Trabalho prático 8 - OSPF

Considere o seguinte cenário de rede:

Baixar arquivo - packet tracer

Tem disponíveis as seguintes redes para atribuir aos equipamentos:

• LAN0 e LAN1: 192.168.0.0 /16
• LAN2 e LAN3: 172.16.0.0 /16
• Entre Routers: 10.0.0.0 /24

Efetue a divisão em sub-redes, de modo a garantir que cada uma redes pode conter o seguinte número de hosts:

• LAN0: 500 Host
• LAN1: 200 Host
• LAN2: 200 Host
• LAN3: 500 Host

Implemente o cenário no simulador e configure os equipamentos. Utilize o OSPF como protocolo de routing.

Verifique os seguintes pontos:

• As rotas escolhidas por cada um dos routers é o esperado?
• Verifique a métrica de cada uma das redes.
• O que acontece quando a ligação IPS0 e ISP1 é quebrada?
• Altere a largura de banda (usando o comando clock rate) das linhas entre os routers e verifique como é que o custo das rotas é afetado.
• É possível alterar a informação de largura de banda das ligações de modo a que os routers selecionem uma rota diferente das escolhida inicialmente?

Divisão em sub-redes

LANs

LAN	Rede	IPs livres	Broadcast	Gateway
LAN 0 (500 hosts)	192.168.0.0 /23	(255.255.254.0)	1 - .1.254	192.168.1.255
LAN 1 (200 hosts)	192.168.2.0 /24	(255.255.255.0)	1 - 254	192.168.2.255
LAN 2 (200 hosts)	172.16.0.0 /24	(255.255.255.0)	1 - 254	172.16.0.255
LAN 3 (500 hosts)	172.16.2.0 /23	(255.255.254.0)	2.1 - 3.254	172.16.3.255

Routers links

Link	Rede	IPs livres	Broadcast	Serial
ISP 0 - R0	10.0.0.0 /30 (255.255.255.252)	1 - 2	10.0.0.3	0/0/0 - 0/0/0
ISP 0 - ISP1	10.0.0.4 /30 (255.255.255.252)	5 - 6	10.0.0.7	0/0/1 - 0/0/0
ISP 1 - R1	10.0.0.8 /30 (255.255.255.252)	9 - 10	10.0.0.11	0/0/1 - 0/0/0
ISP 2 - R0	10.0.0.12 /30 (255.255.255.252)	13 - 14	10.0.0.15	0/0/0 - 0/0/1
ISP 2 - R1	10.0.0.16 /30 (255.255.255.252)	17 - 18	10.0.0.19	0/0/1 - 0/0/1

Configurar os IPs

Router ISP 0

Router>enable
Router#configure terminal
Router(config)#hostname ISP0
ISP0(config)#interface serial 0/0/0
ISP0(config-if)#ip address 10.0.0.1 255.255.255.252
ISP0(config-if)#clock rate 64000
ISP0(config-if)#no shutdown

ISP0(config-if)#interface serial 0/0/1
ISP0(config-if)#ip address 10.0.0.5 255.255.255.252
ISP0(config-if)#clock rate 64000
ISP0(config-if)#no shutdown
ISP0(config-if)#end

Router ISP 1

Router>ena
Router>enable
Router#configure terminal

Router(config)#hostname ISP1
ISP1(config)#interface serial 0/0/0
ISP1(config-if)#ip address 10.0.0.6 255.255.255.252
ISP1(config-if)#no shutdown

ISP1(config-if)#interface serial 0/0/1
ISP1(config-if)#ip address 10.0.0.9 255.255.255.252
ISP1(config-if)#clock rate 64000
ISP1(config-if)#no shutdown

ISP1(config-if)#end

Router ISP 2

Router>enable
Router#configure terminal
Router(config)#hostname ISP2
ISP2(config)#interface serial 0/0/0
ISP2(config-if)#ip address 10.0.0.13 255.255.255.252
ISP2(config-if)#clock rate 64000
ISP2(config-if)#no shutdown

