Two switches are connected by an EtherChannel.
Which setting does not have to match on the connected ports in order to form an EtherChannel?
Click on the arrows to vote for the correct answer
A. B. C. D. E.C.
When creating an EtherChannel between two switches, certain settings must match to establish the link. However, not all settings have to match. The setting that does not have to match on the connected ports in order to form an EtherChannel is the spanning-tree PortFast settings (Answer B).
Here's a brief explanation of the settings:
A. Allowed VLAN list: For an EtherChannel to form, the allowed VLAN list must match on all ports in the channel. If the allowed VLAN list is not the same, the EtherChannel will not form. This is because frames belonging to different VLANs cannot be combined into the same EtherChannel.
B. Spanning-tree PortFast settings: PortFast is a Cisco proprietary feature that allows a switch port to transition from the blocking state to the forwarding state immediately. This feature is typically used on access ports that are connected to end hosts. Although it is not necessary for the PortFast settings to match on both ends of the link to form an EtherChannel, it is recommended to have the same PortFast settings on both ends to ensure consistent behavior.
C. DTP negotiation settings: Dynamic Trunking Protocol (DTP) is a Cisco proprietary protocol used to negotiate trunking between two switches. For an EtherChannel to form, the DTP negotiation settings must match on all ports in the channel. If one side is set to "desirable" and the other side is set to "auto" or "nonegotiate," the EtherChannel will not form.
D. Native VLAN: The native VLAN is the VLAN that is used for untagged frames on a trunk port. For an EtherChannel to form, the native VLAN must match on all ports in the channel. If the native VLAN is not the same, the EtherChannel will not form.
E. Spanning-tree port priorities for each VLAN: Spanning-tree port priorities are used to determine the root port and designated port on a switch. For an EtherChannel to form, the spanning-tree port priorities must match for all VLANs on all ports in the channel. If the spanning-tree port priorities are not the same, the EtherChannel will not form.
In summary, the only setting that does not have to match on the connected ports in order to form an EtherChannel is the spanning-tree PortFast settings (Answer B).