Ruta por defecto en ambientes multiprotocolo

                Fecha: 24 de junio 2014 Clase: Exploration2 (CCNA 2)

 

Escenario

 

En este escenario en ambos routers de la sucursal se utilizan los dos protocolos de enrutamiento con la red

local como parámetro en común, esto permite que los PC de la red no deban cambiar los default gateway

en caso de que alguno de los enlaces falle.

Esto permite que se observe un detalle, OSPF le “gana” a EIGRP en la utilización de la ruta por defecto debido

a que cuando redistribuye la ruta estática, no le cambia la distancia administrativa (110), EIGRP sí (90 x 170).

 

Este escenario se realizó en PT y se verificó con equipos reales.

 

                PC>tracert 190.0.0.1

 

Tracing route to 190.0.0.1 over a maximum of 30 hops:

 

  1   0 ms      0 ms      0 ms      192.168.2.1 (GW_OSPF)

  2   15 ms     1 ms      1 ms      10.0.0.2 (OSPF)

  3   16 ms     31 ms     47 ms     10.0.0.14 (Rosario, pero el paquete vuelve por enlace EIGRP)

  4   *         16 ms     32 ms     190.0.0.1 (Internet)

 

Trace complete.

 

PC>

 

GW_OSPF#sh ip route (gateway del PC)

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 10.0.0.2 to network 0.0.0.0

 

     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks

D       10.0.0.0/8 [90/2172416] via 192.168.2.2, 00:11:52, FastEthernet0/0

C       10.0.0.0/30 is directly connected, Serial0/0/0

O       10.0.0.8/30 [110/128] via 10.0.0.2, 00:06:36, Serial0/0/0

D    192.168.1.0/24 [90/2686976] via 192.168.2.2, 00:09:50, FastEthernet0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 10.0.0.2, 00:06:36, Serial0/0/0 (la ruta por defecto se aprende vía OSPF por la menor AD)

GW_OSPF#

 

GW_EIGRP#sh ip route

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 192.168.2.1 to network 0.0.0.0

 

     10.0.0.0/8 is variably subnetted, 5 subnets, 2 masks

D       10.0.0.0/8 is a summary, 00:13:19, Null0

O       10.0.0.0/30 [110/65] via 192.168.2.1, 00:12:20, FastEthernet0/0

C       10.0.0.4/30 is directly connected, Serial0/0/1

O       10.0.0.8/30 [110/129] via 192.168.2.1, 00:08:01, FastEthernet0/0

D       10.0.0.12/30 [90/2681856] via 10.0.0.6, 00:11:51, Serial0/0/1

D    192.168.1.0/24 [90/2684416] via 10.0.0.6, 00:11:15, Serial0/0/1

C    192.168.2.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 192.168.2.1, 00:08:01, FastEthernet0/0 (la ruta por defecto se aprende vía OSPF por la menor AD)

GW_EIGRP#

 

Se cae el enlace OSPF

 

GW_OSPF#

 

%LINK-5-CHANGED: Interface Serial0/0/0, changed state to down

%LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0, changed state to down

00:27:08: %OSPF-5-ADJCHG: Process 1, Nbr 10.0.0.9 on Serial0/0/0 from FULL to DOWN, Neighbor Down: Interface down or detached

 

GW_OSPF#sh ip route

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 192.168.2.2 to network 0.0.0.0

 

D    10.0.0.0/8 [90/2172416] via 192.168.2.2, 00:14:33, FastEthernet0/0

D    192.168.1.0/24 [90/2686976] via 192.168.2.2, 00:12:30, FastEthernet0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/0

D*EX 0.0.0.0/0 [170/2710016] via 192.168.2.2, 00:12:18, FastEthernet0/0 (la ruta por defecto  ahora es vía EIGRP)

GW_OSPF#

 

PC>tracert 190.0.0.1

 

Tracing route to 190.0.0.1 over a maximum of 30 hops:

 

  1   0 ms      0 ms      0 ms      192.168.2.1

  2   *         0 ms      0 ms      192.168.2.2

  3   15 ms     15 ms     31 ms     10.0.0.6

  4   16 ms     16 ms     63 ms     10.0.0.14

  5   *         16 ms     16 ms     190.0.0.1

 

Trace complete.

