This is the complete Cisco Nexus Interview Preparation Guide
A deep-dive study guide covering the entire Nexus product family, VXLAN/EVPN, vPC, BGP EVPN, Clos Fabric architecture, NX-OS configurations, and interview tips. Originally compiled from Cisco official documentation and technical resources.
Table of Contents
- Cisco Nexus Product Family Overview
- Nexus Architecture Deep Dive
- Layer 2 Technologies
- Layer 3 Technologies
- NX-OS vs IOS Differences
- Nexus vs Catalyst Family Comparison
- VXLAN Fundamentals (For Legacy Engineers)
- BGP EVPN Deep Dive
- VXLAN Fabric Operations
- VXLAN Configuration Examples
- Cisco Nexus Dashboard and NDFC
- VXLAN vs Legacy Networks
- Clos Fabric Architecture
- Interview Tips and Common Questions
- EVPN Comprehensive Guide
- Stacking vs VPC — Complete Comparison
Part 1: Cisco Nexus Product Family Overview
The Nexus Family at a Glance
The Cisco Nexus family is purpose-built for data center environments. Unlike Catalyst switches (campus/enterprise), Nexus switches run NX-OS and are optimized for:
- High-density 10/25/40/50/100/200/400 GbE
- Low-latency forwarding
- VXLAN/EVPN overlay fabrics
- ACI (Application Centric Infrastructure) mode
- Programmability (NX-API, OpenConfig, gRPC)
Current Nexus Switch Series
| Series | Role | Key Features | Status |
|---|---|---|---|
| Nexus 9000 | Spine/Leaf (Flagship) | NX-OS + ACI mode, VXLAN/EVPN, Cloud Scale ASIC | Current |
| Nexus 7000/7700 | Core/Aggregation | VDC, OTV, FabricPath, MPLS | End-of-Sale |
| Nexus 5000/5600 | Access/Aggregation | Unified fabric (LAN+SAN), FCoE | End-of-Sale |
| Nexus 3000 | Top-of-Rack / HPC | Ultra-low latency (~1μs), L3 wire speed | Current |
| Nexus 1000V | Virtual Switch | Runs inside VMware ESXi hypervisor | End-of-Life |
Nexus 9300 ASIC Generations
| ASIC | Generation | Key Feature |
|---|---|---|
| -EX | 1st gen | 2600 Mpps, VXLAN/EVPN support |
| -FX / -FX2 / -FX3 | 2nd-4th gen | MACsec, enhanced buffer, cost-effective |
| -GX / -GX2 | 5th-6th gen | 400G native, deepest buffers, highest density |
💡 Interview Tip: The differences between ASIC generations come down to the number of slices, forwarding TCAMs, and flex tiles each ASIC supports.
Key Topics Covered in the Full Guide
VXLAN/EVPN Fundamentals
- Why VXLAN? Overcoming the 4096 VLAN limit with 16 million VNIs
- VTEP (Virtual Tunnel Endpoint) architecture
- BGP EVPN as the control plane (Route Types 1-5)
- Underlay vs Overlay network design
- BUM traffic handling (Ingress Replication vs Multicast)
vPC (Virtual Port Channel)
- Peer link, peer keepalive, orphan ports
- vPC+ for FabricPath environments
- vPC with VXLAN EVPN (distributed anycast gateway)
Clos/Leaf-Spine Architecture
- Why Clos? Predictable latency, equal-cost paths
- Spine-Leaf vs traditional 3-tier
- Scaling considerations and oversubscription ratios
NX-OS vs IOS
- Feature activation model (feature bgp, feature ospf)
- VDC (Virtual Device Contexts) for Nexus 7000
- NX-API and programmability advantages
- Process restart, ISSU, and high availability
Access the Complete 3500+ Line Guide
The full guide includes 16 parts with detailed configurations, comparison tables, interview questions with model answers, and an interactive HTML version.