Pruebas de redistribución de la ruta por defecto en OSPF

Fecha: 3 de noviembre del 2014 Clase: #899, módulo 8, CCNA 2 R&S

 

Escenario

 

Estudiando sobre OSPF en el aula, conversamos sobre que pasaría si dos routers publican la ruta

por defecto en OSPF: prevalece una sobre otra, o balancea carga ? la respuesta mas lógica es que

balanceara carga entre las dos, ya que coinciden máscaras, AD y el costo, pero en el Packet Tracer

la cosa se comportó diferente, a verificarlo con los equipos entonces…

 

 

Pruebas en Packet Tracer

 

Router_5(config)#ip route 0.0.0.0 0.0.0.0 null0 (creamos la primer ruta por defecto)

Router_5(config)#router ospf 1

Router_5(config-router)#default-information originate  (publicamos en OSPF)

Router_5(config-router)#^Z

Router_5#

 

Router_4#sh ip route (verificamos en el vecino)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is 192.168.72.5 to network 0.0.0.0

 

C    192.168.72.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 192.168.72.5, 00:00:57, FastEthernet0/0

Router_4#

 

Router_4#debug ip routing (para verificar los cambios en la tabla de enrutamiento)

IP routing debugging is on

Router_4#

 

Router_1#conf t (agregamos la segunda ruta por defecto al escenario)

Router_1(config)#ip route 0.0.0.0 0.0.0.0 null0

Router_1(config)#router ospf 1

Router_1(config-router)#default-information originate

Router_1(config-router)#^Z

Router_1#

 

Router_4#

RT: del 0.0.0.0 via 192.168.72.5, ospf metric [110/1]

RT: delete network route to 0.0.0.0 (elimina la ruta)

RT: NET-RED 0.0.0.0/0

RT: SET_LAST_RDB for 0.0.0.0/0

 

    NEW rdb: via 192.168.72.1

 

RT: add 0.0.0.0/0 via 192.168.72.1, ospf metric [110/1] (agrega la ruta)

RT: NET-RED 0.0.0.0/0

 

Router_4#sh ip route (verificamos y muestra la última agregada)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is 192.168.72.1 to network 0.0.0.0

 

C    192.168.72.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 192.168.72.1, 00:00:14, FastEthernet0/0

Router_4#

 

Pruebas con equipos reales

 

Router_5(config)#ip route 0.0.0.0 0.0.0.0 null0 (creamos la primer ruta por defecto)

Router_5(config)#router ospf 1

Router_5(config-router)#default-information originate  (publicamos en OSPF)

Router_5(config-router)#^Z

Router_5#

 

Router_4#sh ip route (verificamos en el vecino)

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is 192.168.72.5 to network 0.0.0.0

 

C    192.168.72.0/24 is directly connected, FastEthernet0/1

O*E2 0.0.0.0/0 [110/1] via 192.168.72.5, 00:02:15, FastEthernet0/1

Router_4#

 

Router_4#debug ip routing

IP routing debugging is on

Router_4#

 

Router_1#conf t (agregamos la segunda ruta por defecto al escenario)

Router_1(config)#ip route 0.0.0.0 0.0.0.0 null0

Router_1(config)#router ospf 1

Router_1(config-router)#default-information originate

Router_1(config-router)#^Z

Router_1#

 

Router_4#

*Nov  3 20:04:27.877: RT: NET-RED 0.0.0.0/0

*Nov  3 20:04:57.949: RT: add 0.0.0.0/0 via 192.168.72.1, ospf metric [110/1](agrega la ruta)

*Nov  3 20:04:57.949: RT: NET-RED 0.0.0.0/0

*Nov  3 20:04:57.949: RT: NET-RED 0.0.0.0/0

Router_4#

 

Router_4#sh ip route (verificamos y balancea carga)

Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2

       i - IS-IS, su - IS-IS summary, L1 - IS-IS level-1, L2 - IS-IS level-2

       ia - IS-IS inter area, * - candidate default, U - per-user static route

       o - ODR, P - periodic downloaded static route

 

Gateway of last resort is 192.168.72.5 to network 0.0.0.0

 

C    192.168.72.0/24 is directly connected, FastEthernet0/1

O*E2 0.0.0.0/0 [110/1] via 192.168.72.5, 00:03:16, FastEthernet0/1

                          [110/1] via 192.168.72.1, 00:00:13, FastEthernet0/1

Router_4#

 

Ya que estamos, verificamos que pasaría si Router_5 tiene dos rutas por defecto y las

publica a ambas en el OSPF. Esta prueba se realizó con los equipos y con PT con resultados

similares, el OSPF publica unicamente el gateway para alcanzar la ruta por defecto y no la

cantidad de rutas que posee.

 

 

 

 

Router_1(config)#no ip route 0.0.0.0 0.0.0.0 null0 (eliminamos la ruta null anterior)

 

Router_5(config)#no ip route 0.0.0.0 0.0.0.0 null0 (eliminamos la ruta null anterior)

Router_5(config)#int loop 0

Router_5(config-if)#ip add 190.0.0.1 255.255.255.255

Router_5(config-if)#exit

Router_5(config)#int loop 1

Router_5(config-if)#ip add 200.0.0.1 255.255.255.255

Router_5(config-if)#exit

Router_5(config)#ip route 0.0.0.0 0.0.0.0 loop 0

Router_5(config)#ip route 0.0.0.0 0.0.0.0 loop 1

Router_5(config)#^Z

Router_5#

 

Router_4#debug ip routing (verificamos desde el vecino)

IP routing debugging is on

Router_4#RT: SET_LAST_RDB for 0.0.0.0/0

 

    NEW rdb: via 192.168.72.5

 

RT: add 0.0.0.0/0 via 192.168.72.5, ospf metric [110/1]

 

RT: NET-RED 0.0.0.0/0

 

Router_4#

 

 

Router_5#sh ip route (verificamos)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is 0.0.0.0 to network 0.0.0.0

 

     190.0.0.0/32 is subnetted, 1 subnets

C       190.0.0.1 is directly connected, Loopback0

C    192.168.72.0/24 is directly connected, FastEthernet0/0

     200.0.0.0/32 is subnetted, 1 subnets

C       200.0.0.1 is directly connected, Loopback1

S*   0.0.0.0/0 is directly connected, Loopback0

                       is directly connected, Loopback1

Router_5#

 

Router_4#sh ip route (verificamos desde el vecino)

Codes: C - connected, S - static, I - IGRP, R - RIP, M - mobile, B - BGP

       D - EIGRP, EX - EIGRP external, O - OSPF, IA - OSPF inter area

       N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2

       E1 - OSPF external type 1, E2 - OSPF external type 2, E - EGP

       i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area

       * - candidate default, U - per-user static route, o - ODR

       P - periodic downloaded static route

 

Gateway of last resort is 192.168.72.5 to network 0.0.0.0

 

C    192.168.72.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 192.168.72.5, 00:00:45, FastEthernet0/0

Router_4#

 

(2014) Reading about OSPF a rainy Sunday afternoon

Rosario, Argentina