 

PC>

 

Solución para que en la ruta por defecto tenga prioridad EIGRP sobre OSPF

 

Esto debe implementarse en todos los routers que trabajen con EIGRP.

 

Rosario(config)#router eigrp 10

Rosario(config-router)#distance eigrp ?

  <1-255>  Distance for internal routes

Rosario(config-router)#distance eigrp 90 ?

  <1-255>  Distance for external routes

Rosario(config-router)#distance eigrp 90 100 (se modifica menor a 110 del OSPF)

Rosario(config-router)#^Z

Rosario#

 

Verificación

 

GW_EIGRP#sh ip route

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 10.0.0.6 to network 0.0.0.0

 

     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks

D       10.0.0.0/8 is a summary, 00:01:13, Null0

C       10.0.0.4/30 is directly connected, Serial0/0/1

D       10.0.0.12/30 [90/2681856] via 10.0.0.6, 00:00:13, Serial0/0/1

D    192.168.1.0/24 [90/2684416] via 10.0.0.6, 00:00:13, Serial0/0/1

C    192.168.2.0/24 is directly connected, FastEthernet0/0

D*EX 0.0.0.0/0 [100/2707456] via 10.0.0.6, 00:00:13, Serial0/0/1 (ver AD de 100)

GW_EIGRP#

 

GW_OSPF#sh ip route

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 192.168.2.2 to network 0.0.0.0

 

     10.0.0.0/8 is variably subnetted, 3 subnets, 2 masks

D       10.0.0.0/8 [90/2172416] via 192.168.2.2, 00:00:03, FastEthernet0/0

C       10.0.0.0/30 is directly connected, Serial0/0/0

O       10.0.0.8/30 [110/128] via 10.0.0.2, 00:04:50, Serial0/0/0

D    192.168.1.0/24 [90/2686976] via 192.168.2.2, 00:00:03, FastEthernet0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/0

D*EX 0.0.0.0/0 [100/2710016] via 192.168.2.2, 00:00:03, FastEthernet0/0 (en lugar de OSPF tipo 2)

GW_OSPF#

 

Cae el tramo EIGRP

 

GW_OSPF#debug ip routing

IP routing debugging is on

GW_OSPF#

 

RT: del 0.0.0.0 via 192.168.2.2, eigrp metric [100/2710016] (borra la ruta EIGRP de la tabla)

RT: delete network route to 0.0.0.0

RT: NET-RED 0.0.0.0/0

RT: SET_LAST_RDB for 0.0.0.0/0

 

    NEW rdb: via 10.0.0.2

 

RT: add 0.0.0.0/0 via 10.0.0.2, ospf metric [110/1] (agrega la ruta OSPF en la tabla)

RT: NET-RED 0.0.0.0/0

 

GW_OSPF#sh ip route

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 10.0.0.2 to network 0.0.0.0

 

     10.0.0.0/30 is subnetted, 2 subnets

C       10.0.0.0 is directly connected, Serial0/0/0

O       10.0.0.8 [110/128] via 10.0.0.2, 00:06:33, Serial0/0/0

O    192.168.1.0/24 [110/129] via 10.0.0.2, 00:06:33, Serial0/0/0

C    192.168.2.0/24 is directly connected, FastEthernet0/0

O*E2 0.0.0.0/0 [110/1] via 10.0.0.2, 00:06:33, Serial0/0/0 (ahora la ruta por defecto es OSPF)

GW_OSPF#

 

 

Fuente: http://www.cisco.com/c/en/us/td/docs/ios/12_2/iproute/command/reference/fiprrp_r/1rfeigrp.html#wp1017590

 

Post data: Solución para que los routers tengan sólo un protocolo de enrutamiento

 

Se utiliza el protocolo HSRP (Hot Santdby Routing Protocol) para generar una IP y MAC virtuales,

esta se utiliza como el default gateway de las PC. Esto también podría evitar el ICMP redirect.

 

El tema del HSRP es mas complejo, aquí se detalla sólo para este uso.

