Data Center Fabric and HCI Architecture

This module defines the physical and logical structure of the enterprise data center. It focuses on the fabric that interconnects compute, storage, and security layers, and the hyper converged infrastructure blocks that host the platform, application, database, and Kubernetes workloads defined in the tiering model.

The objective is to provide a consistent pattern that scales across the Primary DC, Disaster Recovery DC, and the Out-of-Region DR site.

Fabric Overview

Modern enterprise data centers use a spine and leaf topology to ensure predictable performance, non-blocking east and west traffic, and flexible scaling characteristics. This architecture provides:

• Deterministic latency for all workloads
• Simple horizontal expansion by adding leaf switches
• Failure domain containment
• High availability through redundant paths at every layer

The spine and leaf fabric serves as the foundation for all HCI blocks. It provides the underlying connectivity for:

• Platform services such as identity, logging, and monitoring
• Application hosting
• Database and storage systems
• DMZ and security inspection layers
• Kubernetes clusters

Standard Fabric Pattern

All data centers follow a uniform pattern:

• A leaf layer that connects servers, HCI nodes, and service appliances
• A spine layer that interconnects all leaves
• Equal cost multipath routing for predictable performance
• Distinct VLAN or overlay segments for each major platform tier

This structure ensures that any server or workload can reach any other server or workload with minimal and consistent network hops, regardless of physical placement.

HCI Block Structure

Hyper converged infrastructure allows compute, storage, and networking resources to be delivered as a single unit. This architecture treats each logical function as a separate HCI block. Each block has its own performance profile, security requirements, and failure domain.

The standard HCI blocks are:

• Infrastructure Block
• DMZ Block
• Application Hosting Block
• Database and High Performance Storage Block
• Kubernetes Platform Block

Each block consists of:

• A node cluster with local resilient storage or shared distributed storage
• Network uplinks connected to redundant leaf switches
• VLAN and segmentation boundaries aligned to the enterprise tiering model
• Resource pools dedicated to the purpose of each block

1. Infrastructure HCI Block

This block hosts foundational services that the entire enterprise depends on, including:

• DNS and NTP
• Directory services
• PKI
• Patch and configuration management
• Backup and restoration platforms
• Logging, SIEM, and monitoring collection points
• Firewall and network management systems
• Automation and orchestration platforms

The Infrastructure Block is treated as the most critical internal zone. It requires strong access controls, strict segmentation, and continuous monitoring.

2. DMZ HCI Block

The DMZ Block is an isolated cluster that hosts:

• Reverse proxy services
• Load balancing
• Web application firewalls
• External gateway components for VDI
• API gateways
• Telemetry forwarders for SIEM and monitoring

The DMZ connects to the external network through edge firewalls and to internal application tiers through controlled and monitored trust boundaries. No lateral traffic from DMZ to internal networks is permitted without explicit policy and security inspection.

3. Application Hosting HCI Block

The Application Block is the default landing zone for business applications. It supports:

• Internal web servers
• Internal service endpoints
• Mid-tier APIs
• Integration services
• Application runtimes such as .NET, Java, and Python platforms

Segmentation controls isolate applications from each other when required. Application workloads communicate with the Database Block or other internal services through identity and policy governed paths.

4. Database and High Performance Storage Block

This block hosts:

• Relational database systems
• High performance storage arrays
• Replication engines
• Messaging and data pipelines that have strict performance requirements

Database access is controlled at the network, identity, and application layers. Only the Application Block and Infrastructure Block may reach database assets according to strict access policies.

This block is frequently deployed with higher performance node profiles, larger memory footprints, additional NVMe storage, and dedicated storage replication links between sites.

5. Kubernetes Platform Block

The Kubernetes Block supports containerized workloads, including:

• Microservices
• Internal APIs
• Batch workloads
• Development and staging environments
• High availability internal platform services

Depending on organizational maturity, the Kubernetes Block may integrate:

• Network policies for microsegmentation
• Service meshes for identity-based routing
• Ingress controllers with WAF capability
• Persistent storage through CSI drivers
• Registry, artifact, and scanning services

Network Segmentation and Logical Boundaries

Segmentation is applied consistently across all blocks. This includes:

• Separate VLANs for management, storage replication, application traffic, and backup traffic
• Role based ACLs and firewall policies at the leaf or firewall boundary
• East and west restrictions inside and across blocks
• Dedicated interface profiles for HCI storage interconnects
• Traffic classification for monitoring and telemetry

All segmentation boundaries align directly with the tiering model defined in the overall reference architecture. Identity-aware, microsegmented, and continuously verified controls ensure no lateral movement beyond permitted flows.

Storage Architecture and Replication

HCI blocks rely on resilient and synchronized storage. Typical storage patterns include:

• Distributed storage via vSAN, Nutanix, or similar engines
• Synchronous replication between Primary and DR for Tier 1 workloads
• Asynchronous replication to Out-of-Region DR for survivability requirements
• Storage policy based management for performance tiers
• Snapshots and recovery points tied to RPO/RTO classifications

Database workloads may use:

• Native database replication for high availability
• Log shipping or snapshot replication for lower tiers
• Application aware consistency groups when needed

High Availability Considerations

Availability must exist at multiple layers:

• Leaf switches deployed in redundant pairs
• Spine switches deployed in redundant pairs
• HCI clusters with N+1 or higher node redundancy
• Redundant uplinks between HCI nodes and leaf switches
• Distributed storage with automatic failover
• Dual power feeds and independent UPS systems

Each block maintains its own local failover capabilities and can also take advantage of inter-site recovery when required.

Fabric Operations and Observability

Operational standards apply across all data centers:

• Consistent switch configuration templates
• Automated configuration management and validation
• Telemetry and flow logs exported to centralized SIEM
• SNMP, API, and streaming telemetry for performance and health monitoring
• Automated alerting for path, node, or storage anomalies

Integration with the overall Zero Trust strategy ensures:

• Continuous verification of fabric health
• Monitoring of control plane and data plane paths
• Detection of lateral movement attempts

Implementation Options

Vendors and products that support this architecture include the following examples. Equivalent alternatives may be used if they meet the functional requirements.

Fabric and Switching

• Cisco Nexus or Catalyst switching
• Arista spine and leaf platforms
• Juniper QFX and EX series
• HPE or Aruba switching platforms

HCI Platforms

• VMware vSphere with vSAN or VxRail appliances
• Nutanix AHV or ESXi based clusters
• Azure Stack HCI for hybrid focused environments

Storage and Replication

• VMware vSAN replication
• Nutanix replication
• Dell PowerStore or PowerFlex systems
• HPE Alletra or Nimble arrays

Kubernetes Integrations

• VMware Tanzu
• Red Hat OpenShift
• Rancher with upstream Kubernetes
• Managed registries and scanning tools that meet enterprise security needs

Related Entries

• Enterprise Hybrid HCI Platform Overview - Foundational reference architecture
• Multi-Site Hybrid Core Architecture - Network connectivity patterns
• Platform Services: Identity and Security Operations - Services layer built on this fabric

This fabric and HCI model provides the physical and logical foundation for the higher tier platform services described in the next module.