What Is POAP and Why Aren’t You Using It?

Peter Welcher
Architect, Operations Technical Advisor

20140303-fig01I get the strangest looks when I talk about POAP and ask people “Why Aren’t You Using It?” Admittedly, it doesn’t help that I like to pronounce acronyms like words, and POAP comes out sounding like “Pope” or perhaps “Poe-App”. Perhaps it will help if I mention that POAP is the Nexus equivalent of Auto-Install for Cisco routers. I suspect that aside from not being aware of POAP, a lot of people haven’t looked into what POAP can do for them. As with Auto-Install, you might have looked and found that it seemed complex. Yes, it’s easy enough to paste in the configuration from the CLI, one less thing to troubleshoot.

Why Would You POAP?

Plug in a new Nexus switch and it will automatically get upgraded to the latest code and configured from a central server. Which means you can be off doing useful work instead of waiting through all that. Also known as “more productive”.

DFA (Dynamic Fabric Automation) can leverage POAP in building the Spine-Leaf topology. It’s not clear whether ACI will as well. The N9K hardware base NX-OS apparently supports it, and I would be surprised if ACI doesn’t use POAP to form the infrastructure.

Newer versions of NX-OS support POAP from USB, where everything is done off a USB you plugged in, provided you put the necessary files on the USB with the right filenames.

POAP can also be used for fast reconfiguration of your entire infrastructure!

How to POAP

Basic information about POAP can be found here and here.

I’ll summarize for you. Here’s what happens:

  • Your freshly-installed Nexus boots up, discovers it has no configuration, and puts itself into POAP mode.
  • (Newer versions) Check for USB containing what’s needed.
  • It does DHCP, finds a DHCP server, and is told its interface IP address, gateway, and DNS server IP address(es). It also receives the IP address of either a TFTP server or the URL of an HTTP server.
  • It then downloads a configuration script to download and install the appropriate NX-OS software and configuration file.
  • The NX-OS image is downloaded if not already present. It will be used after the next reboot.
  • The downloaded configuration is stored as the startup configuration for use after the next reboot.
  • You can see error messages in syslog, on the console, and critical errors are logged to bootflash.
  • The switch reboots (or you reboot it) and the new image and configuration take effect. The running configuration is then saved as the startup configuration.

The DHCP address is only used while POAP is in control.

For details of these steps and a flowchart, follow the link above. See the link for Caveats as well.

Cisco provides Python and TCL scripts you can customize. Support varies with the hardware platform. I finally found the scripts in the Software Download areas for the products, which is not where I’d have expected to find them. You have to have a valid support contract to even look at the scripts, which is more than a bit annoying. My consulting customers generally do things like upgrades, so I rarely jump through the hoops of getting their support numbers added to my Cisco ID. I get that one shouldn’t be able to download the image without support, vendors have a right to make money. But the python or TCL script, that’s a bit ridiculous. Make it unlocked/freely downloadable!

By the way, if you’re not a programmer, the Python or TCL should be fairly easy to modify. Over the years I’ve coded in a number of languages, and have frequently found that it helps to start with something that someone else already coded, alter it, test it, and you’ll (eventually) catch on.

Things to Be Thankful For

Cisco didn’t name this feature Power-On Operational Provisioning.  <grin>

Related Links

Hashtags: #POAP #ACI #DFA #automation

Twitter: @pjwelcher

Disclosure Statement

ccie_15years_med CiscoChampion200PX

4 responses to “What Is POAP and Why Aren’t You Using It?

  1. Bob: Whenever Cisco or another vendor changes the name of a feature, it’s usually one of two things: (1) new marketing person for the product imposing their imprint and/or (2) some features have been added and the vendor wants to “re-launch” the product or feature. For PoAP, it looks to me mostly like #2.

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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.


Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.


John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.