Kubernetes services are like networking standards: there are so many to choose from. In his brief introduction to Kubernetes service types, Stuart Charlton listed six of them, and I’m positive there are more. That’s what you get when you’re trying to reinvent every network load balancing method known to mankind ;)

While ranting about Linux data plane configuration, I mentioned an interesting solution: Cumulus Linux Network Command Line Utility (NCLU), an attempt to make Linux networking more palatable to more traditional networking engineers.

NCLU is a simple wrapper around ifupdown2 and frr packages. You can execute net add and net del commands to set or remove configuration parameters¹, and NCLU translates those commands into changes to corresponding configuration files.

In the previous MLAG Deep Dive blog posts, we discussed the innards of a standalone MLAG cluster. Now let’s see what happens when we connect such a cluster to a VXLAN fabric – we’ll use our standard MLAG topology and add a VXLAN transport underlay to it with another switch connected to the other end of the underlay network.

Jordi left an interesting comment to my EVPN/VXLAN or Bridged Data Center Fabrics blog post discussing the viability of using VXLAN and EVPN in times when the equipment lead times can exceed 12 months. Here it is:

Interesting article Ivan. Another major problem I see for EPVN, is the incompatibility between vendors, even though it is an open standard. With today’s crazy switch delivery times, we want a multi-vendor solution like BGP or LACP, but EVPN (due to vendors) isn’t ready for a multi-vendor production network fabric.

netlab release 1.3 introduced support for VXLAN transport with static ingress replication. Time to check how easy it is to replace a VLAN trunk with VXLAN transport. We’ll use the lab topology from the VLAN trunking example, replace the VLAN trunk between S1 and S2 with an IP underlay network, and transport Ethernet frames across that network with VXLAN.

Charity Majors published another masterpiece: The Hierarchy Is Bullshit (And Bad For Business).

I doubt that anyone who would need this particular bit of advice would read or follow it, but (as they say) hope springs eternal.

One of the overused buzzwords of the cloudy days is the Cloud-Native Environment. What should that mean and why could that be better than what we’ve been doing decades ago? Matthias Luft and Florian Barth tried to answer that question in the Introduction to Cloud Computing webinar.

Here’s an interesting question randomly appearing in my Twitter feed:

If you had a greenfield network, would you choose SR-MPLS, or SRv6? And why?

TL&DR: SR-MPLS, assuming you’re building a network providing end-to-end connectivity between hardware edge devices.

Now for the why part of the question:

I spent a rainy day implementing VLANs, VRFs, and VXLAN on Cumulus Linux VX and came to “appreciate” the beauties of Linux networking configuration.

TL&DR: It sucks

There are two major ways of configuring data plane constructs (interfaces, port channels, VLANs, VRFs) on Linux:

An attendee in the Building Next-Generation Data Center online course sent me an interesting dilemma:

Some customers don’t like EVPN because of complexity (it is required knowledge BGP, symmetric/asymmetric IRB, ARP suppression, VRF, RT/RD, etc). They agree, that EVPN gives more stability and broadcast traffic optimization, but still, it will not save DC from broadcast storms, because protections methods are the same for both solutions (minimize L2 segments, storm-control).

We’ll deal with the unnecessary EVPN-induced complexity some other time, today let’s start with a few intro-level details.

netlab release 1.3.1 contains major additions to FRR and Cumulus Linux, and new BGP features:

• VXLAN, VLANs, VRFs, and EVPN implemented on FRR and Cumulus Linux
• BGP local-as implemented in the BGP configuration module and supported on Arista EOS, Cisco IOS, Dell OS10, FRR, and Nokia SR Linux.
• Configurable BGP transport sessions
• Configurable default BGP address families supported on Arista EOS, Cisco IOS, Cumulus Linux, FRR, and Nokia SR Linux.

Here are some of the other goodies included in this release:

The last video in the 2-hour-long Network Addressing part of How Networks Really Work discusses Network Address Translation.

After watching it, you might want to spend some extra quality time (with a bit of soap opera vibe) enjoying the recent ‌Dual ISP deployment operational issues and uncertainties thread on the v6ops mailing list with a “surprising” result: NPTv6 or NAT66 is the least horrible way to do it.

I keep hearing numerous variations of the following argument from people believing in the unlimited powers of multi-cloud¹ (deploying your workloads in multiple public cloud providers):

We don’t install all our servers in the same DC. But would you trust one Cloud Server Provider with all your applications? That’s why you should use multi-cloud.

I’ve been hearing similar arguments for at least 30 years, including:

Early bridges implemented a single bridging domain across all ports. Within a few years, we got multiple bridging domains within a single device (including bridging implementation in Cisco IOS). The capability to have multiple bridging domains stretched across several devices was still missing… until the modern-day Pandora opened the VLAN box and forever swamped us in the complexities of large-scale bridging.

One of my readers preparing for public cloud deployment sent me an interesting observation:

I pushed to use infrastructure-as-code as we move to Azure, but I’m receiving a lot of pushback due to most of the involved parties not having any experience with code. Management is scared to use any kind of “homegrown” tools that only a few would understand. I feel like I’m stuck deploying and managing the environment manually.

It looks like a bad case of suboptimal terminology for this particular audience. For whatever reason, some infrastructure engineers prefer to stay as far away from programming as possible¹, and infrastructure-as-code sounds like programming to them.