A customer currently has a three-tier architecture in which aggregation switches are the default gateways. Pairs of aggregation switches use VRRP. You are migrating to an L2 two-tier architecture in which the core switches are the default gateways. How should you migrate the default gateway functionality?

The most effective and modern method for this migration is to leverage Virtual Switching Extension (VSX) Active Gateway on the new core switches. To ensure a seamless transition with minimal disruption to end devices (servers), it is critical to reuse the existing default gateway IP address. By configuring the VSX Active Gateway with the same virtual IP address previously used by VRRP, servers do not need to be reconfigured. This approach migrates the gateway functionality directly to the intended, modern, active-active architecture. While reusing the existing VRRP MAC address is also a best practice for a truly hitless migration, reusing the IP address is the most critical element presented in the correct option.

A. Assigning new gateway IP addresses via DHCP is highly disruptive, as it would require reconfiguring all servers, many of which likely use static IP assignments.
C. While technically possible, adding new core switches to an old VRRP group is not the recommended best practice. It implements a legacy protocol on a new core and is not the documented procedure for migrating to a superior VSX architecture.
D. Configuring a new default gateway IP address is incorrect because it would necessitate reconfiguring every server on the network, causing significant operational disruption.

1. ArubaOS-CX 10.10 VSX Configuration Guide

Page 101

"Migrating from an existing VRRP active/standby deployment to a VSX active/active deployment".

The official procedure states: "On both VSX switches

configure the active-gateway. To minimize traffic disruption

configure the same virtual IP address as the VRRP virtual IP address." This directly supports reusing the IP address with the new VSX Active Gateway feature

as described in option B. The guide details a cutover process

not an integration into the existing VRRP group (as suggested in option C).

2. Aruba Validated Solution Guide - Campus Network Design for Scalability and Resiliency (AOS-CX 10.06)

Chapter 3: Core Layer Design

Section: "Layer 3 Gateway".

This guide establishes VSX with Active Gateway as the standard

best-practice design for providing default gateway redundancy in a modern two-tier campus core. It states

"In a VSX pair

the active gateway feature provides default gateway redundancy... Both VSX peers are active and forward traffic sent to the virtual IP and virtual MAC address." This confirms that migrating to VSX (Option B) is the correct architectural goal

not continuing to use VRRP (Option C).