Description

This curriculum spans the design, deployment, and governance of segmented LAN architectures in enterprise application environments, comparable in scope to a multi-phase network modernization initiative involving cross-functional teams, hybrid infrastructure integration, and ongoing compliance alignment.

Module 1: Defining Network Boundaries and Application Scope

Determine which applications require LAN isolation based on data sensitivity, compliance mandates, and user access patterns.
Map inter-application dependencies to identify services that must communicate across LAN segments.
Decide whether to segment by functional domain (e.g., HR, Finance) or by technical tier (e.g., web, database).
Establish naming conventions for VLANs and subnets that align with organizational IT standards and support automation.
Document exceptions for legacy systems that cannot support modern segmentation due to hardcoded IP dependencies.
Coordinate with security teams to align LAN segmentation with firewall zone policies and intrusion detection rules.

Module 2: Designing VLAN and Subnet Architecture

Select subnet sizes using IP address forecasting for each application tier, factoring in growth and redundancy needs.
Implement VLAN trunking between switches while ensuring native VLANs are securely configured and unused.
Assign unique VLAN IDs per application environment (dev, test, prod) to prevent cross-environment leakage.
Design failover paths using HSRP or VRRP across Layer 3 boundaries without introducing asymmetric routing.
Integrate private IP addressing with RFC 1918 standards while avoiding overlap with cloud VPC CIDR blocks.
Validate routing table scalability by measuring the impact of inter-VLAN routes on core switch memory and CPU.

Module 3: Integrating Security Policies and Access Controls

Configure ACLs on Layer 3 switches to restrict traffic between application tiers based on least-privilege principles.
Enforce mutual TLS for service-to-service communication within the LAN where encryption-in-transit is mandated.
Implement port security on access switches to prevent unauthorized device attachment via end-user ports.
Coordinate with IAM teams to synchronize user VLAN assignment with directory service group memberships.
Deploy 802.1X authentication for wired endpoints and define fallback mechanisms for non-compliant devices.
Log and monitor all access control denials using SIEM integration to detect misconfigurations or probing attempts.

Module 4: Application Deployment and Network Integration

Automate VLAN provisioning during CI/CD pipeline execution using infrastructure-as-code templates and API-driven switches.
Assign static versus DHCP reservations for application servers based on configuration management requirements.
Validate DNS resolution across subnets to ensure service discovery functions in multi-tier deployments.
Test application startup sequences to confirm dependencies are reachable before service initialization.
Integrate health checks with network monitoring to trigger failover when critical LAN segments become unreachable.
Manage MTU consistency across application paths to prevent fragmentation in high-throughput data transfers.

Module 5: Monitoring, Logging, and Performance Tuning

Deploy NetFlow or sFlow collectors to baseline traffic patterns and detect anomalies in inter-application communication.
Configure SNMP traps on switches to alert on port flapping, duplex mismatches, or bandwidth thresholds.
Correlate application latency spikes with switch buffer utilization and QoS policy effectiveness.
Archive switch configurations regularly and integrate with version control for audit and rollback.
Use packet capture at strategic points to diagnose asymmetric routing or policy misapplication.
Optimize broadcast domain size by pruning unused VLANs from trunks and adjusting STP domains.

Module 6: High Availability and Disaster Recovery Planning

Design redundant switch topologies with MLAG or stacking to eliminate single points of failure in access layers.
Test VLAN extension across data centers using OTV or EVPN and evaluate convergence times during link loss.
Validate failover of default gateways using ICMP and application-level probes during simulated outages.
Replicate critical application data across LAN segments with synchronous versus asynchronous replication trade-offs.
Document recovery procedures for VLAN database corruption or switch firmware failures.
Conduct tabletop exercises to assess LAN recovery time objectives (RTO) under various outage scenarios.

Module 7: Governance, Change Management, and Compliance

Enforce change control for VLAN modifications using ticketing system integration and peer review requirements.
Conduct quarterly access reviews to deprovision orphaned VLANs and unused switch ports.
Map network segmentation to regulatory frameworks such as PCI DSS, HIPAA, or GDPR for audit readiness.
Standardize VLAN provisioning workflows across teams to reduce configuration drift and human error.
Archive network diagrams and update them automatically from configuration management databases.
Implement role-based access controls on switch management interfaces aligned with least-privilege policies.

Module 8: Hybrid and Cloud Integration Strategies

Extend on-premises VLANs to cloud environments using AWS Direct Connect or Azure ExpressRoute with VLAN tagging.
Translate on-premises VLAN policies into cloud security groups and network ACLs without over-permissioning.
Route traffic between cloud and on-premises application tiers using dynamic routing protocols like BGP.
Encrypt inter-site traffic using IPsec tunnels when extending LANs over public infrastructure.
Manage DNS and service discovery across hybrid environments to maintain application transparency.
Monitor latency and jitter on extended VLAN paths to ensure real-time applications remain functional.

Modular LAN in Application Development