ISP2(config-if)#interface serial 0/0/1
ISP2(config-if)#ip address 10.0.0.17 255.255.255.252
ISP2(config-if)#clock rate 64000
ISP2(config-if)#no shutdown

ISP2(config-if)#end

Router R0

Router> enable
Router# configure terminal
Router(config)# hostname R0

R0(config)# interface serial 0/0/0
R0(config-if)# ip address 10.0.0.2 255.255.255.252
R0(config-if)# no shutdown

R0(config)# interface serial 0/0/1
R0(config-if)# ip address 10.0.0.14 255.255.255.252
R0(config-if)# no shutdown

R0(config-if)# exit

R0(config)# interface fastEthernet 0/0
R0(config-if)# ip address 192.168.1.254 255.255.254.0
R0(config-if)# no shutdown

R0(config-if)# interface fastEthernet 0/1
R0(config-if)# ip address 192.168.2.254 255.255.255.0
R0(config-if)# no shutdown

R0(config-if)# end

Router R1

Router> enable
Router# configure terminal
Router(config)# hostname R1

R1(config)# interface serial 0/0/0
R1(config-if)# ip add 10.0.0.10 255.255.255.252
R1(config-if)# no shutdown

R1(config-if)# interface serial 0/0/1
R1(config-if)# ip add 10.0.0.18 255.255.255.252
R1(config-if)# no shutdown

R1(config-if)# exit

R1(config)# interface fastEthernet 0/0
R1(config-if)# ip address 172.16.0.254 255.255.255.0
R1(config-if)# no shutdown

R1(config-if)# interface fastEthernet 0/1
R1(config-if)# ip address 172.16.3.254 255.255.254.0
R1(config-if)# no shutdown

R1(config-if)# end

Configurar protocolo OSPF

Router R0

R0# enable
R0# configure terminal

R0(config)# router ospf 100
R0(config-router)# exit

R0(config)# interface serial 0/0/0
R0(config-if)# ip ospf 100 area 0
R0(config-if)# interface serial 0/0/1
R0(config-if)# ip ospf 100 area 0

R0(config-if)# exit

R0(config)# interface fastEthernet 0/0
R0(config-if)# ip ospf 100 area 0
R0(config-if)# interface fastEthernet 0/1
R0(config-if)# ip ospf 100 area 0

R0(config-if)# exit
R0(config)# router ospf 100
R0(config-router)# passive-interface fastEthernet 0/0
R0(config-router)# passive-interface fastEthernet 0/1

R0(config-router)# end

Router R1

R1> enable
R1# configure terminal

R1(config)# router ospf 100
R1(config-router)# exit

R1(config)# interface serial 0/0/0
R1(config-if)# ip ospf 100 area 0
R1(config-if)# interface serial 0/0/1
R1(config-if)# ip ospf 100 area 0

R1(config-if)# exit

R1(config)# interface fastEthernet 0/0
R1(config-if)# ip ospf 100 area 0
R1(config-if)# interface fastEthernet 0/1
R1(config-if)# ip ospf 100 area 0

R1(config-if)# exit

R1(config)# router ospf 100
R1(config-router)# passive-interface fastEthernet 0/0
R1(config-router)# passive-interface fastEthernet 0/1
R1(config-router)# end

Router ISP 0

ISP0> enable
ISP0# configure terminal
ISP0(config)# router ospf 100

ISP0(config-router)# exit

ISP0(config)# interface serial 0/0/0
ISP0(config-if)# ip ospf 100 area 0
ISP0(config-if)# interface serial 0/0/1
ISP0(config-if)# ip ospf 100 area 0

ISP0(config-if)# end

Router ISP 1

ISP1> enable
ISP1# configure terminal
ISP1(config)# router ospf 100
ISP1(config-router)# exit

