OSPF Broadcast Networks

OSPF – Hub and spoke Topology

Dans une architecture « Hub and spoke » Frame relay, les interfaces peuvent être configurées dans 4 modes de communication OSPF :

R1(config)#int s0/0
R1(config-if)#ip ospf network ?
broadcast       Specify OSPF broadcast multi-access network
non-broadcast       Specify OSPF NBMA network
point-to-multipoint Specify  OSPF point-to-multipoint network
point-to-point      Specify OSPF point-to-point network

 

Configuration des interaces de  tous les routeurs en mode broadcast

R1#conf t
R1(config)#int s0/0
R1(config-if)#ip ospf network broadcast

Dans cette configuration, la découverte de voisins OSPF est automatique

Vérifications:

R1#show ip ospf interface s0/0
Serial0/0 is up, line protocol is up
  Internet Address 10.1.1.1/24, Area 0
  Process ID 1, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 64
  Transmit Delay is 1 sec, State DR, Priority 255
  Designated Router (ID) 1.1.1.1, Interface address 10.1.1.1
  No backup designated router on this network
  Timer intervals configured, Hello 5, Dead 20, Wait 20, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:03
  Supports Link-local Signaling (LLS)
  Index 2/2, flood queue length 0
  Next 0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 4 msec
  Neighbor Count is 3, Adjacent neighbor count is 3
    Adjacent with neighbor 2.2.2.2
    Adjacent with neighbor 3.3.3.3
    Adjacent with neighbor 4.4.4.4   
  Suppress hello for 0 neighbor(s)
R1#show ip ospf neighbor

Neighbor ID     Pri   State           Dead Time   Address         Interface
2.2.2.2           0   FULL/DROTHER    00:00:19    10.1.1.2        Serial0/0
3.3.3.3           0   FULL/DROTHER    00:00:15    10.1.1.3        Serial0/0
4.4.4.4           0   FULL/DROTHER    00:00:16    10.1.1.4        Serial0/0

Dans ce mode, les routeurs « spoke » obtiennent les IP des autres « spoke » comme next hop, la configuration frame relay doit permettre d’atteindre tous les next hop

R1#show ip route ospf
O    2.0.0.0/8 [110/65] via 10.1.1.2, 00:03:59, Serial0/0
O    3.0.0.0/8 [110/65] via 10.1.1.3, 00:03:59, Serial0/0
O    4.0.0.0/8 [110/65] via 10.1.1.4, 00:03:59, Serial0/0

R2#show ip  route ospf
O    1.0.0.0/8 [110/65] via 10.1.1.1, 00:07:11, Serial0/0
O    3.0.0.0/8 [110/65] via 10.1.1.3, 00:07:11, Serial0/0
O    4.0.0.0/8 [110/65] via 10.1.1.4, 00:07:11, Serial0/0

R3#show ip route ospf
O    1.0.0.0/8 [110/782] via 10.1.1.1, 00:07:29, Serial1/0
O    2.0.0.0/8 [110/782] via 10.1.1.2, 00:07:29, Serial1/0
O    4.0.0.0/8 [110/782] via 10.1.1.4, 00:07:29, Serial1/0

R4#show ip route ospf
O    1.0.0.0/8 [110/65] via 10.1.1.1, 00:07:46, Serial0/0
O    2.0.0.0/8 [110/65] via 10.1.1.2, 00:07:46, Serial0/0
O    3.0.0.0/8 [110/65] via 10.1.1.3, 00:07:46, Serial0/0
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