OSPF

OSPF encuentra rutas mirando el estado del enlace. su métrica se basa en mirar el estado del ancho de banda de un enlace. Es un protocolo que utiliza Dijkstra para llegar a converger. La ventaja con respecto a RIP de este protocolo es que se reenvia la información de los routers sin modificar, llamados LSA(Line State Advertisment), aunque utiliza más recursos que RIP (memoria, CPU), tarda menos tiempo en converjer. Estos LSA envian el identificador del enlace, la ip el número de secuencia, y el coste.

No se envía toda la tabla de datos sin que se envían "hello", de esta manera conseguimos descongestionar la red.

Se trata de un protocolo jerárquico, donde tenemos que tener un área 0(backbone), donde se pueden poner más de 30 routers. los routers que estén en el límite del área estarán en el ABR (Area Border Route).

Soporta autenticación MD5 y de contraseña simple.

Soporta balanceo de trafico de igual coste (está predeterminado en 4 caminos)

Es un protocolo de classless, es decir, advierte la máscara.

Ejemplos de utilización de OSPF en un router:

RouterC(config)#router ospf 1

RouterC(config-router)#network 10.140.1.2 0.0.0.0 area 0

RouterC(config-router)#network 10.4.4.3 0.0.0.0 area 0

RouterC(config-router)#network 10.45.45.1 0.0.0.0 area 0

RouterC(config-router)#exit

RouterC(config)#int s0/0

RouterC(config-if)#ip ospf authentication

RouterC(config-if)#ip ospf authentication-key cisco (Esto se hace para que si ponemos un router nuevo de prueba, no anuncie nuevas rutas al sistema)

RouterC(config-if)#exit

RouterC(config)#exit

RouterC#sh

*Mar 11 03:41:46.466: %OSPF-5-ADJCHG: Process 1, Nbr 10.168.1.113 on Serial0/1 from LOADING to FULL, Loading Done

*Mar 11 03:41:46.938: %SYS-5-CONFIG_I: Configured from console by console protocols

Global values:

Internet Protocol routing is enabled

RouterC#sh ip protocols

Routing Protocol is "rip"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Sending updates every 30 seconds, next due in 22 seconds

Invalid after 180 seconds, hold down 180, flushed after 240

Redistributing: rip

Default version control: send version 2, receive version 2

Interface Send Recv Triggered RIP Key-chain

Ethernet0/0 2 2

Serial0/0 2 2

Serial0/1 2 2

Loopback0 2 2

Automatic network summarization is not in effect

Maximum path: 4

Routing for Networks:

3.0.0.0

10.0.0.0

Routing Information Sources:

Gateway Distance Last Update

10.45.45.2 120 00:00:17

10.140.3.1 120 00:00:11

Distance: (default is 120)

Routing Protocol is "ospf 1"

Outgoing update filter list for all interfaces is not set

Incoming update filter list for all interfaces is not set

Router ID 10.168.1.97

Number of areas in this router is 1. 1 normal 0 stub 0 nssa

Maximum path: 4

Routing for Networks:

10.4.4.3 0.0.0.0 area 0

10.45.45.1 0.0.0.0 area 0

10.140.1.2 0.0.0.0 area 0

Reference bandwidth unit is 100 mbps

Routing Information Sources:

Gateway Distance Last Update

10.140.4.1 110 00:01:21

10.168.1.113 110 00:01:21

10.168.1.65 110 00:01:21

10.168.1.81 110 00:01:21

Distance: (default is 110)

RouterC#show ip route

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 not set

10.0.0.0/8 is variably subnetted, 16 subnets, 3 masks

O 10.5.5.3/32 [110/65] via 10.45.45.2, 00:02:42, Serial0/1

C 10.45.45.0/24 is directly connected, Serial0/1

O 10.23.23.0/24 [110/973] via 10.45.45.2, 00:02:42, Serial0/1

R 10.5.5.0/24 [120/1] via 10.45.45.2, 00:00:01, Serial0/1

C 10.4.4.0/24 is directly connected, Ethernet0/0

O 10.3.3.0/24 [110/919] via 10.45.45.2, 00:02:42, Serial0/1

O 10.2.2.0/24 [110/983] via 10.45.45.2, 00:02:42, Serial0/1

O 10.1.1.0/24 [110/138] via 10.45.45.2, 00:02:43, Serial0/1

O 10.140.4.0/24 [110/128] via 10.45.45.2, 00:02:43, Serial0/1

O 10.140.2.0/24 [110/909] via 10.45.45.2, 00:02:43, Serial0/1

C 10.140.3.0/24 is directly connected, Serial0/0

O 10.140.1.0/24 [110/909] via 10.45.45.2, 00:02:43, Serial0/1

C 10.168.1.96/28 is directly connected, Loopback0

R 10.168.1.112/28 [120/1] via 10.45.45.2, 00:00:04, Serial0/1

R 10.168.1.64/28 [120/2] via 10.140.3.1, 00:00:01, Serial0/0

R 10.168.1.80/28 [120/2] via 10.140.3.1, 00:00:01, Serial0/0