Which protocol bundles multiple physical links between switches or servers into one logical link for increased bandwidth and redundancy?

Which protocol bundles multiple physical links between switches or servers into one logical link for increased bandwidth and redundancy?

• A. GLBP
• B. VRRP
• C. FHRP
• D. LACP

Answer: (D)

Bundling multiple physical links into a single logical connection is achieved through a link aggregation protocol. The protocol that does this is LACP (Link Aggregation Control Protocol). LACP negotiates with the peer switch or server, groups several Ethernet interfaces into one port channel (also called EtherChannel), and makes them function as one high-bandwidth link. This setup increases total available bandwidth and provides redundancy because if one physical link fails, the others continue carrying traffic, keeping the link active. For this to work, both ends must support and agree on the same aggregation method, and traffic is distributed across the member links using a hashing mechanism. The other options are about gateway redundancy, not link aggregation: they ensure a backup default gateway or load balancing among routers, not combining multiple physical links into a single logical path.

Bundling multiple physical links into a single logical connection is achieved through a link aggregation protocol. The protocol that does this is LACP (Link Aggregation Control Protocol). LACP negotiates with the peer switch or server, groups several Ethernet interfaces into one port channel (also called EtherChannel), and makes them function as one high-bandwidth link. This setup increases total available bandwidth and provides redundancy because if one physical link fails, the others continue carrying traffic, keeping the link active. For this to work, both ends must support and agree on the same aggregation method, and traffic is distributed across the member links using a hashing mechanism.

The other options are about gateway redundancy, not link aggregation: they ensure a backup default gateway or load balancing among routers, not combining multiple physical links into a single logical path.