Category: Data Center

One of my readers sent me an interesting reliability design question. It all started with a catastrophic WAN failure:

Once a particular volume of encrypted traffic was reached the data center WAN edge router crashed, and then the backup router took over, which also crashed. The traffic then failed over to the second DC, and you can guess what happened then...

Obviously they’re now trying to redesign the network to avoid such failures.

Gabi Gerber (the wonderful mastermind behind the Data Center Day event) is helping me bring my Designing Infrastructure for Private Clouds workshop (one of the best Interop 2015 workshops) to Switzerland.

This is the only cloud design workshop I’m running in Europe in 2015. If you’d like to attend it, this is your only chance – register NOW.

At least a dozen engineers sent me emails or tweets mentioning Project Calico in the last few weeks – obviously the project is getting some real traction, so it was high time to look at what it’s all about.

TL&DR: Project Calico is yet another virtual networking implementation that’s a perfect fit for a particular use case, but falters when encountering the morass of edge cases.

One of my readers wondered whether one still needs traditional firewalls in microsegmented environments like VMware NSX.

As always, it depends.

During the Cumulus Linux presentation Dinesh Dutt had at Data Center Fabrics webinar, someone asked an unexpected question: “Do you have In-Service Software Upgrade (ISSU) on Cumulus Linux” and we both went like “What? Why?”

Dinesh is an honest engineer and answered: “No, we don’t do it” with absolutely no hesitation, but we both kept wondering, “Why exactly would you want to do that?”

Packet Pushers podcast is a constant source of inspiration for my blog posts. Recently I stumbled upon Rob Sherwood’s explanation of how they package Big Cloud Fabric:

It’s a vertically integrated solution, from Switch Light OS to our SDN controller and Big Cloud Fabric application.

Really? What happened to openness and disaggregation?

I helped several customers design scale-out private or public cloud infrastructure. In every case, I tried to start with a reasonably small pod (based on what they’d consider acceptable loss unit – another great term I inherited from Chris Young), connected them to a shared L3 backbone (either within a data center or across multiple data centers), and then tried to address the inevitable desire for stretched layer-2 connectivity.

You’ll find a summary of these designs in my next ExpressExpress case study: Scale-Out Private Cloud Infrastructure, and if you need more details, I’m usually available for online consulting.

I was running the first part of the Data Center Fabrics Update webinar last week, mentioned that Brocade VDX 6740 supports Flex ports (a port you can use as Fibre Channel or 10GE port), and someone immediately wrote a comment saying “so does VDX 6940”. I was almost sure Flex ports aren’t available on VDX 6940 yet, and as always turned to vendor documentation to figure it out.

As expected, the data sheet is a bit vague, somewhat reflecting reality, but also veering into the realm of futures instead of features. Here’s what they say:

One of my readers sent me this question:

After reading this blog post and a lot of blog posts about zero trust mode versus security zones, what do you think about replacing L3 Data Center core switches by High Speed Next Generation Firewalls?

Long story short: just because someone writes about an idea doesn’t mean it makes sense. Some things are better left in PowerPoint.

One of the responses I got on my “What is Layer-2” post was

Ivan, are you saying to use L3 switches everywhere with /31 on the switch ports and the servers/workstation?

While that solution would work (and I know a few people who are using it with reasonable success), it’s nothing more than creative use of existing routing paradigms; we need something better.