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Configuring Interfaces
Configuring Ethernet Interfaces
Configuring the Port Type
By default, all the 10/100 ports on the switch are configured as UNIs, and the SFP module ports are configured as NNIs.
You use the port-type interface configuration command to change the port types. An ENI has the same characteristics
as a UNI, but it can be configured to support CDP, STP, LLDP, and Etherchannel LACP and PAgP.
When a port is changed from an NNI to a UNI or ENI, it inherits the configuration of the assigned VLAN, either in isolated
or community mode.
When you change a port from NNI to UNI or ENI or the reverse, any features exclusive to the port type revert to the default
configuration. For Layer 2 protocols, such as STP, CDP, and LLDP, the default for UNIs and ENIs is disabled (although they
can be enabled on ENIs) and the default for NNIs is enabled.
Note: By default, the switch sends keepalive messages on UNI s and ENIs and does not send keepalive messages on
NNIs. Changing the port type from UNI or ENI to NNI or from NNI to UNI or ENI has no effect on the keepalive status. You
can change the keepalive state from the default setting by entering the [no] keepalive interface configuration command.
If you enter the keepalive command with no arguments, keepalive packets are sent with the default time interval (10
seconds) and number of retries (5). Entering the no keepalive command disables keepalive packets on the interface.
Beginning in privileged EXEC mode, follow these steps to configure the port type on an interface:
Table 7 Default Ethernet Configuration for UNIs and ENIs
Feature Default Setting
Operating mode Layer 2 or switching mode (switchport command).
Allowed VLAN range VLANs 1– 4094.
Default VLAN (for access ports) VLAN 1 (Layer 2 interfaces only).
Native VLAN (for 802.1Q trunks) VLAN 1 (Layer 2 interfaces only).
VLAN trunking Switchport mode access (Layer 2 interfaces only).
Dynamic VLAN Enabled.
Port enable state Disabled when no configuration file exists.
Port description None defined.
Speed Autonegotiate.
Duplex mode Autonegotiate.
802.3x flow control Flow control is set to receive: off. It is always off for sent packets.
EtherChannel Disabled on all Ethernet ports. See Configuring EtherChannels, page 1027
Port blocking (unknown multicast and
unknown unicast traffic)
Disabled (not blocked) (only Layer 2 interfaces).
Broadcast, multicast, and unicast storm
control
Disabled.
Port security Disabled (only Layer 2 interfaces).
Auto-MDIX Enabled.
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