ISP1(config)# interface serial 0/0/0
ISP1(config-if)# ip ospf 100 area 0
ISP1(config-if)# interface serial 0/0/1
ISP1(config-if)# ip ospf 100 area 0
ISP1(config-if)# end

Router ISP 2

ISP2> enable
ISP2# configure terminal
ISP2(config)# router ospf 100
ISP2(config-router)# exit

ISP2(config)# interface serial 0/0/0
ISP2(config-if)# ip ospf 100 area 0
ISP2(config-if)# interface serial 0/0/1
ISP2(config-if)# ip ospf 100 area 0
ISP2(config-if)# end

Tabelas de Routing

Usei o comando show ip route ospf para ver só as rotas geradas pelo OSPF.

Router R0

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.4 [110/128] via 10.0.0.1, 02:24:35, Serial0/0/0
O       10.0.0.8 [110/192] via 10.0.0.1, 02:24:21, Serial0/0/0
                 [110/192] via 10.0.0.13, 02:24:21, Serial0/0/1
O       10.0.0.16 [110/128] via 10.0.0.13, 02:24:21, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/129] via 10.0.0.13, 02:24:07, Serial0/0/1
O       172.16.2.0 [110/129] via 10.0.0.13, 02:24:07, Serial0/0/1

Router R1

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.0 [110/192] via 10.0.0.9, 01:56:39, Serial0/0/0
                 [110/192] via 10.0.0.17, 01:56:39, Serial0/0/1
O       10.0.0.4 [110/128] via 10.0.0.9, 02:26:30, Serial0/0/0
O       10.0.0.12 [110/128] via 10.0.0.17, 02:26:30, Serial0/0/1
O    192.168.0.0 [110/129] via 10.0.0.17, 02:26:30, Serial0/0/1
O    192.168.2.0 [110/129] via 10.0.0.17, 02:26:30, Serial0/0/1

Router ISP 0

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.8 [110/128] via 10.0.0.6, 02:25:01, Serial0/0/1
O       10.0.0.12 [110/128] via 10.0.0.2, 02:24:48, Serial0/0/0
O       10.0.0.16 [110/192] via 10.0.0.6, 02:24:48, Serial0/0/1
                  [110/192] via 10.0.0.2, 02:24:48, Serial0/0/0
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/129] via 10.0.0.6, 02:24:34, Serial0/0/1
O       172.16.2.0 [110/129] via 10.0.0.6, 02:24:34, Serial0/0/1
O    192.168.0.0 [110/65] via 10.0.0.2, 02:24:48, Serial0/0/0
O    192.168.2.0 [110/65] via 10.0.0.2, 02:24:48, Serial0/0/0

Router ISP 1

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.0 [110/128] via 10.0.0.5, 02:25:56, Serial0/0/0
O       10.0.0.12 [110/192] via 10.0.0.10, 02:25:43, Serial0/0/1
                  [110/192] via 10.0.0.5, 02:25:43, Serial0/0/0
O       10.0.0.16 [110/128] via 10.0.0.10, 02:25:43, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/65] via 10.0.0.10, 02:25:29, Serial0/0/1
O       172.16.2.0 [110/65] via 10.0.0.10, 02:25:29, Serial0/0/1
O    192.168.0.0 [110/129] via 10.0.0.5, 02:25:43, Serial0/0/0
O    192.168.2.0 [110/129] via 10.0.0.5, 02:25:43, Serial0/0/0

Router ISP 2

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.0 [110/128] via 10.0.0.14, 02:26:02, Serial0/0/0
O       10.0.0.4 [110/192] via 10.0.0.14, 01:56:01, Serial0/0/0
                 [110/192] via 10.0.0.18, 01:56:01, Serial0/0/1
O       10.0.0.8 [110/128] via 10.0.0.18, 02:26:02, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/65] via 10.0.0.18, 02:25:49, Serial0/0/1
O       172.16.2.0 [110/65] via 10.0.0.18, 02:25:49, Serial0/0/1
O    192.168.0.0 [110/65] via 10.0.0.14, 02:26:02, Serial0/0/0
O    192.168.2.0 [110/65] via 10.0.0.14, 02:26:02, Serial0/0/0

Comando clock rate

Para realizar analise realizei as alterações no router ISP 2.

