Technology Short Take #19

Welcome to Technology Short Take #19, the first Technology Short Take for 2012. Here’s this year’s first collection of links, articles, and thoughts regarding virtualization, storage, networking, and other data center technology-related topics. I hope you find something useful!


  • While configuration limits aren’t the most exciting reading, they are important from time to time. Here’s some configuration limits for the UCS 6100 and 6200 series.
  • Understanding the differences—both positive and negative—between the various approaches to solving a particular challenge is a key skill. That’s why I like this article on HP Flex-10 versus NIOC for VDI. The author (Dwayne) weighs the pros and cons of both approaches in helping to shape network traffic for VDI deployments using 10Gb Ethernet.
  • It would appear that my recent VXLAN and OTV connectivity posts (incorrect VXLAN post here, corrected VXLAN post here, and OTV/VXLAN post here) sparked a discussion about whether we really need to concern ourselves with traffic trombones. On one side we have Brad Hedlund speculating that the network should be treated like a large virtual I/O fabric; on the other side we have Greg Ferro countering that we do need to be concerned about the topology of the network. I can see both sides of the argument, but at this stage of the game, I’m inclined to agree more with Greg. In the future (it’s unclear how far in the future) I think that Brad’s points will be more valid, but not right now.
  • This post by Ivan Pepelnjak on VXLAN, IP multicast, OpenFlow, and control planes highlights some of the current limitations with VXLAN and thus reinforces why I think that Brad’s arguments are a bit ahead of their time.
  • A few folks had some write-ups on Embrane Heleos: Greg Ferro, Jason Edelman, Brad Hedlund, Brad Casemore, and Ivan Pepelnjak. My question (and this is spurred in part by some comments by Brad Casemore): is this another Cisco spin-in move?

Servers/Operating Systems/Applications



And that it’s for this time around; as always, I hope you’ve found something useful here. Courteous comments are always welcome; feel free to speak up below.

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  1. Kyle Mestery’s avatar

    Thanks for the mention in your Short Takes Scott! Let me know if there is any specific topics with regards to Open Source cloud and virtualization technology you would like me to talk about.

  2. Brad Hedlund’s avatar

    Hi Scott,
    Wow. Thanks for all the links! By the way, I agree with your assessment of the VXLAN posts. I wrote that piece knowing full well that it’s not ready for main stream acceptance, yet. That was the fun in writing. :-)


  3. vmjfk’s avatar

    Helios…”is this another Cisco spin-in move?”. I don’t think so, though I am not certain. Helios is making elastic network services (FW, tunnel, etc.) that allow service providers to allocate these services on demand without having to purchase large boxes up front. No upfront cost means no underutilized hardware lying about that has to be paid for even though not used. I don’t think Cisco would want this, other than to bury it. JMHO

  4. Mirek Burnejko’s avatar

    Great list as always Scott.

  5. Dan’s avatar

    Anyone else running into this issue?
    Very briefly mentioned here:

    I had a customer run into this, Spanning Tree got disabled on a few VLANs, and they had a loop created somewhere that brought down the entire 5596 pair.

    They had something like 300 VLANs being presented to every VM host and with the use of numerous FEX modules (4 uplinks, 16 downlinks per FEX) and maxed out the ~ 32K limit on their switches.


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