1Architecture

• 1.1Enterprise network design principles and high availability

  Covers enterprise design models—2-tier (collapsed core), 3-tier, fabric, and cloud—together with redundancy via FHRP, SSO (Stateful Switchover), and stacking/VSS, framed as the design judgment of "which form of redundancy actually satisfies this availability requirement" and "what is lost during a switchover."

• 1.2Cisco Catalyst SD-WAN

  Covers how responsibilities are split across vSmart (control), vManage (SD-WAN Manager) (management), vBond (orchestration), and cEdge/vEdge (data plane); route distribution via OMP; and the benefits of centralized policy and circuit-cost optimization against the limits of controller dependence—framed as diagnosing "which component to suspect" during a fault.

• 1.3Cisco SD-Access

  Covers the three-layer structure of SD-Access—LISP for the control plane (mapping EIDs to RLOCs), VXLAN for the data plane (L2-over-L3 encapsulation), and Cisco TrustSec/SGT for policy—along with the division of labor between the underlay and the overlay, and the fabric border as the interconnection point with the traditional campus, framed as isolating "where exactly is this happening."

• 1.4Interpreting QoS configurations

  Covers classification that identifies traffic, marking (DSCP/CoS) that stamps the result into headers, queuing that decides what leaves first under congestion, and the choice between policing (dropping excess) and shaping (delaying it)—framed as diagnosing "how does this configuration treat voice" and "why did retransmissions increase."