Category: Design

Here’s an interesting story I got from one of my friends:

• A large organization used a disaster recovery strategy based on stretched IP subnets and restarting workloads with unchanged IP addresses in a secondary data center;
• Once they experienced a WAN connectivity failure in the primary data center and their disaster recovery plan kicked in.

However, while they were busy restarting the workloads in the secondary data center, and managed to get most of them up and running, the DCI link unexpectedly came back to life.

A month ago I published the video where I described the idea that “two switches is all you need in a medium-sized data center”. Now let’s dig into the details: the first step you have to take to optimize your data center infrastructure is to virtualize all servers.

For even more details, watch the Designing Private Cloud Infrastructure webinar, or register for the Building Next-Generation Data Center course.

I’ve been telling you to build small-to-midsized data center with two switches for years ;) A few weeks ago I’ve turned the presentation I had on that topic into a webinar and the first video from that webinar (now part of Designing Private Cloud Infrastructure) is already public.

One of the comments added to my Using BGP in Data Centers blog post said:

With symmetric fabric… does it make sense for a node to know every bit of fabric info or is reachability information sufficient?

Let’s ignore for the moment that large non-redundant layer-3 fabrics where BGP-in-Data-Center movement started don’t need more than endpoint reachability information, and focus on a bigger issue: is knowledge of network topology (as provided by OSPF and not by BGP) beneficial?

While the large data centers increasingly use BGP as the routing protocol within their fabrics, the enterprise engineers tend to shy away from that idea because they think BGP is too complex/scary/hard-to-configure/obsolete/unknown/whatever.

It’s time to fix that.

Nuno wrote an interesting comment to my Stretched Firewalls across L3 DCI blog post:

You're an old school, disciplined networking leader that architects networks based on rock-solid, time-tested designs. But it seems that the prevailing fashion in network design and availability go against your traditional design principles: inter-site firewall clustering, inter-site vMotion, DCI, etc.

Not so fast, my young padawan.

Let’s define prevailing fashion first. You might define it as Kool-Aid id peddled by snake oil salesmen or cool network designs by people who know what they’re doing. If we stick with the first definition, you’re absolutely right.

I was asked to present a data-center-related talk last week and decided to focus on one of my favorite topics: because most people don’t have more than a few hundred servers in their data center, they don’t need more than two switches (or a rack of servers).

Not surprisingly, an equipment reseller sitting in the room was not amused.

The video and the slide deck are already online, but there’s a minor challenge: the whole event was in Slovenian ;) However, I plan to record the same topic in English once my SDN travels stop.

During one of my SDN workshops, an attendees asked me “How do you build carrier-grade (5 nines) cloud infrastructure with VMware NSX?”

Short answer: You don’t… and it’s a wrong question anyway.

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.

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!