350-401 Question #1165: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. After unsuccessfully configuring an EtherChannel link, an engineer enables debugging. Which action will resolve the issue?

Options

• AConfigure the EtherChannel members in desirable mode.
• BSet the EtherChannel to mode on.
• CSet the EtherChannel to mode active.
• DConfigure the EtherChannel members in passive mode.

Explanation

To resolve an EtherChannel issue using PAgP, configuring an interface in desirable mode actively initiates negotiation to form the channel.

Common mistakes.

• B. Setting the EtherChannel to mode 'on' forces the interface into an EtherChannel without any negotiation, requiring both ends to be in 'on' mode, and will prevent formation if any mismatch in negotiation modes exists.
• C. Setting the EtherChannel to mode 'active' is specific to LACP (Link Aggregation Control Protocol) and is incompatible with PAgP, thus it would not resolve a PAgP-related EtherChannel issue.
• D. Configuring EtherChannel members in passive mode for PAgP puts the interface in a listening state; if both sides are passive, no EtherChannel will form because neither side actively initiates negotiation.

Concept tested. EtherChannel PAgP negotiation modes

Reference. https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3750x_3560x/software/release/12-2_55_se/configuration/guide/3750x_cg/swethchl.html

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