Redes ponto a ponto OSPF

Mensagem por **bernardino** » 10 Mar 2025, 01:16

Voltar a leitura: Verificador de Sintaxe - Configurar Interfaces Passivas R2 e R3

Por padrão, os roteadores Cisco elegem um DR e BDR em interfaces Ethernet, mesmo que haja apenas um outro dispositivo no link. Você pode verificar isso com o comando show ip ospf interface, como mostrado no exemplo para G0/0/0 de R1.

Código: Selecionar todos

R1# show ip ospf interface GigabitEthernet 0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  Internet Address 10.1.1.5/30, Area 0, Attached via Interface Enable
  Process ID 10, Router ID 1.1.1.1, Network Type BROADCAST, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Enabled by interface config, including secondary ip addresses
  Transmit Delay is 1 sec, State BDR, Priority 1
  Designated Router (ID) 2.2.2.2, Interface address 10.1.1.6
  Backup Designated router (ID) 1.1.1.1, Interface address 10.1.1.5
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:08
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/2/2, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 1
  Last flood scan time is 0 msec, maximum is 0 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2  (Designated Router)
  Suppress hello for 0 neighbor(s)
R1#

R1 é o BDR e R2 é o DR. O processo de eleição DR/ BDR é desnecessário, pois só pode haver dois roteadores na rede ponto a ponto entre R1 e R2. Observe na saída que o roteador designou o tipo de rede como BROOD. Para alterar isso para uma rede ponto-a-ponto, use o comando de configuração de interface ip ospf network point-to-point em todas as interfaces nas quais você deseja desativar o processo de eleição DR/BDR. O exemplo abaixo mostra essa configuração para R1. O status de adjacência do vizinho OSPF ficará inativo por alguns milissegundos.

Código: Selecionar todos

R1(config)# interface GigabitEthernet 0/0/0
R1(config-if)# ip ospf network point-to-point
*Jun  6 00:44:05.208: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0/0 from FULL to DOWN, Neighbor Down: Interface down or detached
*Jun  6 00:44:05.211: %OSPF-5-ADJCHG: Process 10, Nbr 2.2.2.2 on GigabitEthernet0/0/0 from LOADING to FULL, Loading Done
R1(config-if)# interface GigabitEthernet 0/0/1
R1(config-if)# ip ospf network point-to-point
*Jun  6 00:44:45.532: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on GigabitEthernet0/0/1 from FULL to DOWN, Neighbor Down: Interface down or detached
*Jun  6 00:44:45.535: %OSPF-5-ADJCHG: Process 10, Nbr 3.3.3.3 on GigabitEthernet0/0/1 from LOADING to FULL, Loading Done
R1(config-if)# end
R1# show ip ospf interface GigabitEthernet 0/0/0
GigabitEthernet0/0/0 is up, line protocol is up
  Internet Address 10.1.1.5/30, Area 0, Attached via Interface Enable
  Process ID 10, Router ID 1.1.1.1, Network Type POINT_TO_POINT, Cost: 1
  Topology-MTID    Cost    Disabled    Shutdown      Topology Name
        0           1         no          no            Base
  Enabled by interface config, including secondary ip addresses
  Transmit Delay is 1 sec, State POINT_TO_POINT
  Timer intervals configured, Hello 10, Dead 40, Wait 40, Retransmit 5
    oob-resync timeout 40
    Hello due in 00:00:04
  Supports Link-local Signaling (LLS)
  Cisco NSF helper support enabled
  IETF NSF helper support enabled
  Index 1/2/2, flood queue length 0
  Next 0x0(0)/0x0(0)/0x0(0)
  Last flood scan length is 1, maximum is 2
  Last flood scan time is 0 msec, maximum is 1 msec
  Neighbor Count is 1, Adjacent neighbor count is 1
    Adjacent with neighbor 2.2.2.2
  Suppress hello for 0 neighbor(s)
R1#

Observe que a interface Gigabit Ethernet 0/0/0 agora lista o tipo de rede como POINT _TO _POINT e que não há DR ou BDR no link.

Continuar a leitura: Loopbacks e Redes Ponto a Ponto