Category: Data Center

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.

I was really excited when Juniper announced Junos Fusion. I hoped for QFabric Done Right, but after watching the NFD10 video describing the architecture, I was disappointed: they reinvented Fabric Extenders.

The blog post was slightly updated on November 14th 2015 based on feedback received from Juniper engineers.

Last year I claimed that you don’t need more than two switches in your data center (I’ll run a presentation on the same topic in a few days), but focused exclusively on the networking side of the equation.

Iwan Rahabok recently published a great blog post describing the compute- and storage parts of it. His conclusion: 1000 VM per rack is perfectly realistic.

One of the reasons I started creating ipSpace.net webinars was to help networking engineers grasp the basics of adjacent technologies like virtualization and storage. Based on feedback from an attendee of my Introduction to Virtual Networking webinar it works:

I am completely on the Network side of the house and understand what I need to build for Storage/Data replication, but I really never thoroughly understood why. This allowed me to have a coherent discussion with my counterparts in DB and Storage and some of the pitfalls that can occur if we try to cowboy the network design.

Recommendation: if you have a similar problem, start with Introduction to Virtual Networking and continue with Data Center 3.0 webinar.

I got this question from one of my readers (and based on these comments he’s not the only one facing this challenge):

I was wondering if you can do a blog post on Cisco's new ASA 5585-X clustering. My company recently purchased a few of these with the intent to run their cross data center active/active firewalls but found out we cannot do this without OTV or a layer 2 DCI.

A while ago I expressed my opinion about these ideas, but it seems some people still don’t get it. However, a picture is worth a thousand words, so maybe this will work:

Many vendors talk about network automation these days, and almost all of them gloss over an important detail: automation works best when you manage to simplify things to the bare minimum needed to get the job done.

One of the vendors that focus on simplifying the network device configuration is Cumulus Linux.

Another week, another ExpertExpress session, as is often the case focusing on two data centers with stretched VLANs spanning both of them. However, this one was particularly irksome, as the customer ran a firewall cluster stretched across two locations.

I gave the customer engineers my usual recommendations:

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.

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?

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.”