Final answer:
Etherchannel: Auto / Desirable refers to the Port Aggregation Protocol (PAgP), a Cisco-proprietary protocol used for automatic EtherChannel configuration, with 'Auto' and 'Desirable' modes to passively or actively negotiate channel establishment.
Etherchannel: Auto/Desirable refers to: b) PAgP (Port Aggregation Protocol).
Step-by-step explanation:
The terms Etherchannel: Auto / Desirable refer to the Port Aggregation Protocol (PAgP), which is a Cisco-proprietary protocol used to facilitate the automatic creation of EtherChannel links. PAgP assists in the negotiation of establishing the link by exchanging packets between the ports of the involved switches.
The 'Auto' mode makes the port passively wait for PAgP packets from a partner device before forming an EtherChannel link, whereas the 'Desirable' mode actively sends PAgP packets to initiate the negotiation process for forming a link.
Etherchannel: Auto / Desirable refers to the Port Aggregation Protocol (PAgP), a Cisco-proprietary protocol used for automatic EtherChannel configuration, with 'Auto' and 'Desirable' modes to passively or actively negotiate channel establishment.