Daniel Dib started writing a series of blog posts describing Cisco vPC in VXLAN/EVPN Networks. The first one covers the anycast VTEP, the second one the vPC configuration.

Let’s hope he will keep them coming and link them together so it will be easy to find the whole series after stumbling on one of the posts ;)

If you insist on building your network with EBGP as a better IGP, make sure your implementation supports running IPv4 and IPv6 address families over EBGP sessions established between IPv6 link-local addresses (the functionality lovingly called unnumbered EBGP sessions).

Want to practice that neat trick? Check out the EBGP Sessions over IPv6 LLA Interfaces lab exercise.

Béla Várkonyi is working on an interesting challenge: building ground-to-airplane(s) networks providing multilink mobility. Due to its relative simplicity, he claims LISP works much better than BGP in that environment.

In some newer routers BGP would not be such a big bottleneck, but you need a lot of knob turning in BGP to get it right, while in LISP it is quite simple.

If you have many thousands concurrent airplanes with multi-link and max. 16 subnets with different routing policies on each, and the radio links are going up and down, then you have a large number of mobility events.

When designing the netlab VRF configuration module, I tried to make it as flexible as possible while using the minimum number of awkward nerd knobs. As is often the case¹, the results could be hard to grasp, so let’s walk through the various scenarios of using global and node VRFs.

netlab allows you to define a VRF in the lab topology vrfs dictionary (global VRF) or in a node vrfs dictionary (node VRF). In most cases, you’d define a few global VRFs and move on.

You probably know I hate posting links to walled gardens or sites that try really hard to make you sign up. Sometimes, I have to make an exception: Roman Pomazanov wrote a great (and humorous) article comparing how easy it is to set up simple labs with GNS3, containerlab, and netlab.

Daniel left a very relevant comment on my Data Center Fabric Designs: Size Matters blog post, describing how everyone rushes to sell the newest gizmos and technologies to the unsuspecting (and sometimes too-awed) users¹:

Absolutely right. I’m working at an MSP, and we do a lot of project work for enterprises with between 500 and 2000 people. That means the IT department is not that big; it’s usually just a cost center for them.

One of my readers sent me an interesting update on the post-QUIC round of NBAR whack-a-mole (TL&DR: everything is better with Bluetooth AI):

So far, so good. However, whenever there’s a change, there’s an opportunity for marketing FUD, coming from the usual direction.

On April 22nd, I had an Intro to netlab presentation at the wonderful RIPE SEE meeting in Athens.

You can download the presentation or watch it on YouTube. Enjoy ;)

As a response to my LISP vs EVPN: Mobility in Campus Networks blog post, Route Abel provided interesting real-life details of a large-scale campus wireless testing using EVPN and VXLAN tunnels to a central aggregation point (slightly edited):

I was arguing for VxLAN EVPN with some of my peers, but I had no direct hands-on knowledge of how it would actually perform and very limited ability to lab it on hardware. My client was considering deploying Campus VxLAN, and they have one of the largest campuses in North America.

Another lovely must-read rant from the cranky security professional.

TL&DR: Data protection requirements like PCI-DSS aren’t there to make companies more secure but to make it too expensive for them to hoard excessive customer data (see also: GDPR).

TL&DR: FRRouting advertises the IP prefix on the lo loopback interface with zero cost.

Let’s start with the background story. When we added FRRouting containers support to netlab, someone decided to use lo0 as the loopback interface name. That device doesn’t exist in a typical Linux container, but it’s not hard to add it:

$ ip link add lo0 type dummy
$ ip link set dev lo0 up

One of my friends is running a large IPv6 network and has already experienced a shortage of IPv6 neighbor cache on some of his switches. Digging deeper into the root causes, he discovered:

In my larger environments, I see significant neighbor table cache entries, especially on network segments with hosts that make many long-term connections. These hosts have 10 to 20 addresses that maintain state over days or weeks to accomplish their processes.

What’s going on? A perfect storm of numerous unrelated annoyances:

Lasse Haugen had enough of the never-ending “we can’t possibly deploy IPv6” excuses and decided to start the IPv6 Shame-as-a-Service website, documenting top websites that still don’t offer IPv6 connectivity.

His list includes well-known entries like twitter.com, azure.com, and github.com plus a few unexpected ones. I find cloudflare.net not having an AAAA DNS record truly hilarious. Someone within the company that flawlessly provided my website with IPv6 connectivity for years obviously still has some reservations about their own dogfood ;)

I decided not to get involved in the EVPN-versus-LISP debates anymore; I’d written everything I had to say about LISP. However, I still get annoyed when experienced networking engineers fall for marketing gimmicks disguised as technical arguments. Here’s a recent one:

Dmitry Perets wrote an excellent description of how typical firewall cluster solutions implement control-plane high availability, in particular, the routing protocol Graceful Restart feature (slightly edited):

Most of the HA clustering solutions for stateful firewalls that I know implement a single-brain model, where the entire cluster is seen by the outside network as a single node. The node that is currently primary runs the control plane (hence, I call it single-brain). Sessions and the forwarding plane are synchronized between the nodes.