What is a Access port on a Cisco switch.
An access port is a nontrunking, untagged single VLAN Layer 2 interface in its default configuration.
By default, a Cisco switchport is set to "dynamic desireable", meaning that if you connect a device that supports trunking, then the switchport will negotiate a trunk. By setting the port as access port it will ignore all attempts to negotiate link type. As a best practice and from security perspective it is advised to define the switch port mode.
An access port can have only one VLAN configured on the interface. It can carry traffic for only one VLAN. By default the access port is configured in VLAN 1. If an access port receives a packet with an 802.1Q tag in the header other than the access VLAN value, that port drops the packet.
Access ports are used to connect an end device such as a Pc/Laptop, Server or a printer.
Configuring a LAN Interface as an Ethernet Access Port
From the interface mode give the command "switchport mode access" to force the port as access port.
switch# configure terminal
switch(config)# interface ethernet 0/5
switch(config-if)# switchport mode access
switch(config-if)# switchport access vlan 5
switch(config)# interface ethernet 0/5
switch(config-if)# switchport mode access
switch(config-if)# switchport access vlan 5