Network Design and Architecture Questions
Designing networks at the topology level: data-center, campus, branch-office, and WAN architecture, MPLS and traffic engineering, QoS, redundancy and resilience, capacity and growth planning, and equipment selection. Covers building networks that scale, tolerate failure, and meet performance requirements, plus justifying design and vendor choices. The architecture layer above configuration.
Your company has a headquarters and ten branch offices across two countries. Requirements include voice and video, SaaS access, acceptable critical-app downtime under 5 minutes, and limited OPEX. Design a resilient WAN architecture and justify choosing MPLS, SD-WAN, or a hybrid approach. Include routing, QoS, security inspection, and failover behavior.
For a leaf-spine data center running EVPN-VXLAN with BGP underlay, describe possible failure modes such as single-leaf failure, spine failure, control-plane flap, and ARP or MAC learning inconsistencies. For each failure mode, outline detection methods and mitigation strategies, including protocol features to enable (for example BFD, graceful restart, or MAC learning tuning).
Describe the core differences between MPLS and SD-WAN as enterprise WAN solutions. For a company with many remote branches, heavy SaaS usage, and limited budget, state which solution you would recommend and justify your answer with considerations on cost, SLA, security, and operational complexity.
Design routing and security for a cross-region service mesh where services talk over mutual TLS and you need to enforce network-level segmentation in addition to application policies. Explain how you would combine network zones, firewall policies, and service mesh mTLS to prevent lateral movement while enabling service discovery and resilience.
Design an SD-WAN architecture for an enterprise under strict regulatory controls that require physical separation of regulated traffic, on-box in-line inspection at branches, full packet capture for audits, and strong encryption. Outline overlay design, key management, policy enforcement model, and how to meet performance SLAs for real-time traffic while meeting compliance.
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