 

GW_OSPF(config)#no router eigrp 10 (se elimina el segundo protocolo)

GW_OSPF(config)#interface FastEthernet0/0

GW_OSPF(config-if)#ip address 192.168.2.3 255.255.255.0 (se reemplaza la IP ya que la configurada la utilizará la IP virtual)

GW_OSPF(config-if)#standby ip 192.168.2.1 (IP virtual a utilizarse como gateway de las PC)

GW_OSPF(config-if)#end

GW_OSPF#

 

GW_EIGRP(config)#no router ospf 1 (se elimina el segundo protocolo)

GW_EIGRP(config)#interface FastEthernet0/0

GW_EIGRP(config-if)#standby ip 192.168.2.1 (IP virtual a utilizarse como gateway de las PC)

GW_EIGRP(config-if)#^Z

GW_EIGRP#

 

%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 0 state Speak -> Standby

%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 0 state Standby -> Active

 

PC>ipconfig

 

FastEthernet0 Connection:(default port)

Link-local IPv6 Address.........: FE80::2D0:58FF:FEC3:7BEC

IP Address......................: 192.168.2.10

Subnet Mask.....................: 255.255.255.0

Default Gateway.................: 192.168.2.1

 

PC>tracert 190.0.0.1

 

Tracing route to 190.0.0.1 over a maximum of 30 hops:

 

  1   16 ms     0 ms      0 ms      192.168.2.2 (router con HSRP activo)

  2   31 ms     31 ms     17 ms     10.0.0.6  (EIGRP)

  3   31 ms     31 ms     32 ms     10.0.0.14 (Rosario)

  4   16 ms     16 ms     16 ms     190.0.0.1 (Internet)

 

Trace complete.

 

PC> arp -a

  Internet Address      Physical Address      Type

  192.168.2.1           0000.0c9f.f000        dynamic (IP y MAC virtuales)

  192.168.2.2           0060.3e12.0365        dynamic (GW_EIGRP)

  192.168.2.3           0090.2100.3d01        dynamic (GW_OSPF)

 

PC>

 

 

 

PC>ipconfig

 

FastEthernet0 Connection:(default port)

Link-local IPv6 Address.........: FE80::2D0:58FF:FEC3:7BEC

IP Address......................: 192.168.2.10

Subnet Mask.....................: 255.255.255.0

Default Gateway.................: 192.168.2.1

 

PC>tracert 190.0.0.1

 

Tracing route to 190.0.0.1 over a maximum of 30 hops:

 

  1   0 ms      0 ms      0 ms      192.168.2.3 (router con HSRP que pasa de standby a activo)

  2   0 ms      0 ms      16 ms     10.0.0.2 (OSPF)

  3   31 ms     0 ms      31 ms     10.0.0.10 (Rosario)

  4   15 ms     31 ms     32 ms     190.0.0.1(Internet)

 

Trace complete.

 

PC>

 

Verificación del otro gateway (para no quedarnos con la duda de que no ande…)

 

GW_EIGRP>

%DUAL-5-NBRCHANGE: IP-EIGRP 10: Neighbor 192.168.2.3 (FastEthernet0/0) is down: holding time expired

%HSRP-6-STATECHANGE: FastEthernet0/0 Grp 0 state Standby -> Active

GW_EIGRP>

 

PC>ipconfig

 

FastEthernet0 Connection:(default port)

Link-local IPv6 Address.........: FE80::2D0:58FF:FEC3:7BEC

IP Address......................: 192.168.2.10

Subnet Mask.....................: 255.255.255.0

Default Gateway.................: 192.168.2.1 (IP virtual)

 

PC>tracert 190.0.0.1

 

Tracing route to 190.0.0.1 over a maximum of 30 hops:

 

  1   16 ms     0 ms      0 ms      192.168.2.2 (GW_EIGRP)

  2   15 ms     15 ms     15 ms     10.0.0.6 (EIGRP)

  3   15 ms     31 ms     47 ms     10.0.0.14 (Rosario)

  4   15 ms     15 ms     31 ms     190.0.0.1 (Internet)

 

Trace complete.

 

PC>

 

(2014)Forwarding  to the route 66

Rosario, Argentina