The next mode is interface mode and it displays the following, hostname, config-if
and brackets followed by hash or pound sign hostname(config-if)#
This mode allows you to change the configuration of an individual interface.
So for example you can change the IP address of the routers F0/0 interface
or you could disable the interface by shutting it down or enable the interface
by using the no shutdown command.
So various options are available in interface mode and commands available
will depend on the type of interface that you’re configuring.
A Ethernet interface would have a different options to a serial interface
which would be different in turn to a DSL interface or ATM interface.
So I can type int f0/0 which is interface FastEthernet 0/0 on this router
as you can see I’m abbreviating commands and it's good practice to do that.
As always remember you can hit the tab key which will complete a command for you.
So if I type exit to go back to privilege mode
and then type int and press tab notice the command is completed and now want to use
question mark I can see a list of available interface types.
So in the output I can see FastEthernet, loopback, serial interfaces and others.
I could then type f press tab which completes the command.
So fastethernet, press question mark and I can see the options
in this example I need to specify 0, so I can type 0?
And then told to enter forward slash and then i need to enter 0, so interface fastethernet 0/0
Notice how the Cisco IOS helps you complete commands.
It gives you relevant information about which options or parameters are available.
In the interface configuration mode I could use question mark.
Once again to see a list of options.
These options are specific to this mode and specifically this type of interface.
So I’m gonna type i?
And I can see various options including IP, IPV6, ISIS, and ISO-IGRP.
In this example I'm gonna specify ip ? and I can see options that pertain
or that are relevant to IP so I could choose IP address.
notice the options a? is new list of options
I can’t use ad cause there are multiple options
for that, so I have to specify add and now when I press tab
the command completes because that’s the only option available.
I could now specify an IP address for this interface.
notice I'm being prompted for the relevant information N
so if I go back again by pressing backspace and then use question mark of the IP address
I’m prompted to enter the IP address and subnet mask.
It prompts me for an IP address and after the IP address I'm prompted for the subnet mask.
If I press enter without completing a command, I'm told that the command is incomplete
I can use ctrl p or the up arrow key to display the previously entered command
and now I can enter the mask but if I enter the mask incorrectly
and press enter I'm told that the mask is invalid.
So press the up key, correct the mask and now when I press enter. the command is accepted.