Keep These in Mind Before Setting up Cisco Switches

There are some important things to know before configuring a Cisco switch. It’s true that most switches today are pretty much plug and play. But this doesn’t always pan out. If you are going to make the transition, you need to figure some things out.


Know the Default VLAN


The default port is 1 so communication will be possible. If the VLAN switch is changed to another VLAN, port interaction won’t be possible.


Set up Interface VLAN 1


A switch requires an IP address if you want remote network management capabilities. A switch needs an IP address on an interface on every VLAN if the switch has many VLANs set up. Configuration is also necessary if you have to manage every switch. Even if every port is at VLAN 1, the IP address must still be set up on the VLAN 1 interface. This is a requirement for handling the switches.


Default Gateways are Necessary


Switches don’t really require a default gateway set up. But configuration is required if you need another subnet for switch communication. This will tell the switch how to obtain the LAN switch. The default gateway is set up in the following manner:

Switch(config)# ip default-gateway


Optimizing Ports


One of the things to know before configuring a Cisco switch is they have to be optimally set. You can instruct a switch that access devices are always on it. Just use these commands:


Switch(config)# interface FastEthernet0/48

Switch(config-if)# switchport mode access

Switch(config-if)# no shutdown

Switch(config-if)# spanning-tree portfast


Duplex and Speed Switch Ports


Duplex and speed are crucial on these ports. Switches are basically about hooking up a device to a local area network. If you have a lot of devices, issues with speed and duplex may come up. Legacy devices may not be compatible with switches. If you want to find out what speed and duplex a port is operating, use this command:


Switch# show interface gigabitEthernet 1/0/3

Switch# show interface gigabitEthernet 1/0/3


This will pop up:


Full-duplex, 100Mb/s, media type is 10/100/1000BaseTX

These commands will change the duplex or speed:


Switch(config)# interface gigabitEthernet 1/0/3

Switch(config-if)# speed 100

Switch(config-if)# duplex half


Notes on Starting the Switch


Be certain that the monitor terminal and switch are interactive. This is necessary for you to view the Cisco IOS command-line interface. The next step is the switch configuration. The next steps deal with the password configuration.


Port Security


This recalls the Ethernet MAC address joined to the switch port. It permits only that MAC address to interact with that port. The port will be disabled if another MAC address tries to interact with it. These switches are configured to transmit an SNMP trap notifying the port has been shut down. This setup can prevent devices from accessing the network. This is not without drawbacks of course. For instance, it can be inconvenient.


Under this setup, the port can only be unlocked by the network administrator. This can be very inconvenient if there are valid reasons to modify the devices.


Learning about the things to know before configuring a Cisco switch can be tedious. But it will help you in the long run. Even though these devices usually work without a hitch, being armed with knowledge is essential. The same thing goes for its security features. You can never be too careful in securing your network from viruses and other malicious software.


Charlie is a free lancer publisher of

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