Cisco Certified Network Professional Practice Test 2026 – Your All-in-One Guide to Exam Success!

In Port Aggregation Protocol (PAgP) configurations, the "On" mode indicates that the EtherChannel is configured to operate without any negotiation. This means that the interfaces participating in the EtherChannel are forced into an aggregated state, and will not send or receive PAgP packets to negotiate the formation of the channel.

When an EtherChannel is set to "On", it effectively bypasses the PAgP negotiation process entirely, which can lead to an EtherChannel formation without ensuring that the configuration on both ends of the link matches. This decision to omit the negotiation can be beneficial in situations where the network administrator is certain that the settings (such as speed, duplex, and trunking configurations) on both ends are identical and that they want a specific setup to be enforced immediately without the overhead of negotiation.

In contrast, other modes such as "Auto" and "Desirable" would involve the exchange of PAgP packets to agree on channel capabilities, enhancing compatibility and reducing the chances of errors related to mismatched configurations.