Unit 6: Bridging, VLANs, SVIs, and STP

Per-unit concept, checklist, and command drill page

Unit 6 of 14

Objective

Operate Layer 2 segmentation and Layer 3 VLAN routing with stable loop prevention.

Concept Notes

L2/L3 boundaries in Cumulus are easy to configure but equally easy to misconfigure under time pressure. This unit emphasizes deterministic segmentation, loop safety, and gateway continuity.

In AI clusters, transient loops or VLAN leakage can create burst loss that appears as GPU training instability. Stable bridging policy and fast verification workflows prevent that failure mode.

Coverage Checklist

Bridge concepts and VLAN-aware bridge mode scaling.
Access and trunk behavior with native VLAN handling.
MAC learning and aging behavior in bridge domains.
SVI design for inter-VLAN routing and gateway roles.
RSTP/PVRST options and root/edge policy controls.
BPDU guard and loop-prevention operational guardrails.

Practice Outcomes

Build trunk and access templates without VLAN leakage.
Validate inter-VLAN routing path through SVI gateway points.
Harden edge ports to prevent accidental loop introduction.

Command Drills

nv set bridge domain br_default vlan 1-3 && nv config apply

Set VLAN-aware bridge scope in one place.

nv show bridge domain br_default mac-table

Confirm MAC learning and forwarding behavior.

nv show bridge domain br_default stp

Verify spanning-tree convergence and role assignments.

Navigation

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