In Juniper Mist campus fabric architectures, the location of the Layer 3 gateway (IRB interface) differentiates centrally-routed bridging (CRB) from edge-routed bridging (ERB):

In CRB, the gateway resides at the core layer --- routing occurs centrally, and access/distribution layers perform Layer 2 bridging.

In ERB, the gateway moves to the edge (distribution layer), enabling routing to occur closer to endpoints, improving performance and scalability.

''In a centrally-routed bridging (CRB) topology, Layer 3 gateways reside at the core. When transitioning to an edge-routed bridging (ERB) design, the Layer 3 gateways are moved to the distribution layer, closer to the access switches and clients.''

Therefore, when moving from a core-distribution CRB to an ERB model, the gateway moves from the distribution to the access layer in campus terms (edge = access).

Option A: Incorrect --- ERB gateways are not at the distribution layer only.

Option B: Incorrect --- opposite direction.

Option C: Correct --- the gateway moves from distribution to access (edge).

Option D: Incorrect --- this describes CRB, not ERB.

Juniper Mist AI for Wired -- Campus Fabric Architecture Models (CRB vs ERB)

Juniper Validated Design -- Campus Fabric EVPN-VXLAN Gateway Placement

Junos OS EVPN-VXLAN Deployment Guide

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