Switch Port Configuration

Cisco Operating Systems

Cisco offers two brands of network switches:

• Catalyst – Cisco’s flagship switching platform, with a large selection of models spanning 
access, distribution, and core layers.

• Nexus – high-end switches focused at datacenter environments.


Depending on the brand and model, Cisco supports one of three switch
operating systems:

• Catalyst OS (CatOS) - interface based on set commands, that is almost entirely deprecated. CatOS will not be covered in this guide.

• IOS – interface that is nearly identical to the Cisco router IOS, except for switching-specific commands.

• NX-OS – interface supported exclusively on Nexus brand switches.

Traditionally, network connections on switches have been referred to as ports, while on routers they are referred to as interfaces. However, in the Cisco IOS, switch ports are referred to as interfaces as well. 

Additionally, most Cisco switches are modular. Thus, configuration commands must reflect both the module and interface number, in the following format: module/interface 

Some catalyst switches support being stacked – essentially, multiple physical switches connected together to form one logical switch. Configuration commands must reflect the stack, module, and interface number, in the following format: stack/module/interface  

To enter interface configuration mode for the third Fast Ethernet interface off of the second module:

Switch(config)# interface FastEthernet 2/3

Switch(config-if)#

Note that most switches will number their modules and interfaces starting at 1, while most routers will number their modules/interfaces starting at 0.

The above command can be shortened, as long as the truncated command is
not ambiguous:

Switch(config)# interface fa 2/3

If the interface above was Gigabit Ethernet instead of Fast Ethernet:

Switch(config)# interface GigabitEthernet 2/3
Switch(config)# interface gi 2/3

Note: On Nexus switches using the NX-OS, the speed of an Ethernet interface is not used to identify it – all interfaces are simply Ethernet:


NexusSwitch(config)# interface Ethernet 2/3 

Multiple interfaces can be configured simultaneously:

Switch(config)# interface range gi2/3 , gi2/5 , gi2/7

Switch(config-if-range)#

OR

Switch(config)# interface range gi3/10 - 15 

Descriptions can be applied to an interface for documentation purposes:

Switch(config)# interface gi3/10
Switch(config-if)# description WEBSERVER

Spaces are allowed in a description:

Switch(config)# interface gi2/10

Switch(config-if)# description CHECK PRINTER IN PAYROLL 


For example, a Gigabit Ethernet interface is often backwards-compatible with original and Fast Ethernet, and is referred to as a 10/100/1000 interface.

To manually specify the speed of an interface:

 Switch(config)# interface gi3/10
 Switch(config-if)# speed 10
 Switch(config-if)# speed 100
 Switch(config-if)# speed 1000

The duplex of an interface can be manually specified as well:

 Switch(config)# interface gi3/10
 Switch(config-if)# duplex half

 Switch(config-if)# duplex full 

Ethernet also has the ability to auto-negotiate both the speed and duplex of an interface. Auto-negotiation will attempt to use the fastest speed available, and will attempt to use full-duplex if both devices support it.

Only one command is required to force an interface to auto-negotiate its speed and duplex:

 Switch(config)# interface gi3/10

 Switch(config-if)# speed auto 

To take an interface out of a shutdown state:

 Switch(config)# interface gi3/10
 Switch(config-if)# no shutdown

Intuitively, to place the interface into a shutdown state again:

 Switch(config)# interface gi3/10

 Switch(config-if)# shutdown

It is possible to shut or no shut multiple interface simultaneously, using the range command:

Switch(config)# interface range gi3/10 – 15

Switch(config-if-range)# no shut 

The show interface status command provides a high-level summary of all switch interfaces:  

To view which interfaces are currently in an errdisable state, including the reason for the errdisable condition: 

Ref:
https://www.routeralley.com/guides.html