300-635 · Question #66
Drag and drop the requirements from the left that are needed to leverage POAP in an Open Cisco NX-OS environment.
POAP (Power-On Auto Provisioning) in Open Cisco NX-OS Since the options field is empty in your question, I'll explain the core POAP requirements based on Cisco NX-OS documentation and exam objectives. --- Overall Goal POAP enables zero-touch provisioning - a Nexus switch boots…
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Explanation
POAP (Power-On Auto Provisioning) in Open Cisco NX-OS
Since the options field is empty in your question, I'll explain the core POAP requirements based on Cisco NX-OS documentation and exam objectives.
Overall Goal
POAP enables zero-touch provisioning - a Nexus switch boots with no startup config, automatically discovers a provisioning server, downloads a script, and self-configures without manual CLI intervention. This is critical for large-scale data center deployments.
Required Components
| Requirement | Why It's Needed |
|---|---|
| DHCP Server | The switch broadcasts a DHCP Discover on boot. The DHCP server returns an IP address and points to the TFTP/HTTP server via DHCP Option 150 (TFTP server) or Option 67 (boot filename). Without DHCP, POAP cannot bootstrap at all. |
| TFTP or HTTP Server | Hosts the POAP Python script, NX-OS software image, and config file. The switch fetches the script from this server using the path provided by DHCP. |
| POAP Python Script | The automation brain. It instructs the switch on what to download (image, config) and how to apply it. Open NX-OS exposes a Python interpreter, making this scripting possible. |
| NX-OS Software Image | The target OS image the script installs. Must be a compatible version for the hardware. |
| Switch Configuration File | The final startup-config applied after the image boots. Defines VLANs, interfaces, routing, etc. |
Step-by-Step Flow and Reasoning
1. Switch boots → no startup-config detected → POAP starts automatically
- NX-OS checks for a startup config on boot. If absent (new device or factory reset), POAP triggers. Skipping this: not possible to skip - it's automatic.
2. DHCP Discover is sent
- The switch needs Layer 3 reachability before it can contact any server. DHCP provides the IP and the TFTP server address in one response.
- If DHCP is missing: POAP times out and drops to manual config mode.
3. Script downloaded from TFTP/HTTP server
- The Python script is the decision engine. Without it, the switch has no instructions.
- If server is unreachable: POAP aborts. The script filename must match exactly what DHCP Option 67 specifies.
4. Script executes - downloads image and config
- The script uses NX-OS Python APIs to copy files, verify MD5 checksums, and stage the config.
- If script has errors: POAP fails mid-process, potentially leaving the switch in an inconsistent state.
5. Switch reloads with new image and applies config
- The final step completes provisioning. The switch comes up fully configured.
What Would Go Wrong If Steps Are Skipped
- No DHCP server: Switch cannot find the TFTP server → POAP never starts downloading
- No TFTP server / wrong path: Script fetch fails → no automation logic runs
- No Python script: Even with a reachable server, there's nothing to execute
- No image file: Switch remains on old/incompatible NX-OS
- No config file: Switch boots with empty config even after correct image is loaded
Memory Tip
Use the mnemonic "D-S-S-I-C":
DHCP → Server (TFTP) → Script (Python) → Image → Config
Each letter is a dependency on the previous one - no step can succeed without the one before it.
Key exam distinction: In an Open NX-OS environment specifically, the Python script requirement is enabled by the open programmability layer (Bash shell, Python interpreter, NX-OS APIs). On classic NX-OS, POAP also exists but the scripting environment is the differentiating feature of the Open variant.
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