Stop Writing CLI — Start Validating Design

The Project That Triggered This Post Recently, I was assigned to a mid-scale network migration spanning three data centers. The architecture was straightforward but labor-intensive: dozens of VRFs, hundreds of point-to-point BGP sessions in a BGP fabric, and a VMware NSX overlay. Despite this modern setup, I was asked to manually write all of the configuration changes as CLI. After coding over 6,000 lines of CLI that night, I paused to reflect: ...

November 18, 2025 · 3 min · Gary Wong

Tweaking the Cisco Nexus 9000 TCAM: A Real-World Fix and iCAM Insights

In a recent project, I had the opportunity to work with something “new” yet familiar. During a customer data center refresh project, one of the key tasks was upgrading their aging Nexus 5000 to the new Nexus 9000 series. The model in play? N93360YC-FX2, a powerhouse with enhanced capabilities — but with a few nuances. At first glance, porting over configurations from the N5K seemed straightforward. No FCoE, no zoning, no fancy storage integrations. ...

November 1, 2024 · 2 min · Gary Wong

Automating Cisco Device Upgrades with Ansible: A Playbook Journey

As networks scale and new software updates become available, keeping Cisco devices up to date is crucial for maintaining optimal performance, security, and functionality. However, manually upgrading multiple devices can be time-consuming and prone to errors. That’s where Ansible comes into play, allowing us to automate and streamline the entire upgrade process for Cisco IOS/IOS-XE devices. Over the past few weeks, I’ve been working on a series of Ansible playbooks to automate this task efficiently. ...

September 1, 2024 · 5 min · Gary Wong

Continue the Network Automation Journey Using AWX

I have been working on a project recently to assist a customer in upgrading thousands of devices in their network. Managing such a large-scale upgrade requires automation to ensure consistency, efficiency, and reduced manual intervention. For this project, AWX was selected as the automation UI platform, providing a powerful interface for managing Ansible playbooks, job templates, inventories, and credentials. What is AWX? AWX is the upstream open-source project for Red Hat Ansible Tower. It provides an intuitive web UI for: ...

May 1, 2024 · 4 min · Gary Wong

DHCP Relay in EVPN-VXLAN

In previous posts, I discussed the construction of an EVPN-VXLAN fabric using Cisco NDFC. A critical aspect often overlooked — and the focus of this post — is the transition from a traditional 3-tier data centre architecture to an EVPN-VXLAN setup. One notable challenge in this transition is the configuration of the DHCP relay. Why DHCP Relay Behaves Differently in EVPN-VXLAN Traditionally, DHCP relays are configured to identify the default gateway using link-selection (DHCP Option 82 sub-option 5), ensuring IP addresses are allocated from the correct scope. ...

December 1, 2023 · 4 min · Gary Wong