The exhibit illustrates an Edge-Routed Bridging (ERB) architecture, also known as a leaf-routed or ToR-routed model. The defining characteristic of this design is the placement of the Layer 3 gateway functionality on the leaf switches. As shown in the diagram, "L3 Gateway" is present on Leaf 1 and Leaf 2. This allows for inter-VLAN routing to occur at the edge of the fabric, directly on the ingress leaf device. This optimizes east-west traffic patterns within the data center by preventing traffic from having to traverse to the spine layer for routing.

A. The diagram lacks the specific details of MAC-in-MAC encapsulation that would be required to identify it as a PBB-EVPN architecture.

C. Over-The-Top (OTT) is a general term for an overlay network; it does not describe the specific routing architecture (i.e., where the L3 gateway resides) like ERB or CRB do.

D. In a Centrally-Routed Bridging (CRB) architecture, the L3 gateway is located on the spine devices, and the leaf devices perform only Layer 2 functions. The exhibit clearly shows L3 gateways on the leafs.

1. Juniper Networks. (2021). Day One: Data Center Fabric with EVPN and VXLAN. Chapter 2

"EVPN-VXLAN Architecture"

Section "Edge-Routed Bridging Overlay". This section states

"In an ERB overlay

the VXLAN L3 gateway is implemented on the leaf devices... This model is also known as a host-based overlay or a top-of-rack (ToR) based overlay." This directly corresponds to the provided exhibit.

2. Juniper Networks TechLibrary. (2023). EVPN-VXLAN Design and Implementation Details Guide. Section: "EVPN-VXLAN Fabric Architecture Models". This guide contrasts the two primary models: "In an edge-routed bridging (ERB) overlay

the Layer 3 gateway is on the leaf devices... In a centrally-routed bridging (CRB) overlay

the Layer 3 gateway is on the spine devices." The exhibit aligns with the ERB definition.

3. Juniper Networks TechLibrary. (2024). Understanding EVPN-VXLAN Edge-Routed Bridging Overlay Model. This document explicitly defines the architecture: "In an edge-routed bridging overlay

the default Layer 3 gateway resides on the leaf devices. The leaf devices

therefore

provide both Layer 2 and Layer 3 forwarding." This confirms the analysis of the diagram.