UC Corner: cEdge - Single Image Switch to Controller Mode

cEdge is a Cisco router acting as SD WAN Edge. Cisco's road map is to replace vEdge products with cEdge. cEdge can be on ISR, ASR and CSR, as well as their corresponding virtual variants (such as ISR 1000v, CSR 1000v, etc.)

When the above devices operating in "regular mode", it's called "Autonomous Mode", which is your good old IOS XE command system. When they operate in "SD WAN mode", it's called "Controller Mode", which is Viptela-like command system.

In pre-17.2 versions, you'll have to load different software on the router to support different modes. Since version 17.2.1r, one single image can support two different modes. Please see https://community.cisco.com/t5/networking-blogs/ios-xe-17-2-1r-single-again-and-ready-to-mingle/bc-p/4091398

I put CSR 1000v 17.2.1r in my GNS3 lab. It boots into autonomous mode by default. I tried to switch it to controller mode with no luck. I was referring to https://www.cisco.com/c/en/us/td/docs/routers/sdwan/configuration/sdwan-xe-gs-book/install-upgrade-17-2-later.html#d17982e2074a1635. Also https://codingpackets.com/blog/cisco-sdwan-self-hosted-lab-part-2/

I did quite a lot research. However, this version is too new to yield any helpful resource online. I finally figured it out. It's a documentation issue.

First, let's take a look at Cisco documentation below:

Per above documentation, the cfg file (in router bootflash:) will trigger the mode change. That is NOT TRUE! At least not in CRS 1000v 17.2.1r. The cfg file won't be used UNTIL the router is switched to controller mode.

To switch from autonomous mode to controller mode, you use CLI command "controller-mode enable". Router will warn you that all configuration will be lost. After conformation, router will reboot into controller mode.

The first sign of controller mode is - you'll be prompted to enter username/password, even if you don't have it set up previously. Default username/password is admin/admin, which aligns with Viptela defaults.