Category: overlay networks

Do you ever feel like we don’t have enough overlay networking technologies? Don’t worry, there’s always another one, for example Overlay Multilink Network Interface (OMNI) with Asymmetric Extended Route Optimization (AERO) services. Want to know more? Fred Templin described it in a series of overview articles on APNIC blog.

I got this question from one of ipSpace.net subscribers:

My VP is not a fan of overlays and is determined to move away from our legacy implementation of OTV, VXLAN, and EVPN¹. We own and manage our optical network across all sites; however, it’s hard for me to picture a network design without overlays. He keeps asking why we need overlays when we own the optical network.

There are several reasons (apart from RFC 1925 Rule 6a) why you might want to add another layer of abstraction (that’s what overlay networks are in a nutshell) to your network.

One of ipSpace.net subscribers wanted to see a real-life examples in the Overlay Virtual Networking webinar:

I would be nice to have real world examples. The webinar lacks of contents about how to obtain a fully working L3 fabric overlay network, including gateways, vrfs, security zones, etc… I know there is not only one “design for all” but a few complete architectures from L2 to L7 will be appreciated over deep-dives about specific protocols or technologies.

Most ipSpace.net webinars are bits of a larger puzzle. In this particular case:

Boris Lazarov sent me an excellent question:

Does it make sense and are there any inherent problems from design perspective to use the underlay not only for transport of overlay packets, but also for some services. For example: VMWare cluster, vMotion, VXLAN traffic, and some basic infrastructure services that are prerequisite for the rest (DNS).

Before answering it, let’s define some terminology which will inevitably lead us to the it’s tunnels all the way down endstate.

Remember the claim that networking is becoming obsolete and that everyone else will simply bypass the networking teams (source)?

Good news for you – there are many fast growing overlay solutions that are adopted by apps and security teams and bypass the networking teams altogether.

That sounds awesome in a VC pitch deck. Let’s see how well that concept works out in reality using Docker Swarm as an example (Kubernetes is probably even worse).

This podcast introduction was written by Nick Buraglio, the host of today’s podcast.

As private overlays are becoming more and more prevalent and as SD-WAN systems and technologies advance, it remains critical that we continue to investigate how we think about internetworking. Even with platforms such as Slack Nebula, Zerotier, or the wireguard based TailScale becoming a mainstream staple of many businesses, the question of “what is next” is being asked by an ambitious group of researchers.

Found this “gem” describing the differences between layer-2 and layer-3 on an unnamed $vendor web site.

Layer 2 is mainly concerned with the local delivery of data frames between network devices on the same network or local area network (LAN).

So far so good…

I published a blog post describing how complex the underlay supporting VMware NSX still has to be (because someone keeps pretending a network is just a thick yellow cable), and the tweet announcing it admittedly looked like a clickbait.

[Blog] Do We Need Complex Data Center Switches for VMware NSX Underlay

Martin Casado quickly replied NO (probably before reading the whole article), starting a whole barrage of overlay-focused neteng-versus-devs fun.

I spent a lot of time during this summer figuring out the details of NSX-T, resulting in significantly updated and expanded VMware NSX Technical Deep Dive material… but before going into those details let’s do a brief walk down the memory lane ;)

You might remember a startup called Nicira that was acquired by VMware in mid-2012… supposedly resulting in the ever-continuing spat between Cisco and VMware (and maybe even triggering the creation of Cisco ACI).

One of my readers sent me a series of questions regarding a new cloud deployment where the cloud implementers want to run VXLAN and EVPN on the hypervisor hosts:

I am currently working on a leaf-and-spine VXLAN+ EVPN PoC. At the same time, the systems team in my company is working on building a Cloudstack platform and are insisting on using VXLAN on the compute node even to the point of using BGP for inter-VXLAN traffic on the nodes.

Using VXLAN (or GRE) encap/decap on the hypervisor hosts is nothing new. That’s how NSX and many OpenStack implementations work.

In Episode 69 of Software Gone Wild we discussed ways of increasing visibility into VXLAN transport fabric. Another thing we badly need is visibility into the virtual edge behavior, and to help you get there Iwan Rahabok created a set of vRealize dashboards that include the virtual edge networking components. Hope you’ll find them useful.

Running Linux containers on a single host is relatively easy. Building private multi-tenant networks across multiple hosts immediately creates the usual networking mess.

Fortunately the Socketplane team did a pretty good job; for more details watch the video from Docker Networking Fundamentals webinar or listen to the podcast I did with them a year ago.

After explaining the basics of Linux containers, Dinesh Dutt moved on to the basics of Docker networking, starting with an in-depth explanation of how a container communicates with other containers on the same host, with containers residing on other hosts, and the outside world.

Three years ago I was speaking with one of the attendees of my overlay virtual networking workshop @ Interop Las Vegas and he asked me how soon I thought the overlay virtual networking technologies would be accepted in the enterprise networks.

My response: “you might be surprised at the speed of the uptake.” Turns out, I was wrong (again). Today I’m surprised at the lack of that speed.

The featured webinar in May 2016 is the Overlay Virtual Networking webinar and in the featured videos (the ones marked with a star) you'll find introduction to overlay virtual networking and deep dive into flooding and MAC address learning in layer-2 overlay virtual networks.