CCNA Complete Guide 2nd Edition.pdf - Cisco Learning Home

- Static Routing configuration on RT2:
RT2(config)#ip route 192.168.1.0 255.255.255.0 192.168.2.1
RT2(config)#ip route 192.168.5.0 255.255.255.0 192.168.4.2
RT2(config)#^Z
RT2#
- Static Routing configuration on RT3:
RT3(config)#ip route 192.168.1.0 255.255.255.0 192.168.4.1
RT3(config)#ip route 192.168.2.0 255.255.255.0 192.168.4.1
RT3(config)#ip route 192.168.3.0 255.255.255.0 192.168.4.1
RT3(config)#^Z
RT3#
- The values in the bracket [x/y] of the routes shown in the show ip route EXEC command
represent the administrative distance and metric respectively.
Default Routing Configuration
- Default routing is very useful in situations where learning all the more specific networks is
not desirable or not feasible due to limited system resources, eg: memory, processing power.
Packets destined to networks that are not in the routing table – unknown destination networks
will be directed to the default route. A default route is also known as the gateway of last resort.
- Default routing can only be used on stub networks – networks with only one entry and exit
point to all outside networks. RT1 and RT3 are considered in stub networks.
- Default routes can be configured by substituting the destination network and subnet mask with
wildcards (0.0.0.0) in the ip route static routing configuration command.
- Default Routing configuration on RT1:
RT1(config)#no ip route 192.168.3.0 255.255.255.0
RT1(config)#no ip route 192.168.4.0 255.255.255.0
RT1(config)#no ip route 192.168.5.0 255.255.255.0
RT1(config)#ip route 0.0.0.0 0.0.0.0 192.168.2.2
RT1(config)#^Z
RT1#
RT1#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
E1 - OSPF external type 1, E2 - OSPF external type 2, E – EGP
Gateway of last resort is 192.168.2.2 to network 0.0.0.0
C 192.168.1.0/24 is directly connected, FastEthernet1/0
C 192.168.2.0/24 is directly connected, Serial0/0
S* 0.0.0.0/0 [1/0] via 192.168.2.2
RT1#
- Notice the Gateway of last resort in the routing table. An asterisk (*) indicates a default route.
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