OSPF network type point-to-multipoint is the RFC standard. the some feature of OSPF P2M are:
- Need Same subnet
- no need to configure static neighbours
- No DR/BDR
- Less PVCs required
I use a simple frame-relay topology for configuring OSPF point-to-multipoint on gns3. I use the c7200 IOS for this lab. Configure the topology as below:
GNS3 Frame-Relay switch Configuration:
Add the mapping as shown in figure for given topology.
R1 Configuration:
R1(config)# interface Serial1/0
R1(config-if)# ip address 10.1.1.1 255.255.255.0
R1(config-if)# encapsulation frame-relay
R1(config-if)# ip ospf network point-to-multipoint
R1(config-if)# ip ospf 1 area 0
R1(config)# frame-relay map ip 10.1.1.2 200 broadcast
R1(config)# frame-relay map ip 10.1.1.3 300 broadcast
R1(config)# router ospf 1
R1(config-router)# router-id 1.1.1.1
R2 Configuration:
R2(config)# interface Serial1/0
R2(config-if)# ip address 10.1.1.2 255.255.255.0
R2(config-if)# encapsulation frame-relay
R2(config-if)# ip ospf network point-to-multipoint
R2(config-if)# ip ospf 1 area 0
R2(config)# exit
R2(config)# frame-relay map ip 10.1.1.1 100 broadcast
R2(config-if)# interface Loopback1
R2(config-if)# ip address 200.1.1.1 255.255.255.0
R2(config-if)# ip ospf 1 area 0
R2(config)# router ospf 1
R2(config-router)# router-id 2.2.2.2
R3 Configuration:
R3(config)# interface Serial1/0
R3(config-if)# ip address 10.1.1.3 255.255.255.0
R3(config-if)# encapsulation frame-relay
R3(config-if)# ip ospf network point-to-multipoint
R3(config-if)# ip ospf 1 area 0
R3(config)# exit
R3(config)# frame-relay map ip 10.1.1.1 100 broadcast
R3(config)# router ospf 1Verifications:
"Show ip route" on all routers you should have all 3 OSPF routes.
Show Ip ospf neig: No DR/BDR in output
On all router sh ip ospf 1 interface s1/0 network type is P2M.
