In a standard leaf-spine architecture, every leaf switch connects to every spine switch. The design specifies six racks, each with a pair of VSX Leaf switches, resulting in a total of 12 physical leaf switches (6 racks × 2 switches/rack). There are two spine switches.

The total number of physical point-to-point (P2P) links is calculated by multiplying the number of leaf switches by the number of spine switches: 12 leaves × 2 spines = 24 links.

Each P2P link requires two IP addresses, one for the interface on the leaf switch and one for the interface on the spine switch. Therefore, the total number of required addresses is 24 links × 2 addresses/link = 48 addresses.

A. 12: This represents the total number of physical leaf switches in the topology, not the number of IP addresses for the interconnects.

B. 96: This is double the correct number of addresses and does not correspond to any logical calculation for the described network topology.

C. 24: This represents the total number of physical P2P links between the leaf and spine layers, not the total number of IP addresses required.

1. Aruba Validated Solution Guide: Data Center Network with Aruba CX Switches (February 2021). The guide's topology diagrams (e.g.

Figure 1

page 8) illustrate the fundamental principle of leaf-spine design where each leaf switch has a physical connection to every spine switch. The IP addressing scheme for the underlay network is based on these physical links.

2. ArubaOS-CX EVPN-VXLAN Configuration Guide (for ArubaOS-CX 10.11). In the "Underlay and overlay design" section of Chapter 1

it states: "In a leaf-spine topology

the underlay consists of point-to-point links between the leaf and spine switches." This confirms that each physical connection is a distinct P2P link requiring its own addressing.

3. Aruba Campus Access for Large Networks Validated Solution Guide (May 2022). On page 21

in the "IP Addressing" section for the L3 access design (a leaf-spine model)

the guide recommends using /31 subnets for point-to-point links between access (leaf) and aggregation (spine) layers. A /31 subnet explicitly allocates two IP addresses

one for each end of the link

reinforcing the calculation of 2 addresses per link.