Reference Guide
A trunk interface carries VLAN trac that is tagged using 802.1q encapsulation. If an access interface receives a packet with an 802.1q tag
in the header that is dierent from the access VLAN ID, it drops the packet.
By default, a trunk interface carries only untagged trac on the access VLAN — you must manually congure other VLANs for tagged
trac.
1 Select one of the two available options:
• Congure L2 trunking in INTERFACE mode and the tagged VLAN trac that the port can transmit. By default, a trunk port is not
added to any tagged VLAN. You must create a VLAN before you can assign the interface to it.
switchport mode trunk
switchport trunk allowed vlan vlan-id-list
• Recongure the access VLAN assigned to a L2 access or trunk port in INTERFACE mode.
switchport access vlan vlan-id
2 Enable the interface for L2 trac transmission in INTERFACE mode.
no shutdown
3 Save the conguration.
do commit
L2 interface conguration
OS10(config)# interface ethernet 1/1/7
OS10(conf-if-eth1/1/7)# switchport mode trunk
OS10(conf-if-eth1/1/7)# switchport trunk allowed vlan 5,10
OS10(conf-if-eth1/1/7)# no shutdown
OS10(conf-if-eth1/1/7)# do commit
L3 mode conguration
Ethernet and port-channel interfaces are in L2 access mode by default. When you remove L2 mode and assign an IP address to an
Ethernet port interface, you place the port in L3 mode.
Congure one primary IP address in L3 mode. You can congure up to 255 secondary IP addresses on an interface. At least one interface in
the system must be in L3 mode before you congure or enter a L3 protocol mode, such as OSPF.
1 Remove a port from L2 switching in INTERFACE mode.
no switchport
2 Congure L3 routing in INTERFACE mode. Add the keyword secondary to congure backup IP addresses.
ip address address [secondary]
3 Enable the interface for L3 trac transmission in INTERFACE mode.
no shutdown
4 Save the conguration.
do commit
L3 interface conguration
OS10(config)# interface ethernet 1/1/9
OS10(conf-if-eth1/1/9)# no switchport
OS10(conf-if-eth1/1/9)# ip address 10.10.1.92/24
OS10(conf-if-eth1/1/9)# no shutdown
OS10(conf-if-eth1/1/9)# do commit
View L3 conguration error
OS10(config)# interface ethernet 1/1/1
OS10(conf-if-eth1/1/1)# ip address 1.1.1.1/24
OS10(conf-if-eth1/1/1)# do commit
% Error: remove Layer 2 configuration before assigning an IP
Interfaces
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