Micro BFD, also known as BFD over Link Aggregation Group (LAG) member links, is designed to overcome the limitations of running a single BFD session over an entire LAG interface. The primary goal is to provide rapid failure detection and verify data plane continuity for each individual member link within the bundle. This is achieved by establishing a separate and independent BFD session on every physical member link. If a micro BFD session detects a failure on a specific link, that link is immediately removed from the LAG's forwarding table, preventing traffic from being black-holed, while the remaining healthy links continue to forward traffic.

A. Micro BFD is not selective; its purpose is to monitor all member links, irrespective of their bandwidth, to ensure complete bundle integrity.

B. While aggressive timers are a feature of BFD, a specific value like "3x3 ms" is a configuration detail, not a fundamental goal of the protocol.

D. Monitoring just "any" member link is insufficient; the goal is to monitor all links comprehensively to prevent any single point of failure within the bundle.

1. Cisco Systems

Inc.

IP Routing: BFD Configuration Guide

Cisco IOS XE Cupertino 17.9.x

"BFD over Link Aggregation Group (LAG) Interfaces" section. The guide states

"The BFD over LAG feature allows BFD sessions to monitor individual member links in a LAG. This is also known as micro BFD... A separate BFD session is created for each member link". This supports that each link must run BFD (E) to monitor individual links (C).

2. Cisco Systems

Inc.

Cisco Nexus 9000 Series NX-OS Unicast Routing Configuration Guide

Release 10.3(x)

"Configuring BFD" chapter

"BFD for Link Aggregation (LAG)" section. This document specifies

"BFD for LAG provides fast failure detection on a per-member link basis. A separate BFD session runs on each member of a port channel." This directly validates verifying continuity for each link (C) and running BFD on each member (E).