A Link Aggregation Group (LAG) bundles multiple physical network links into a single logical link. This technique, standardized as IEEE 802.1AX (formerly 802.3ad), serves two main purposes for high availability. First, it increases the total available bandwidth by combining the capacity of all member links. Second, it provides redundancy; if one physical link within the LAG fails, traffic is automatically redistributed among the remaining active links without disrupting the logical connection. This ensures continuous operation and resilience against individual link failures.

B. LAG does not reroute to a separate backup path; it redistributes traffic over the remaining links within the same logical bundle.

C. LAG is a Layer 2 technology that aggregates physical links, not Layer 3 routing information between routers.

D. LAG provides link-level failover, not device-level failover. Protocols like VRRP or device clustering are used for automatic device failover.

1. Juniper Networks TechLibrary. (2023). Understanding Aggregated Ethernet Interfaces. This document states

"Aggregated Ethernet bundles Ethernet links to form a single link-layer interface... for increased bandwidth and for redundancy."

2. IEEE Std 802.1AX-2014. (2014). IEEE Standard for Local and metropolitan area networks--Link Aggregation. IEEE Standards Association. Section 1

"Overview

" describes the standard's purpose as allowing "one or more links to be aggregated together to form a Link Aggregation Group

such that a MAC Client can treat the Link Aggregation Group as if it were a single link."