Detect LACP Mode for Configuring EtherChannel Bundles

A

The LACP is Link Aggregation Control Protocol. LACP is an open protocol, published under the 802.3ad.

The modes of LACP are active, passive or on. The side configured as passive will waiting the other side that should an Active for the Etherchannel to be established.

PAgP is Port-Aggregation Protocol. It is Cisco proprietary protocol. The mode are On, Desirable or Auto. Desirable " Auto will establish an EtherChannel.

An example of how to configure an Etherchannel:

SwitchFormula1>enable -

SwitchFormula1#configure terminal

SwitchFormula1(config)# interface range f0/5 -14

SwitchFormula1(config-if-range)# channel-group 13 mode ?

active Enable LACP unconditionally

auto Enable PAgP only if a PAgP device is detected

desirable Enable PAgP unconditionally

on Enable Etherchannel only

passive Enable LACP only if a LACP device is detected

When configuring an EtherChannel bundle, there are various modes that can be used for Link Aggregation Control Protocol (LACP) negotiation. LACP is a protocol used to automatically bundle multiple physical links into a single logical link to provide higher bandwidth and redundancy.

The different modes available for LACP negotiation are:

A. Passive: In passive mode, the port does not initiate the LACP negotiation process. It will only respond to LACP messages received from the other end of the link. If the other end of the link is set to active mode, the port will still form an EtherChannel bundle.

B. Desirable: In desirable mode, the port actively initiates the LACP negotiation process and sends LACP messages to the other end of the link. If the other end of the link is also set to desirable or active mode, the port will form an EtherChannel bundle.

C. On: In on mode, the port does not use LACP for negotiation. The port simply bundles the physical links into an EtherChannel without any negotiation. This mode is not recommended as it can lead to misconfiguration and network issues.

D. Auto: In auto mode, the port will try to negotiate using LACP if it detects a LACP device on the other end of the link. If no LACP device is detected, the port will form an EtherChannel bundle without LACP.

E. Active: In active mode, the port actively initiates the LACP negotiation process and sends LACP messages to the other end of the link. If the other end of the link is also set to active or desirable mode, the port will form an EtherChannel bundle.

Therefore, the correct answer to the question is A. Passive mode enables LACP only if a LACP device is detected on the other end of the link. If the other end of the link is not configured for LACP, the port will still form an EtherChannel bundle without LACP.