Table of Contents
Cisco IOS primer
Written as a really basic intro to Cisco Ethernet Switches.
Cisco Ethernet switches are referred to as “Managed”, this means they can be programmed to control how they behave and also can be interrogated to determine the status and give any warnings about faults.
Example of an unmanaged switch intended for home or small office use. Limited number of ports.
Example of a Cisco Managed Switch, this has 24 copper ports and two fibre ports intended to link to other switches in the “core” of the network. Aimed at more commercial usage, but if you can find somewhere out of earshot (due to fan noise) for it to live, very reliable for home use too. Cheap off Ebay 2nd hand too. Don't use an enclosed cupboard as eventually they will get too hot without ventilation.
On a managed switch, you need to be able to access some sort of interface to control the switch, this is done via a serial port connection initially and then when the switch has an ip address allocated, it can be accessed over the network with either ssh or telnet.
In the picture, there ports bounded by blue are the console ports. There is a rj45 for serial and a USB which emulates a serial port. Using this avoids having to use an external usb to serial converter if your computer does not have a serial port. The four yellow ports at the bottom are for fibre modules (sfp) to connect to, the yellow rj45 at the top is for connecting to a management ethernet network.
Config
On first boot via the console connection (serial 9600 Baud, 8N1), you will be in “User Exec” level, so the commands here will be to view information only, to see sensitive information or change settings, you need to “Enable” “privileged Exec” level, the command for this is enable, shortened to en, with all commands ? will show possible completions and tab will complete as much of the command as it can, if something is ambiguous, it will complete as much as it can.
This link from Cisco gives a high level overview:- https://www.cisco.com/E-Learning/bulk/public/tac/cim/cib/using_cisco_ios_software/02_cisco_ios_hierarchy.htm
Examples
Console login with no passwords set
switch> en <------ User exec prompt ">" switch# <------ Privileged exec prompt "#" switch# exit <------ exit back to user exec switch>
Network login with passwords
user@x200:~$ ssh -l admin 192.168.1.2 <---- ssh for newer kit, telnet for older Password: 2960-1> 2960-1>en Password: 2960-1# 2960-1# exit 2960-1> exit Connection to 192.168.1.2 closed by remote host. Connection to 192.168.1.2 closed. user@x200:~$
Showing the current config, this is called the running config, the startup config is loaded from flash at boot time
2960-1#sh run <----------- Abbreviation of ''show running config'', tab will expand Building configuration... Current configuration: ! version 12.0 no service pad service timestamps debug uptime service timestamps log uptime no service password-encryption ! hostname c3548 ! ! interface FastEthernet0/1 description EGM port
Setting the device ipaddress and configuring an interface
2960-1# conf t <------- short for Configure Terminal 2960-1(config)#interface vlan 1 2960-1(config-if)#ip address 192.168.1.251 255.255.255.0 2960-1(config-if)# 2960-1(config-if)#exit 2960-1(config)#exit 2960-1# 00:07:57: %SYS-5-CONFIG_I: Configured from console by consolecopy runn 2960-1#copy running-config start <-------- tab expands this to startup-config 2960-1#copy running-config startup-config Destination filename [startup-config]? Building configuration... [OK] 2960-1# 2960-1# conf t <------- short for Configure Terminal 2960-1(config)#interface FastEthernet0/1 description Link to router exit 2960-1#
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