Category: data center

Designing Active-Active and Disaster Recovery Data Centers

A year ago I was a firm believer in the unlimited powers of Software-Defined Data Centers and their ability to simplify workload migrations. After all, if you can use an API to create any data center object, what’s stopping you from moving the workload running in a data center to another location.

As always, there’s a huge difference between theory and reality.

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What Happens When a Data Center Fabric Switch Fails?

I got into an interesting discussion with a fellow networking engineer trying to understand the impact of a switch failure in a L2/L3 data center fabric (anything from Avaya’s fabric or Brocade’s VCS Fabric to Cisco’s FabricPath, ACI or Juniper’s QFabric) on MAC and ARP tables.

Here’s my take on the problem – have I missed anything?

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Cumulus Linux Base Technologies

Dinesh Dutt started his part of the Data Center Fabrics Update webinar with “what is Cumulus Linux all about” and “what data center architectures does it support” and then quickly jumped into details about the base technologies used by Cumulus Linux: MLAG and IP routing.

Not surprisingly, the MLAG part generated tons of questions, and Dinesh answered all of them, even when he had to say “We don’t do that.”

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VXLAN Hardware Gateway Overview

One of my readers stumbled upon blog post from 2011 explaining the potential implementations of VXLAN hardware gateways, and asked me if that information is still relevant.

I knew that I’d included tons of information in the Data Center Fabrics and VXLAN Deep Dive webinars, but couldn’t find anything on the web, so I decided to fix that in 2015.

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How Complex Is Your Data Center?

Sometimes it seems like the networking vendors try to (A) create solutions in search of problems, (B) boil the ocean, (C) solve the scalability problems of Google or Amazon instead of focusing on real-life scenarios or (D) all of the above.

Bryan Stiekes from HP decided to do a step in the right direction: let’s ask the customers how complex their data centers really are. He created a data center complexity survey and promised to share the results with me (and you), so please do spend a few minutes of your time filling it in. Thank you!

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Private and Public Clouds, and the Mistakes You Can Make

A few days ago I had a nice chat with Christoph Jaggi about private and public clouds, and the mistakes you can make when building a private cloud – the topics we’ll be discussing in the Designing Infrastructure for Private Clouds workshop @ Data Center Day in Berne in mid-September.

The German version of our talk has been published on Inside-IT; those of you not fluent in German will find the English version below.

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Don’t Optimize the Last 5%

Robin Harris described an interesting problem in his latest blog post: while you can reduce the storage access time from milliseconds to microseconds, the whole software stack riding on top still takes over 100 milliseconds to respond. Sometimes we’re optimizing the wrong part of the stack.

Any resemblance to SDN in enterprises or the magical cost-reduction properties of multi-vendor data center fabrics is obviously purely coincidental.

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Layer-3-Only Data Center Networks with Cumulus Linux on Software Gone Wild

With the advent of layer-3 leaf-and-spine data center fabrics, it became (almost) possible to build pure layer-3-only data center networks… if only the networking vendors would do the very last step and make every server-to-ToR interface a layer-3 interface. Cumulus decided to do just that.

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Can You Avoid Networking Software Bugs?

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.

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