Cisco DC design ACI Multi-Pod

The solution leverages Cisco ACI’s Multi-Pod architecture to connect two geographically dispersed data center pods (Site A and Site B) into a single ACI fabric.

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Fabric Design

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• Each pod consists of a spine-leaf architecture with Cisco Nexus 9000 switches

• Each pod has its own dedicated pair of APIC controllers, managing the fabric at a local level.

• A shared control plane is used, allowing both pods to be seen as a single ACI fabric.

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Inter-Pod Network (IPN)

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• The two pods are connected using an IPN, which acts as the Layer 3 interconnect between the two sites.

• The IPN ensures seamless communication between the spines of each pod and manages the traffic between the two locations.

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Network-Centric Approach

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The network-centric design focuses on traditional networking constructs and is based on the following:

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VRFs and Bridge Domains (BDs)
 

• VRFs are used to provide layer-3 segmentation, supporting different business units.

• Bridge Domains are mapped to specific VLANs, allowing the organization to maintain the same VLAN structure as the traditional network.

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Layer 3 Connectivity (L3Out)

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• L3Out provides external routing between the ACI fabric and external networks (e.g., WAN, MPLS).

• Each pod will have its own L3Out configuration to interface with external routers.

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Inter-Pod Routing

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• The pods are interconnected via an IPN that uses Layer 3 routing protocols like OSPF or BGP.

• VRFs and subnets are extended between the pods, allowing workloads to move freely between Site A and Site B.

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High Availability and Disaster Recovery

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To ensure high availability and disaster recovery, the Multi-Pod solution enables active-active traffic flows between the two pods.

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Active-Active Traffic

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• Both pods will handle traffic simultaneously, with workloads distributed across both sites.

• This ensures redundancy; in the event of a failure in one site, traffic can continue to flow through the other.

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Inter-Pod Failover

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• In case of failure in either site, the other pod will automatically take over the traffic with minimal downtime.

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Automation and Zero-Touch Deployment

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Cisco ACI provides automation tools that simplify the management and operations of both pods.

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Automated Deployment

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• ACI's zero-touch provisioning simplifies the onboarding of new devices into the network.

• Consistent policies are applied across both pods using APIC, reducing operational complexity.

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Centralized Policy Management

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• Despite the physical separation, both pods are managed centrally through the APIC controllers, allowing for uniform policy implementation.

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Security and Micro-Segmentation

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The network-centric approach ensures secure network segmentation while enabling scalability.

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Tenant Isolation

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• Each business unit or application group is placed into a separate tenant within ACI, ensuring traffic isolation and better security control.

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Micro-Segmentation

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• Contracts between EPGs (End Point Groups) ensure that only allowed traffic can flow between workloads, further securing the network.

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Implementation Phases

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Phase 1: Planning and Design

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• Assess the current infrastructure and identify the necessary upgrades to support Cisco ACI Multi-Pod.

• Define network requirements, including VLAN, IP addressing, and VRF configuration, in line with the network-centric approach.

• Design the IPN, ensuring sufficient bandwidth and low latency for inter-site traffic.

 

Phase 2: Pod Deployment

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Site A (SH1-DC) and Site B (SH2-DC) are configured as independent pods with:

• Spine-leaf topology using Cisco Nexus 9000 series switches.

• Dedicated APIC controllers for each pod.

 

Phase 3: IPN Configuration

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• Configure the IPN for connectivity between the two pods. This Layer 3 connection uses a WAN link between SH1-DC and SH2-DC, ensuring low-latency, high-bandwidth communication.

• Routing protocols such as BGP or OSPF are configured for dynamic routing between the pods.

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Phase 4: Policy and VRF Configuration

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• Set up tenants, VRFs, and bridge domains across both pods.

• Extend VRFs between the pods to allow seamless workload movement and routing between sites.

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Phase 5: Testing and Validation

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• Test the end-to-end connectivity between the two pods.

• Ensure traffic can flow between VRFs and BDs across both sites.

• Perform failover testing to verify disaster recovery capabilities.

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Phase 6: Go-Live and Monitoring

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• Transition live workloads to the new Multi-Pod infrastructure.

• Deploy monitoring tools to track network health, performance, and security.

 

Challenges and Solutions

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Inter-Pod Latency

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• Challenge: Ensuring low latency between the two geographically separated sites.

• Solution: High-speed IPN links with sufficient bandwidth were deployed to minimize latency, along with QoS (Quality of Service) configuration to prioritize critical traffic.

 

Network Complexity

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• Challenge: Managing traditional networking constructs in a highly automated ACI fabric.

• Solution: The network-centric approach allowed the organization to retain VLANs and subnets familiar to their existing network operations team, while APIC automation simplified overall management.

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Disaster Recovery Testing

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• Challenge: Ensuring minimal downtime during failover between pods.

• Solution: Failover testing and validation were conducted to simulate various failure scenarios, ensuring the business continuity plan was robust.

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Business Benefits

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• Unified Fabric: The Cisco ACI Multi-Pod architecture enables a unified fabric across two data centers, simplifying management and enabling seamless inter-pod communication.

• Scalability: The Multi-Pod design allows for the easy addition of new data centers or expansion within existing pods.

• High Availability: Active-active configurations ensure that traffic can flow across both data centers simultaneously, enhancing redundancy and disaster recovery.

• Improved Operational Efficiency: The automation features of Cisco ACI streamline operations, from device onboarding to policy configuration, reducing manual errors and improving response times.

• Simplified Policy Management: The centralized control via APIC and MSO allows the organization to maintain consistent security and networking policies across both sites, reducing the complexity of managing multi-site environments.

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Conclusion

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The Cisco ACI Multi-Pod deployment provided the financial services organization with a unified, scalable, and highly available network infrastructure across its two data centers. The network-centric design ensured the organization's reliance on traditional IP networking constructs while benefiting from ACI’s automation, security, and scalability features. This approach ensures the network is future-proofed for potential expansions and evolving business needs.