From a network engineer to network engineers. No bullshit.

The Lab Setup

Alright, folks. We’re about to simulate a “baremetal” Kubernetes cluster. And by “baremetal,” I of course mean an Ubuntu VM running inside a hypervisor that’s itself virtualized. You get the idea. Here’s the master plan:

Now, because we’re doing this the right way:

1. We’ll emulate the whole thing right in PNETLAB.

2. We’re using a Leaf-Spine topology. Standard.

How to Deliver Traffic to a Service in a Data Center

Let’s Briefly Recap: What Are Data Center Networks?

For about two decades now, the entire networking engineering and architecture industry has shifted from so-called “classic three-tier architecture” (with access layer devices, aggregation layer devices, a core, and some external gateway) to Leaf-Spine networks (also known as Clos architecture).

Leaf-Spine—well, obviously, because there are leaves, spines, super-spines, and all that jazz. I think anyone who’s ever Googled or asked their senior (or junior, more up-to-date colleague) about “data center networks” has probably seen a diagram like this.

No preface, no chit-chat. Let’s go.

Let’s build a network without any hardware switches or routers.

So, we’ve got two client hosts and one Linux box. The hosts are in the same subnet. We need to make them talk to each other. Basically, we gotta turn that Linux into a dumb D-link switch. Easy peasy:

Alright, this is a piece of cake. Install bridge-utils, whip up a bridge, toss those interfaces into the bridge, don’t forget to bring it up, and boom—voilà!