ISP2(config)# interface serial 0/0/0
ISP2(config-if)# clock rate 1200
ISP2(config-if)# interface serial 0/0/1
ISP2(config-if)# clock rate 1200

Tabela de routing de R0 antes das alterações

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.4 [110/128] via 10.0.0.1, 02:24:35, Serial0/0/0
O       10.0.0.8 [110/192] via 10.0.0.1, 02:24:21, Serial0/0/0
                 [110/192] via 10.0.0.13, 02:24:21, Serial0/0/1
O       10.0.0.16 [110/128] via 10.0.0.13, 02:24:21, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/129] via 10.0.0.13, 02:24:07, Serial0/0/1
O       172.16.2.0 [110/129] via 10.0.0.13, 02:24:07, Serial0/0/1

Tabela de routing após a alteração

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.4 [110/128] via 10.0.0.1, 02:29:23, Serial0/0/0
O       10.0.0.8 [110/192] via 10.0.0.1, 02:29:09, Serial0/0/0
                 [110/192] via 10.0.0.13, 02:29:09, Serial0/0/1
O       10.0.0.16 [110/128] via 10.0.0.13, 02:29:09, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/129] via 10.0.0.13, 02:28:55, Serial0/0/1
O       172.16.2.0 [110/129] via 10.0.0.13, 02:28:55, Serial0/0/1

O clock rate altera a largura de banda, mas o OSPF não usa essa informação.

Alterar o valor de referencia

Para alterar o valor de referencia usamos o comando auto-cost reference-bandwidth "value"

Vou usar as tabelas de routing do router R0 para realizar a analise.

ISP2#enable
ISP2#configure
ISP2(config)#router ospf 100
ISP2(config-router)#auto-cost reference-bandwidth ?
  <1-4294967>  The reference bandwidth in terms of Mbits per second
ISP2(config-router)#auto-cost reference-bandwidth 4294967

Tabela de routing `reference-bandwidth 4294967``

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.4 [110/128] via 10.0.0.1, 02:38:27, Serial0/0/0
O       10.0.0.8 [110/192] via 10.0.0.1, 00:00:57, Serial0/0/0
O       10.0.0.16 [110/29266] via 10.0.0.13, 00:00:57, Serial0/0/1 - o custo desparou
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/193] via 10.0.0.1, 00:00:57, Serial0/0/0
O       172.16.2.0 [110/193] via 10.0.0.1, 00:00:57, Serial0/0/0

A rota para 172.16.0.0 tinha como via a rede 10.0.0.13, após as alterações a sua via passou a ser a rede 10.0.0.1.

A rota para 10.0.0.16 passou a ter um custo de 29266. 😱

ISP2(config-router)#auto-cost reference-bandwidth 100

Tabela de routing reference-bandwidth 100

     10.0.0.0/30 is subnetted, 5 subnets
O       10.0.0.4 [110/128] via 10.0.0.1, 02:41:29, Serial0/0/0
O       10.0.0.8 [110/192] via 10.0.0.1, 00:00:03, Serial0/0/0
                 [110/192] via 10.0.0.13, 00:00:03, Serial0/0/1
O       10.0.0.16 [110/128] via 10.0.0.13, 00:00:03, Serial0/0/1
     172.16.0.0/16 is variably subnetted, 2 subnets, 2 masks
O       172.16.0.0 [110/129] via 10.0.0.13, 00:00:03, Serial0/0/1
O       172.16.2.0 [110/129] via 10.0.0.13, 00:00:03, Serial0/0/1

De volta ao normal 😄