Case Study: Global Retail Corp Global Retail Corp (GRC) is a multinational retailer with over 500 stores. They are upgrading their campus network infrastructure at their corporate headquarters. The headquarters consists of two buildings connected by redundant dark fiber links. The primary goals of the project are to achieve a fully redundant, active-active core network that can survive the complete failure of a core switch or an entire building's network closet without any service interruption. The solution must provide a single, logical default gateway for all VLANs to simplify routing for the access layer switches. The proposed solution uses two Aruba CX 8400 switches, one in each building, as the core. The access layer consists of Aruba CX 6300 series switches. The network team is debating between VSF and VSX for the core switches. They need to ensure that control plane failures on one switch do not impact the other and that firmware updates can be performed without network downtime. Given the explicit requirements for control plane separation and zero-downtime updates, which technology should be chosen for the core, and what is the primary mechanism that provides the active-active default gateway? ```mermaid graph TD subgraph Building A CoreA[CX 8400 - A] AccessA1[CX 6300] AccessA2[CX 6300] end subgraph Building B CoreB[CX 8400 - B] AccessB1[CX 6300] AccessB2[CX 6300] end CoreA -- ISL --- CoreB CoreA -- Keepalive --- CoreB AccessA1 -- LACP --> CoreA AccessA1 -- LACP --> CoreB AccessB1 -- LACP --> CoreA AccessB1 -- LACP --> CoreB ```