“Enforcing Zero Trust firewall rules on legacy application clusters without flow visibility will cause outages. vRealize Network Insight maps every active TCP port before you write a single rule.”

During an IBM Cloud SDDC migration for a financial client at IBM, legacy banking applications lacked accurate network architecture documentation.

Applying default-deny Distributed Firewall policies without understanding application traffic flows would have crashed critical transaction processing.

Architecture: IPFIX Flow Ingestion & Automated Rule Modeling

We deployed vRealize Network Insight (vRNI) collectors across physical switches and ESXi hosts.

1. IPFIX Flow Analysis: vRNI ingested NetFlow / IPFIX telemetry across 1,500 Virtual Machines for 30 days.
2. Automated Security Group Recommendation: Analyzed active communication pairs (e.g. App-Tier to DB-Tier on port 1521) and automatically generated recommended NSX Distributed Firewall rules.
3. Latency Troubleshooting: Identified high vNIC-to-vNIC latency spikes caused by physical switch port buffer overruns.

[!TIP] Export vRNI recommended firewall rules in XML format and import them directly into NSX Manager to eliminate manual policy entry errors.

# # vRNI Search Query to Audit Unmapped Cross-VLAN Flows
flows where src vnet = 'Prod-App-VLAN' and dst vnet = 'Prod-DB-VLAN' and port != 1521

The Verdict

Key Takeaway

Audit Active Network Flows with vRNI Telemetry Before Enforcing Zero Trust Firewall Rules.

Using vRealize Network Insight (vRNI) maps 100% of legacy application dependencies, guaranteeing zero downtime during Zero Trust microsegmentation rollouts.