Cisco me 3400 Guide De Logiciel

Spanning Tree Protocol is only supported on NNIs or ENIs on which it has been specifically 
enabled.

Do not configure a port to be a member of more than one EtherChannel group.

Do not configure an EtherChannel in both the PAgP and LACP modes. EtherChannel groups running 
PAgP and LACP can coexist on the same switch. Individual EtherChannel groups can run either 
PAgP or LACP, but they cannot interoperate.

PAgP and LACP are only available on NNIs and ENIs.

If the switch is running the metro base or metro access image, you can have only four NNIs on the 
switch at the same time; therefore, only four ports in an EtherChannel can support LACP and PAgP 
at the same time. If the switch is running the metro IP access image, there is no limit to the number 
of NNIs that can be configured on the switch.

Do not configure a Switched Port Analyzer (SPAN) destination port as part of an EtherChannel.

Do not configure a secure port as part of an EtherChannel or the reverse.

Do not configure a private-VLAN port as part of an EtherChannel.

Do not configure a port that is an active or a not-yet-active member of an EtherChannel as an 802.1x 
port. If you try to enable 802.1x on an EtherChannel port, an error message appears, and 802.1x is 
not enabled.

If EtherChannels are configured on switch interfaces, remove the EtherChannel configuration from 
the interfaces before globally enabling 802.1x on a switch by using the dot1x system-auth-control 
global configuration command. 

For Layer 2 EtherChannels:

Assign all ports in the EtherChannel to the same VLAN, or configure them as trunks. Ports with 
different native VLANs cannot form an EtherChannel.

If you configure an EtherChannel from trunk ports, verify that the trunking mode is the same on 
all the trunks. Inconsistent trunk modes on EtherChannel ports can have unexpected results.

An EtherChannel supports the same allowed range of VLANs on all the ports in a trunking 
Layer 2 EtherChannel. If the allowed range of VLANs is not the same, the ports do not form an 
EtherChannel even when PAgP is set to the auto or desirable mode.

NNIs or ENIs with different spanning-tree path costs can form an EtherChannel if they are 
otherwise compatibly configured. Setting different spanning-tree path costs does not, by itself, 
make ports incompatible for the formation of an EtherChannel.

For Layer 3 EtherChannels, assign the Layer 3 address to the port-channel logical interface, not to 
the physical ports in the channel.

You configure Layer 2 EtherChannels by assigning ports to a channel group with the channel-group 
interface configuration command. This command automatically creates the port-channel logical 
interface.