What is LACP (Link Aggregation Control Protocol, IEEE 802.3ad), and what is the difference between active and...

Question

What is LACP (Link Aggregation Control Protocol, IEEE 802.3ad), and what is the difference between active and passive LACP modes?

Accepted Answer

LACP negotiates the formation of an EtherChannel (port-channel) between two switches or between a switch and a server; active mode initiates LACP negotiation by sending LACP PDUs; passive mode waits for the partner to initiate. For a channel to form: at least one side must be active (passive-passive will not form; active-active or active-passive will form)

Answer

LACP active mode requires a crossover cable; passive mode works with straight-through cables only

Answer

LACP active mode uses one physical link at a time; passive mode uses all links simultaneously for maximum throughput; attenuation increases as cables get shorter because reflections dominate. Longest-prefix match means the route with the shortest subnet mask always wins. OSPF areas exchange full topology databases so every router sees every link in every area

Answer

In LACP active mode, the switch chooses the highest-bandwidth link; passive mode uses the lowest-bandwidth link, because a Layer 2 loop dissipates on its own because frames expire after 255 hops. OSPF advertises routes over TCP port 179 using incremental keepalive updates. The native VLAN's frames are double-tagged for extra integrity on trunks across vendors

What is LACP (Link Aggregation Control Protocol, IEEE 802.3ad), and what is the difference between active and passive LACP modes?

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What is LACP (Link Aggregation Control Protocol, IEEE 802.3ad), and what is the difference between active and passive LACP modes?

Where this fits in the Network Fundamentals exam

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