--- title: Basic Router Configuration tags: Cisco IOS, networking, manual, reference, router, technical --- <header> <h6>Basic Router Configuration</h6> > [toc] </header> --- # Initial Configuration Steps **The following configuration tasks should always be performed:** <ol class='step-list'> <li>Name the device to distinguish it from other routers, and configure passwords.</li> ```pug Router# configure terminal Router(config)# hostname R1 R1(config)# enable secret class R1(config)# line console 0 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 ``` <li>Enable password-encryption to encrypt plaintext passwords in the system config.</li> ``` R1(config)# service password-encryption R1(config)# ``` <li>Configure a banner to provide legal notification of unauthorized access.</li> ```pug R1(config)# banner motd $ Authorized Access Only! $ R1(config)# ``` <li>Save the changes on a router, as shown in the example.</li> ```pug R1# copy running-config startup-config ``` </ol> # Interface Configuration ```pug R1(config)# interface gigabitethernet 0/0/0 R1(config-if)# ip address 192.168.10.1 255.255.255.0 R1(config-if)# ipv6 address 2001:db8:acad:1::1/64 R1(config-if)# description Link to LAN 1 R1(config-if)# no shutdown R1(config-if)# exit R1(config)# interface gigabitethernet 0/0/1 R1(config-if)# ip address 192.168.11.1 255.255.255.0 R1(config-if)# ipv6 address 2001:db8:acad:2::1/64 R1(config-if)# description Link to LAN 2 R1(config-if)# no shutdown R1(config-if)# exit R1(config)# interface serial 0/0/0 R1(config-if)# ip address 209.165.200.225 255.255.255.252 R1(config-if)# ipv6 address 2001:db8:acad:3::225/64 R1(config-if)# description Link to R2 R1(config-if)# no shutdown R1(config-if)# exit R1(config)# ``` :::info A link-local address is automatically added to an interface whenever a global unicast address is assigned. An IPv6 network interface is required to have a link-local address, but *not* necessarily a global unicast address. ::: # IPv4 Loopback Interfaces The loopback interface is useful in testing and managing a Cisco IOS device because it ensures that at least one interface will always be available: the loopback interface is automatically placed in an “up” state, as long as the router is functioning. Enabling and assigning a loopback address is simple: ```pug R1(config)# interface loopback 0 R1(config-if)# ip address 10.0.0.1 255.255.255.0 R1(config-if)# exit R1(config)# ``` --- --- {%hackmd 7PGmjAHeTXak2VUM3iw5Wg %}