Basic Router Configuration Review
Topology
A router creates a routing table to help it determine where to forward packets. But before diving into the details of the IP routing table, this topic reviews basic router configuration and verification tasks. You will also complete a Packet Tracer activity to refresh your skills.
The topology in the figure will be used for configuration and verification examples. It will also be used in the next topic to discuss the IP routing table.
Configuration Commands
The following examples show the full configuration for R1.
Router> enable
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# hostname R1
R1(config)# enable secret class
R1(config)# line console 0
R1(config-line)# logging synchronous
R1(config-line)# password cisco
R1(config-line)# login
R1(config-line)# exit
R1(config)# line vty 0 4
R1(config-line)# password cisco
R1(config-line)# login
R1(config-line)# transport input ssh telnet
R1(config-line)# exit
R1(config)# service password-encryption
R1(config)# banner motd #
Enter TEXT message. End with a new line and the #
***********************************************
WARNING: Unauthorized access is prohibited!
***********************************************
#
R1(config)# ipv6 unicast-routing
R1(config)# interface gigabitethernet 0/0/0
R1(config-if)# description Link to LAN 1
R1(config-if)# ip address 10.0.1.1 255.255.255.0
R1(config-if)# ipv6 address 2001:db8:acad:1::1/64
R1(config-if)# ipv6 address fe80::1:a link-local
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface gigabitethernet 0/0/1
R1(config-if)# description Link to LAN 2
R1(config-if)# ip address 10.0.2.1 255.255.255.0
R1(config-if)# ipv6 address 2001:db8:acad:2::1/64
R1(config-if)# ipv6 address fe80::1:b link-local
R1(config-if)# no shutdown
R1(config-if)# exit
R1(config)# interface serial 0/1/1
R1(config-if)# description Link to R2
R1(config-if)# ip address 10.0.3.1 255.255.255.0
R1(config-if)# ipv6 address 2001:db8:acad:3::1/64
R1(config-if)# ipv6 address fe80::1:c link-local
R1(config-if)# no shutdown
R1(config-if)# exit
R1# copy running-config startup-config
Destination filename [startup-config]?
Building configuration...
[OK]
R1#Verification Commands
Common verification commands include the following:
- show ip interface brief
- show running-config interface interface-type number
- show interfaces
- show ip interface
- show ip route
- ping
In each case, replace ip with ipv6 for the IPv6 version of the command. The figure shows the topology again for easy reference.
Filter Command Output
Another useful feature that improves user experience in the command-line interface (CLI) is filtering show output. Filtering commands can be used to display specific sections of output. To enable the filtering command, enter a pipe (|) character after the show command and then enter a filtering parameter and a filtering expression.
The filtering parameters that can be configured after the pipe include:
- section – This displays the entire section that starts with the filtering expression.
- include – This includes all output lines that match the filtering expression.
- exclude – This excludes all output lines that match the filtering expression.
- begin – This displays all the output lines from a certain point, starting with the line that matches the filtering expression.
Note: Output filters can be used in combination with any show command.
The figure again shows the topology for your convenience
These examples demonstrate some of the more common uses of filtering parameters.
R1# show running-config | section line vty
line vty 0 4
password 7 121A0C0411044C
login
transport input telnet ssh
R1#
R1# show ipv6 interface brief | include up
GigabitEthernet0/0/0 [up/up]
GigabitEthernet0/0/1 [up/up]
Serial0/1/1 [up/up]
R1#
R1# show ip interface brief | exclude unassigned
Interface IP-Address OK? Method Status Protocol
GigabitEthernet0/0/0 192.168.10.1 YES manual up up
GigabitEthernet0/0/1 192.168.11.1 YES manual up up
Serial0/1/1 209.165.200.225 YES manual up up
R1#
R1# show ip route | begin Gateway
Gateway of last resort is not set
192.168.10.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.10.0/24 is directly connected, GigabitEthernet0/0/0
L 192.168.10.1/32 is directly connected, GigabitEthernet0/0/0
192.168.11.0/24 is variably subnetted, 2 subnets, 2 masks
C 192.168.11.0/24 is directly connected, GigabitEthernet0/0/1
L 192.168.11.1/32 is directly connected, GigabitEthernet0/0/1
209.165.200.0/24 is variably subnetted, 2 subnets, 2 masks
C 209.165.200.224/30 is directly connected, Serial0/1/1
L 209.165.200.225/32 is directly connected, Serial0/1/1
R1#