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.








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