Cisco OTV (or Overlay Transport Virtualisation) is a technology inside Cisco Nexus switches (7K) for extending VLANs across a routed network. You can read all about OTV here and here. This post consists of an example configuration for a lab where you have a single Nexus 7K and you want to get OTV over multicast running between VDCs and comes from my CCIE study notes for when I was practicing with OTV. I’ve heard some people have issues with getting the multicast configuration working, so I figured I would share mine here.

First off, to create the illusion of … Read more


Cisco has made it clear that there will be no validated design for a FlexPod with VMware NSX running as the virtual network and there will be no trifecta vendor support for the entire platform. This does not mean you’re completely barred from using it though. To be able to make use of the best of both worlds, I’ve been working to create a design that uses FlexPod as the rock solid foundation and offer the networking flexibility that VMware NSX offers. The goal is to not change the FlexPod design so that it will still be certified for support.… Read more


UCS is different then other server platforms, which sometimes makes simple maintenance tasks not as straightforward as you’d think. We had an truckload of CPU upgrades last week. A regular server admin would think; “Hey, I just take this old CPU out and put this new CPU in and bob’s my uncle!” – well, UCS might have a surprise for you.

One of my colleagues (a ‘traditional’ server guy) handled this replacement and was confronted with an error message when reinserting the blades: WILL_BOOT_FAULT (awesome description once again, Cisco). Considering the error message itself, they went looking for boot issues. … Read more


Cisco held a “UCS Grandslam” today, where they announced some amazing new UCS products and announced a few refreshers of the UCS family. I think “Grand Slam” is a baseball term (not american 😉 ), because there was a pretty cool presentation from the major league baseball on how they are using the Internet of Things (IoT) to further the multimedia experience of baseball.

On to the important stuff! Cisco is refreshing and expanding the UCS family with a few new awesome things:

  • UCS Mini. Smaller UCS Pod, with built-in Fabric Interconnects (check my review a while
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Cisco has released version 3.1 of its virtualised switch (available for download here). It comes with increased scalability and resiliency, but one very cool thing stood out for me: the Virtual Switch Update Manager or VSUM.

The VSUM is not the only cool improvement on the virtual switch, here’s an overview of changes:

  • Scale
    • Increased Scalability (Advanced Edition) – More than doubles the scale from the previous release. The virtual switch now supports 250 hosts/servers per switch with 10,000 ports per switch. In addition it supports 4094 active VLANs and 16 million VXLAN (6144 active VXLANs) per switch across
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As I’m writing this post, I am still high on the drug that is called a passing grade. After 10 months of studying the blueprint and putting in hundreds of hours reading through the configuration guides, building topologies (just to tear them down and start over when you’re done), one failed attempt in May, dreaming about all things Cisco UCS, Nexus (physical and virtual) and MDS..I can finally say that I got my CCIE on Datacenter: number 44460 (an easy one to remember too!).

Stating the obvious is usually not my thing, but this time I’ll make an exception: Preparation Read more


While troubleshooting VLAN connectivity on UCS in end-host mode with multiple uplinks, it is be good to know which uplink is the designated receiver (listener for broadcast and multicast) for which VLAN. This will be useful when you have L2 connectivity issues, where 1 or more VLANs are having issues going outside the Fabric Interconnects.

Considering the length of the command to find the designated receivers, I haven’t memorised the command itself, but the which command to find it:

UCS-FI-A(nxos)# which | inc vlandb
(2511) show platform software enm internal info vlandb { all | xlatetbl | id  }

After … Read more