Basic Router Configuration - MODULO 10

Question 1

Basic Router Configuration Steps
The following tasks should be completed when configuring initial settings on a router.

Answer 1

1. Configure the device name.
   Router(config)# hostname hostname
2. Secure privileged EXEC mode.
   Router(config)# enable secret password
3. Secure user EXEC mode.
   Router(config)# line console 0
   Router(config-line)# password password
   Router(config-line)# login
4. Secure remote Telnet / SSH access.
   Router(config-line)# line vty 0 4
   Router(config-line)# password password
   Router(config-line)# login
   Router(config-line)# transport input {ssh | telnet}
5. Secure all passwords in the config file.
   Router(config-line)# exit
   Router(config)# service password-encryption
6. Provide legal notification.
   Router(config)# banner motd delimiter message delimiter
7. Save the configuration.
   Router(config)# end
   Router# copy running-config startup-config

Question 2

All router access should be secured.

Answer 2

Privileged EXEC mode provides the user with
complete access to the device and its configuration. Therefore, it is the most important
mode to secure.

Question 3

Configure Router Interfaces

Answer 3

At this point, your routers have their basic configurations.
The next step is to configure their interfaces.
This is because routers are not reachable by end devices until the interfaces are
configured.
There are many different types of interfaces available on Cisco routers. For example, the
Cisco ISR 4321 router is equipped with two Gigabit Ethernet interfaces:
* GigabitEthernet 0/0/0 (G0/0/0)
* GigabitEthernet 0/0/1 (G0/0/1)

Question 4

Verify Interface Configuration

Answer 4

There are several commands that can be used to verify interface configuration. The most
useful of these is the show ip interface brief and show ipv6 interface brief commands,
as shown in the example.

Question 5

Default Gateway on a Host

Answer 5

If your local network has only one router, it will be the gateway router and all hosts and
switches on your network must be configured with this information.
If your local network has multiple routers, you must select one of them to be the default
gateway router.
This topic explains how to configure the default gateway on hosts and switches.
For an end device to communicate over the network, it must be configured with the correct
IP address information, including the default gateway address.
The default gateway is only used when the host wants to send a packet to a device on
another network.
The default gateway address is generally the router interface address attached to the local
network of the host.
The IP address of the host device and the router interface address must be in the same
network.
For example, assume an IPv4 network topology consisting of a router interconnecting two
separate LANs.
G0/0/0 is connected to network 192.168.10.0, while G0/0/1 is connected to network
192.168.11.0.
Each host device is configured with the appropriate default gateway address.
In this example, if PC1 sends a packet to PC2, then the default gateway is not used.
Instead, PC1 addresses the packet with the IPv4 address of PC2 and forwards the
packet directly to PC2 through the switch.

Question 6

Default Gateway on a Switch

Answer 6

A switch that interconnects client computers is typically a Layer 2 device.
As such, a Layer 2 switch does not require an IP address to function properly.
However, an IP configuration can be configured on a switch to give an administrator remote
access to the switch.
To connect to and manage a switch over a local IP network, it must have a switch virtual
interface (SVI) configured.
The SVI is configured with an IPv4 address and subnet mask on the local LAN.
The switch must also have a default gateway address configured to remotely manage the
switch from another network.
The default gateway address is typically configured on all devices that will communicate
beyond their local network.
To configure an IPv4 default gateway on a switch, use the ip default-gateway ip
address global configuration command. The ip-address that is configured is the IPv4
address of the local router interface connected to the switch.
The figure shows an administrator establishing a remote connection to switch S1 on
another network.

Question 7

Configure Initial Router Settings

Answer 7

The following tasks should be completed when configuring initial settings on a router.
1. Configure the device name.
2. Secure privileged EXEC mode.
3. Secure user EXEC mode.
4. Secure remote Telnet / SSH access.
5. Secure all passwords in the config file.
6. Provide legal notification.
7. Save the configuration.

Question 8

Configure Interfaces

Answer 8

For routers to be reachable, the router interfaces must be configured.
The Cisco ISR 4321 router is equipped with two Gigabit Ethernet interfaces:
GigabitEthernet 0/0/0 (G0/0/0) and GigabitEthernet 0/0/1 (G0/0/1).
The tasks to configure a router interface are very similar to a management SVI on a
switch.
Using the no shutdown command activates the interface.
The interface must also be connected to another device, such as a switch or a router, for
the physical layer to be active.
There are several commands that can be used to verify interface configuration including
the show ip interface brief and show ipv6 interface brief, the show ip route and show
ipv6 route, as well as show interfaces, show ip interface and show ipv6 interface.

Question 9

Configure the Default Gateway

Answer 9

For an end device to communicate over the network, it must be configured with the correct
IP address information, including the default gateway address.
The default gateway address is generally the router interface address for the router that is
attached to the local network of the host.
The IP address of the host device and the router interface address must be in the same
network.
To connect to and manage a switch over a local IP network, it must have a switch virtual
interface (SVI) configured.
The SVI is configured with an IPv4 address and subnet mask on the local LAN.
The switch must also have a default gateway address configured to remotely manage the
switch from another network.
To configure an IPv4 default gateway on a switch, use the ip default-gateway ip
address global configuration command.
Use the IPv4 address of the local router interface that is connected to the switch.