Think again!

I recently had an attendee approach me at our <strong>wildly successful </strong><a href="http://blogs.egroup.jasonmangone.com/?p=2626">Charlotte UCS VMUG</a>, asking me if it was possible to skip the UCS 6100 series Fabric Interconnects and "direct connect" the UCS 2104 FEX modules (the embedded FEX modules in the 5108 Blade Chassis) to a Nexus 5000 series switch.

Something to the effect of:  ”Have you tried connecting 2104 FEXs to Nexus 5000s? Will they show up like 2248s or other FEX modules?”

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I'd never been asked this question before, and although I knew skipping the 6100s was a silly idea for a variety of reasons, the customer saw the 6100s as a political point of contention between their network teams and server teams, and really was curious about just ”direct connecting” (their words) the internal 2104 FEX modules (from the 5108 B-Series Blade enclosures) to the upstream 5000s. 

Since none of us around eGroup had even tried it in the lab, and at the expense of looking like a total noob (best way to learn right? ask the experts?), I reached out to several contacts at Cisco - who immediately provided great detail and some direct feedback...

Best answer I had initially received (Cisco DC person) was “<em>I think that it probably won’t work because FEX/IO Modules get their firmware/software load from the operating system of the 6100 or Nexus 5000. I would guess that the OS on the 5000 doesn’t have the firmware for the 2104.  have no idea what would happen . . . but even if it would work, it would make management of the blades completely dependent on plugging the dongle into the front of each blade . . .</em> ”

That made a lot of sense to me (the bit about the 5000s not having the downloadable firmware for the 2104 FEX module) – as well as having to manage the blades “manually”

Again, since we'd never actually tried to do this, I got to thinking that the attendee might be on to something with the notion that "Hey - these are just servers, right? Using standard hardware....?" 

I suppose I never considered the Service Profile being a critical <strong>*dependency*</strong> for the blades to actually function since we all were thinking they are (more or less) servers with (more or less) standard hardware, so we weren’t sure if the SP was a critical dependency <strong>*required*</strong> for operation, or simply a management overlay that can be <strong>*imprinted*</strong> onto the blade via the Fabric Interconnect devices (basically an abstraction layer)

Ultimately, I received the clincher from <a href="http://bradhedlund.com/">Brad Hedlund</a> (Thanks Brad!) who provided this tidbit – “<em>You can’t power on a blade without a Service Profile, even for simple standalone servers booting from local disk.</em>”

Guess that pretty much means the 6100s are a “must-have” –

HTH for those of you out there who have questions like this!
