Tutorial OSPF point-to-multipoint configuration on Gns3:

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 1
Verifications:


"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.