3.8 Configure, verify, and troubleshoot IPv4 and IPv6 static routing

This will be two parts. I will do the IPV4 part first.

Here is the topology used:

Screenshot_2018-04-02_18-09-33.png

3.8.a Default route

In order to get PC1 to be able to ping PC2 R1 needs to have a route to PC2’s subnet. This can be achieved using the default route:

R1(config)#ip route 0.0.0.0 0.0.0.0 172.16.0.2
R1(config)#^Z
R1#
*Apr 2 18:10:42.475: %SYS-5-CONFIG_I: Configured from console by console
R1#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 172.16.0.2 to network 0.0.0.0


172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, GigabitEthernet4/0
 10.0.0.0/24 is subnetted, 1 subnets
C 10.0.0.0 is directly connected, FastEthernet0/0
S* 0.0.0.0/0 [1/0] via 172.16.0.2
R1#

If R2 is configured the same PC1 will be able to ping PC2. PC1 and PC2 will also need a default route or gateway in the same subnet as their interface:

PC1> ip 10.0.0.2/24 10.0.0.1
Checking for duplicate address...
PC1 : 10.0.0.2 255.255.255.0 gateway 10.0.0.1

This configuration is not suitable for larger networks.

3.8.b Network router

We could configure router R1 and R2 to access each other with a static network route:

R1(config)#ip route 10.0.1.0 255.255.255.0 172.16.0.2

R2(config)#ip route 10.0.0.0 255.255.255.0 172.16.0.1

R2#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

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, GigabitEthernet4/0
 10.0.0.0/24 is subnetted, 2 subnets
S 10.0.0.0 [1/0] via 172.16.0.1
C 10.0.1.0 is directly connected, FastEthernet0/0
R2#

3.8.c Host route

We can also configure this route using a host route

R1(config)#ip route 10.0.1.1 255.255.255.255 172.16.0.2 

R1#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

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, GigabitEthernet4/0
 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks
S 10.0.1.1/32 [1/0] via 172.16.0.2
C 10.0.0.0/24 is directly connected, FastEthernet0/0
R1#

3.8.d Floating static

A route can be configured with a very high administrate distance (like 254):

R1(config)#ip route 10.0.1.0 255.255.255.0 172.16.0.2 254
R1(config)#^Z
R1#show i
*Apr 2 18:26:10.139: %SYS-5-CONFIG_I: Configured from console by console
R1#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

172.16.0.0/24 is subnetted, 1 subnets
C 172.16.0.0 is directly connected, GigabitEthernet4/0
 10.0.0.0/24 is subnetted, 2 subnets
C 10.0.0.0 is directly connected, FastEthernet0/0
S 10.0.1.0 [254/0] via 172.16.0.2
R1#

This way if all other routes with a lower administrative distance this backup route will be used.

 

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