An engineer issues the `show etherchannel summary` command on Switch-A and observes that the logical interface `Port-channel 1` displays a status flag of `SD` (Layer 2, Down), with all member physical interfaces marked with the flag `I` (Stand-alone). Physical connectivity between the switches is up and running. Which configuration on the interconnected switches is the root cause of this operational state?
- ASwitch-A is configured with `channel-group 1 mode active` while Switch-B is configured with `channel-group 1 mode passive`.
- Both switches are configured with `channel-group 1 mode passive` on their respective physical member interfaces.Cevap
- CThe physical member interfaces on Switch-A are configured with native VLAN 10, whereas Switch-B is configured with native VLAN 20.
- DSwitch-A is configured with `channel-group 1 mode active` while Switch-B is configured with `channel-group 1 mode desirable`.
Cevap
Both switches are configured with LACP passive mode on their connected physical member interfaces.
Link Aggregation Control Protocol (LACP) requires at least one participating switch interface to actively initiate negotiation. When both endpoints are set to `passive` mode (`channel-group mode passive`), neither device sends LACP packets. Consequently, LACP negotiation never completes, leaving the port-channel interface down (`SD`) and placing the individual member interfaces in stand-alone (`I`) operational state.
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Anahtar Kavram
LACP Operational Modes and Negotiation Rules
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