Moving from Cisco to Arista: Step-by-Step Migration Guide for Data Centers

The decision to initiate a major network overhaul, particularly one involving a shift from an incumbent vendor like Cisco Systems to a focused innovator like Arista Networks, is a pivotal strategic moment. Driven by the need for agility, performance, and reduced operational complexity, many enterprise and cloud network professionals are evaluating the Cisco to Arista migration.

This guide provides network engineers and IT decision-makers with a comprehensive technical roadmap, covering the key planning steps, automation tools, financial implications, and technical hurdles involved in switching to the Arista Extensible Operating System (EOS) environment.

Table of Contents

• Part 1. Why Consider Moving from Cisco to Arista
• Part 2. Cisco vs Arista Ecosystem Overview: Performance, OS, and Architecture
• Part 3. Migration Planning: Considerations and Risk Assessment
• Part 4. Step-by-Step Migration Guide and Interoperability Gotchas
• Part 5. Automation, Tools, and Configuration Conversion
• Part 6. Cost, Licensing, and Long-Term Support
• Part 7. Best Practices and Risk Mitigation
• Part 8. Summary
• Common Questions About Cisco to Arista Migration

Part 1. Why Consider Moving from Cisco to Arista

Network migration is often driven by the necessity to modernize legacy systems and address future business needs, especially those related to cloud infrastructure and AI workloads. Organizations consider the Cisco replacement primarily due to several critical drivers:

1. Technology Upgrades and Performance: Enterprises seek technologies offering agility, scalability, higher speed, and lower latency, particularly for high-performance computing (HPC) or high-frequency trading (HFT). Arista specializes in manufacturing some of the fastest switches on the market, optimized for hyperscale performance.
2. Operational Simplicity and OPEX Reduction: Managing proprietary, complex legacy infrastructure often increases OPEX. Arista’s unified software stack, built upon a single, consistent EOS across all platforms, simplifies design and operations.
3. Avoiding Vendor Lock-In: Organizations prefer open standards implementation to enhance agility, prevent dependency on a single vendor's solutions, and promote cost savings through fair competition. Cisco is known for locking customers into its proprietary chips and software.
4. EOL and Security: Hardware refresh cycles, systems nearing End-of-Life (EOL), and concerns over slow vulnerability management from incumbent vendors often prompt a shift to secure, supported platforms. Arista focuses on a unified, consistent product strategy.

Part 2. Cisco vs Arista Ecosystem Overview: Performance, OS, and Architecture

Part 3. Migration Planning: Considerations and Risk Assessment

Cisco to Arista migration requires careful planning to minimize disruption. Arista Services recommends a phased approach: simplify, virtualize, and automate.

Key Planning Factors

1. Discovery and Baseline: Gather extensive data to establish a comprehensive baseline of the legacy Cisco environment, including hardware inventory, network services (VLANs, VRFs, routing), operational states, and performance metrics.
2. Normalization and Standardization: Convert Cisco proprietary features to open standards, including routing protocols and Layer 2 protocols.
3. Choosing the Migration Technique:
   • Per-Device Migration (RIP and Replace): Replace equipment and integrate new devices into the legacy network while maintaining largely identical design. Higher risk due to interoperability issues.
   • Per-Design Migration (Greenfield/Side-by-Side): Deploy Arista fabric in parallel, interconnect side-by-side, gradually steer traffic from old to new path. Recommended for Data Center/Campus environments.
4. Risk Mitigation: The Value of Digital Twins: Use a DevOps environment or digital twin (via Arista ACT, vEOS, or cEOS) to simulate post-migration state, validate configurations, and refine runbooks before production deployment.

Part 4. Step-by-Step Migration Guide and Interoperability Gotchas

Core Migration Steps

1. Build the New Fabric: Deploy new Arista infrastructure in parallel. Use Zero Touch Provisioning (ZTP) and AVD for configuration.
2. Establish Inter-Domain Links: Create redundant L2/L3 links between Cisco and Arista domains. Use BGP for routing prefixes and trunk required VLANs.
3. Configuration Conversion and Standardization: Convert legacy Cisco configurations to EOS CLI or YAML models.
4. Traffic Steerage: Use traffic steering and Arista Maintenance Mode to gracefully redirect traffic.
5. Validation: Perform pre- and post-migration checks: NRFU, control plane, and data path integrity.

Critical Interoperability Gotchas

Part 5. Automation, Tools, and Configuration Conversion

Configuration Conversion

1. Extract legacy data from Cisco devices.
2. Export into AVD YAML framework for L3LS EVPN/VXLAN, tenant overlays, edge mapping.
3. Automate configuration generation via AVD, reducing human error.

Arista’s Automation Tools

Part 6. Cost, Licensing, and Long-Term Support

Licensing: Simplicity vs Complexity

• Cisco Smart Licensing: Complex; requires Smart/Virtual Accounts, PAK conversions, SLR management.
• Arista Simplified Licensing: Simple, reduces OPEX, less downtime for license issues.

Support and Training

• Cisco TAC: 24/7 support, large community, certified engineers.
• Arista TAC: Responsive, Day 2 support, formal training courses, Arista Community Central resources.

Router-switch.com Soft Promotion: Router-switch.com specializes in supplying both Cisco (Nexus) and Arista (7000 Series) hardware, including certified pre-owned options, helping enterprises optimize costs during migrations.

Part 7. Best Practices and Risk Mitigation

• Implement GitOps and CI pipelines for version control and change management.
• Leverage ACT to simulate traffic/failures before deployment.
• Use Maintenance Mode to drain traffic gracefully.
• Normalize proprietary Cisco features for interoperability.

Part 8. Summary

Migrating from Cisco to Arista transitions organizations from complex, proprietary ecosystems to simplified, automation-focused, high-performance environments. Proper planning, interoperability handling, and testing yield long-term benefits in operations, licensing, and network stability. For organizations looking to streamline this migration with trusted suppliers and access to both new and certified pre-owned Cisco and Arista hardware, Router-switch offers reliable sourcing, professional support, and competitive solutions to help ensure a smooth transition.

Common Questions About Cisco to Arista Migration

Q1. What is the latency difference between Arista and Cisco switches?

Arista specializes in ultra-low latency switches. 7150S series achieves sub-380ns port-to-port latency. Cisco offers high-performance Nexus switches, but Arista dominates HFT niches.

Q2. Which is better for hyperscale cloud data centers?

Arista excels in hyperscale cloud due to low latency, software-driven architecture, and unified CloudVision. Cisco competes via Secure AI Factory and 800 gig Nexus switches.

Q3. How does automation differ between Arista EOS and Cisco ACI?

Arista EOS uses API-driven automation (eAPI, AVD), Linux-based tools, and GitOps. Cisco ACI is policy-driven and integrates with Nexus Dashboard.

Q4. How complex is the configuration migration process?

Configuration migration is complex due to Cisco proprietary features (VTP, UDLD). Per-design migration with AVD YAML models is recommended for accuracy and reduced human error.

Q5. Does Arista support Cisco’s proprietary protocols?

No. VTP, UDLD, and other proprietary Cisco protocols are not supported. Manual conversion or disabling is required for interoperability.

Q6. Is Arista's licensing simpler than Cisco's?

Yes. Arista has a simplified structure, while Cisco requires extensive Smart/Virtual Account management, PAK conversion, and SLR.

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