So, today’s article is on VLAN separation, the problems it solves, and the problems it sometimes creates. Not all networks are cut from the same cloth. Some are simple and some are complex. Some are physical and some are virtual. Some are clean while others are quite messy. The one thing that they all have in common is that Cisco UCS works with all of them. Continue reading
So, about 2 years ago I was with a customer who had opted to purchase UCS over their incumbent HP hardware for their private cloud build. As a first step, we upgraded the firmware on the UCS system. What I did not know at the time was that the mgmt0 cable plugged into the “B” Fabric Interconnect (FI) was showing link, but was not on the right vlan (or wasn’t passing traffic). When it came time in the upgrade to failover the management instance of UCSM to the “B side”, we lost access completely to UCS manager. This and other seemingly related events (but were actually totally unrelated in hindsight) led me to believe that UCSM had failed in some manner and started me down a multi-hour troubleshooting session that I really wished had never happened. I opened an enhancement request to allow UCSM to detect this situation in the future and move UCSM back to the originating FI if it is unable to find the default gateway. Had I known this trick that I am about to tell you concerning the UCS shells, I might have been smart enough to get out of my situation much faster. The sad thing is I actually did know this – it was just knowledge from so early on in my UCS learning curve that I didn’t fully absorb the importance of it. So, now is your chance to start absorbing…
So, way back in early 2009, Sean McGee and I decided to work over the weekend in San Jose to get more stick time with “Project California” as UCS was called then. We borrowed a system from someone, backed it up, and started discovering how UCS worked. We had no help locally since it was a weekend and one thing I wanted to know was how to erase the configuration and start over. We were still months away from documentation and the online help inside the pre-1.0 UCSM was very incomplete. We eventually did figure out how to erase the configuration and start over, but we had to stumble upon it. Resetting UCSM is a well-documented process now, but I thought I’d write this post to cut through the pre-requisites and making sure proper backups are done, etc. I just wanted to give you the commands to get the job done. You’re on your own to make sure you really want to do this.