
interface Serial2/0
ip address 192.168.12.3 255.255.255.0
encapsulation frame-relay
ip ospf network point-to-multipoint
serial restart-delay 0
frame-relay map ip 192.168.12.2 203 broadcast
end
SINGAPORE#sh run int lo0
Building configuration…
Current configuration : 64 bytes
!
interface Loopback0
ip address 30.30.30.1 255.255.255.0
end
SINGAPORE#sh run | sec ospf
ip ospf network point-to-multipoint
router ospf 1
network 30.30.30.0 0.0.0.255 area 0
network 192.168.12.0 0.0.0.255 area 0
SINGAPORE#
VERIFICATIONS: Now, let’s check the status of the Routing table of the three routers.
MANILA#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
30.30.30.1 0 FULL/ – 00:01:50 192.168.12.3 Serial2/0
20.20.20.1 0 FULL/ – 00:01:53 192.168.12.2 Serial2/0
MANILA#
MELBOURNE#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 0 FULL/ – 00:01:53 192.168.12.1 Serial2/0
MELBOURNE#
SINGAPORE#sh ip ospf neighbor
Neighbor ID Pri State Dead Time Address Interface
10.10.10.1 0 FULL/ – 00:01:52 192.168.12.1 Serial2/0
SINGAPORE#
>>> This output shows that even though, we have a point-to-multipoint topology, the behavior is a point-to-point. There was neither any DR or BDR election that happens.
Further verifications using Ping and Traceroutes shows that our configurations are correct.
SINGAPORE#ping 20.20.20.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 20.20.20.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 52/68/116 ms
SINGAPORE#
MELBOURNE#ping 30.30.30.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 30.30.30.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 52/59/76 ms
MELBOURNE#
SINGAPORE#traceroute 20.20.20.1
Type escape sequence to abort.
Tracing the route to 20.20.20.1
VRF info: (vrf in name/id, vrf out name/id)
1 192.168.12.1 60 msec 56 msec 52 msec
2 192.168.12.2 88 msec 56 msec 52 msec
SINGAPORE#
NOTE:
For OSPF Point-to-Multipoint configurations, it’s a BROADCAST by default but we have to manually map the frame relay networks as Broadcast for MELBOURNE & SINGAPORE routers only because they have no direct connectivity to each other. The traffic between the two have to go through MANILA router.
MANILA(config-if)#ip ospf network point-to-multipoint ?
non-broadcast Specify non-broadcast point-to-mpoint network
MANILA(config-if)#ip ospf network point-to-multipoint
NETWORK LESSON 
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