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#
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