Juniper's official Campus Fabric IP Clos design for Mist Wired Assurance defines that the 3-stage IP Clos topology eliminates the traditional distribution layer entirely. This architecture is intended for smaller campus environments that do not need an intermediate distribution layer between the access and core.

''Juniper's Wired Assurance supports 3-Stage and 5-Stage IP Clos deployments. The 3-Stage IP Clos is targeted towards deployments that do not require a Distribution Layer and have smaller scale requirements.''

Because the distribution layer is not present, the only hierarchical connection in a 3-stage campus fabric is between the core and access layers. Traffic is routed directly at the access layer, and each access switch acts as a Layer-3 gateway (IRB) for its VLANs.

''In a campus fabric IP Clos architecture, Mist provisions Layer-3 (L3) integrated routing and bridging (IRB) interfaces on the access layer. All the access switches are configured with the same IP address for each L3 subnet.''

Additionally, the Juniper documentation explains that point-to-point links are configured between layers, and in the case of the 3-stage design (with no distribution), this means between the core and access devices:

''The point-to-point links between each layer utilize /31 addressing to conserve addresses.''

Therefore, the correct statement is C: The core layer is connected to the access layer.

Options A and B incorrectly mention a distribution layer that does not exist in this topology.

Option D is incorrect because core (spine) devices in a Clos fabric are not interconnected with each other.

Juniper Mist AI for Wired -- Campus Fabric IP Clos Architecture Guide

Juniper Mist AI for Wired -- Campus Fabric IP Clos Workflow

Juniper Mist AI for Wired -- Configure Campus Fabric IP Clos

Juniper Validated Design -- Campus Fabric IP Clos Deployment Types