Cisco CCNA (200-301)Network AccessMedium
On SW1, interfaces Gi0/1 and Gi0/2 are configured with 'channel-group 1 mode passive'. On SW2, the matching interfaces Gi0/1 and Gi0/2 are also configured with 'channel-group 1 mode passive'. What is the result?
- ALACP negotiates normally and the EtherChannel forms with both sides passive
- BThe ports remain as separate individual links because neither side sends LACP packets first
- CThe switches automatically fall back to PAgP to form the channel
- DOnly one of the two links bundles while the other stays down
Show answer & explanationAnswer & explanation
Correct answer: B. The ports remain as separate individual links because neither side sends LACP packets first
LACP passive mode means the port will only respond to LACP packets, not initiate them. If both ends are passive, neither side ever sends the initial LACPDU, so negotiation never starts and no EtherChannel forms.
Why the other options are wrong
- A. Passive-passive never triggers negotiation since neither side speaks first.
- C. PAgP is a separate proprietary protocol and is not a fallback for LACP.
- D. Without negotiation, none of the links bundle, not just one.
LACP Active/Passive Modes
LACP EtherChannel requires at least one side configured as 'active' to initiate negotiation; 'passive' only responds.
- active + active = forms channel
- active + passive = forms channel
- passive + passive = never forms channel
- PAgP uses desirable/auto instead of active/passive
Memory trick: Two passives just wait for someone to speak first — silence forever.