Network Operations

Upgrading IOS on a Catalyst 3560 is not complicated, but the details matter: which file format you download, how much space is left in flash, and whether the boot variable points to the right image. A mistake in any of these leaves you with a switch that boots into the boot loader instead of IOS. There are two ways to do it: Method A: archive download-sw with a .tar file. The switch extracts the image, the web device manager files and sets the boot variable itself. Method B: manual upgrade with a .bin file. You copy the image, verify it, set boot system and reload. Lab note: I am upgrading my own Catalyst 3560 8-port PoE switch with both methods. Console outputs and timings from that lab will be added to this guide. ...

You inherit a switch, the documentation is gone, and nobody knows the enable password. Or a lab switch comes back from storage and the console asks for a password you never set. On a Cisco Catalyst 3560 you can recover from both without losing the configuration, as long as you have physical access and a console cable. This guide covers the two situations you will meet in practice: Method 1: keep the configuration. The switch boots without loading its startup configuration, you reset the passwords, and you put the original configuration back. Method 2: password recovery is disabled. Someone configured no service password-recovery. You can still get the switch back, but only by resetting it to factory defaults. Lab note: I am running these procedures on my own Catalyst 3560 8-port PoE switch. Console outputs from that lab will be added to this guide. ...

Sooner or later every network engineer sees it: after a reload, the switch does not come back. On the console there is only a switch: prompt. The IOS image is missing, corrupted, or the boot variable points to a file that does not exist. This is not a reason to replace the switch. The Catalyst 3560 boot loader has everything you need to get IOS running again, even when the image in flash is gone. This guide covers: ...

This guide covers the Cisco Nexus NX-OS software upgrade process in a practical, step-by-step manner — including rollback and recovery scenarios. The goal is to minimize service disruption and ensure the device can always be recovered in case of failure. Most upgrade failures are not caused by the upgrade itself — they are caused by skipping preparation steps. This guide treats preparation as seriously as execution. Cisco Nexus NX-OS Upgrade Process For out-of-band access during upgrade failures, see: The Backdoor of the Network: Next-Gen Console Server Architecture ...