NBMA

Topology

Objectives

OSPF Over NBMA - 5 Modes

Tunning OSPF

Modes

RFC Standard

NON_BROADCAST (NBMA)

• Default on Framrelay multipoint

• Static neighbor 

• DR/BDR

• Static framrelay mapping

POINT_TO_MULTIPOINT

• No DR/BDR

• Dynamic Framrelay mapping

CISCO Proprietary 

BROADCAST

• Full Mesh required

• DR/BDR

POINT_TO_POINT

• Default for Framrelay Point-to-point

• No DR/BDR

POINT_TO_MULTIPOINT

Same as RFC Point-to-multipoin

Static neighboR

Framrelay Configuration

Router 1

interface Serial0/0

 no ip address

 encapsulation frame-relay

 clock rate 2000000

 no arp frame-relay

 no frame-relay inverse-arp

!

interface Serial0/0.1 multipoint

 ip address 170.100.100.1 255.255.255.0

 frame-relay map ip 170.100.100.2 102 broadcast

 frame-relay map ip 170.100.100.3 103 broadcast

 no frame-relay inverse-arp

Router 2

interface Serial0/0

 ip address 170.100.100.2 255.255.255.0

 encapsulation frame-relay

 frame-relay map ip 170.100.100.1 201 broadcast

 frame-relay map ip 170.100.100.3 201 broadcast

 no frame-relay inverse-arp

 no arp frame-relay

NON_BROADCAST mode does not take care of socks connectivity

Router 3

interface Serial0/0

 ip address 170.100.100.3 255.255.255.0

 encapsulation frame-relay

 frame-relay map ip 170.100.100.1 301 broadcast

 frame-relay map ip 170.100.100.2 301 broadcast

 no frame-relay inverse-arp

 no arp frame-relay

NON_BROADCAST mode does not take care of socks connectivity

Router 4

interface Serial0/0

 ip address 170.100.200.2 255.255.255.252

 encapsulation frame-relay

 frame-relay map ip 170.100.200.1 401 broadcast

 no frame-relay inverse-arp

 no arp frame-relay

Configuration for Area 2,3 and 4

Router 2

interface FastEthernet0/0

 ip address 170.100.2.1 255.255.255.0

router ospf 1

 router-id 2.2.2.2

 network 170.100.2.1 0.0.0.0 area 2

Router 3

interface FastEthernet0/0

 ip address 170.100.3.1 255.255.255.0

router ospf 1

 router-id 2.2.2.2

 network 170.100.3.1 0.0.0.0 area 2

Router 4

interface FastEthernet0/0

 ip address 170.100.4.1 255.255.255.0

router ospf 1

 router-id 2.2.2.2

 network 170.100.4.1 0.0.0.0 area 2

NON_BROADCAST

Router 1

router ospf 1

 router-id 1.1.1.1

 network 170.100.100.1 0.0.0.0 area 0

 neighbor 170.100.100.3

 neighbor 170.100.100.2

Statically add neighbor on the hub side

Router 2

router ospf 1

 router-id 2.2.2.2

 network 170.100.2.1 0.0.0.0 area 2

 network 170.100.100.2 0.0.0.0 area 0

Router 3

router ospf 1

 router-id 3.3.3.3

 network 170.100.3.1 0.0.0.0 area 3

Making Router 1 the DR

Router 1

interface Serial0/0.1 multipoint

 ip ospf priority 255

Router 2

interface Serial0/0

 ip ospf priority 0

Router 3

interface Serial0/0

 ip ospf priority 0

Verification

R2#show ip ospf int

Serial0/0 is up, line protocol is up

  Internet Address 170.100.100.2/24, Area 0

  Process ID 1, Router ID 2.2.2.2, Network Type NON_BROADCAST, Cost: 64

  Transmit Delay is 1 sec, State DROTHER, Priority 0

  Designated Router (ID) 1.1.1.1, Interface address 170.100.100.1

  No backup designated router on this network

  Timer intervals configured, Hello 30, Dead 120, Wait 120, Retransmit 5

    oob-resync timeout 120

    Hello due in 00:00:25

R3#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface

1.1.1.1         255   FULL/DR         00:01:51    170.100.100.1   Serial0/0

POINT_TO_POINT (Router 1 & 4)

Router 1

interface Serial0/0.2 point-to-point

 ip address 170.100.200.1 255.255.255.252

router ospf 1

 router-id 1.1.1.1

 network 170.100.200.1 0.0.0.0 area 0

Router 4

interface Serial0/0

 ip ospf network point-to-point

Configure interface for Point-to-point mode

router ospf 1

 router-id 4.4.4.4

 network 170.100.200.2 0.0.0.0 area 0

POINT_TO_MULTIPOINT