Impact of Centralized Control Plane Partitioning

A long-time reader sent me a series of questions about the impact of WAN partitioning in case of an SDN-based network spanning multiple locations after watching the Architectures part of Data Center Fabrics webinar. He therefore focused on the specific case of centralized control plane (read: an equivalent of a stackable switch) with distributed controller cluster (read: switch stack spread across multiple locations).

Rant: Broadcom and Network Operating System Vendors

Minh Ha left the following rant as a comment on my 5-year-old What Are The Problems with Broadcom Tomahawk? blog post. It’s too good to be left gathering dust there. Counterarguments and other perspectives are highly welcome.

So basically a lot of vendors these days are just glorified Broadcom resellers :p. It’s funny how some of them try to up themselves by saying they differentiate their offerings with their Network OS.

Thank You for All the Great Work Miha

Almost exactly a year ago Miha Markočič joined the ipSpace.net team. He was fresh out of university, fluent in Python, but with no networking or automation background… so I decided to try my traditional method of getting new team members up to speed: throw them into the deep water, observe how quickly they learn to swim, and give them a few tips if it seems like they might be drowning.

It worked out amazingly well. Miha quickly mastered the intricacies of AWS and Azure, and created full-stack automation solutions in Ansible, Terraform, CloudFormation and Azure Resource Manager to support the AWS and Azure webinars, and the public cloud networking online course.

Worth Reading: Understanding Table Sizes on the Arista 7050QX-32

Arista published a blog post describing the details of forwarding table sizes on 7050QX-series switches. The description includes the base mode (fixed tables), unified forwarding tables and even the IPv6 LPM details, and dives deep into what happens when the switch runs out of forwarding table entries.

Too bad they’re describing an ancient Trident-2 ASIC (I last mentioned switches using it in 2017 Data Center Fabrics update). Did NDA expire on that one?

Worth Reading: AAA Deep Dive on Cisco Devices

Decades ago I understood the intricacies of AAA on Cisco IOS. These days I wing it and keep throwing spaghetti at the virtual wall until something sticks and I can log in (after all, it’s all in a lab, and I’m interested in routing protocols not interactions with TACACS+ server).

If you’re experiencing similar challenges you might appreciate AAA Deep Dive on Cisco Devices by the one and only Daniel Dib.

FreeRTR Deep Dive on Software Gone Wild

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

In today’s evolving landscape of whitebox, brightbox, and software routing, a small but incredibly comprehensive routing platform called FreeRTR has quietly been evolving out of a research and education service provider network in Hungary. 

Kevin Myers of IPArchitechs brought this to my attention around March of 2019, at which point I went straight to work with it to see how far it could be pushed.

Build Virtual Lab Topology: VirtualBox Support

When I blogged about release 0.2 of my lab-building tool, Kristian Larsson was quick to reply: “now do vrnetlab”. You could guess what my reply was (hint: “submit a pull request”), but I did realize I’d have to add multi-provider support before that would make sense.

Release 0.3 adds support for multiple virtualization providers. You can run six different platforms on vagrant-libvirt (assuming you build the boxes), and I added rudimentary support for Vagrant provider for VirtualBox:

Deploying Advanced AWS Networking Features

Miha Markočič created sample automation scripts (mostly Terraform configuration files + AWS CLI commands where needed) deploying these features described in AWS Networking webinar:

• IP multicast deployment (video)
• Web Application Firewall deployment (video)
• Network Load Balancer deployment (video)
• Inter-region VPC Peering deployment (video)

To recreate them, clone the GitHub repository and follow the instructions.

Fixing XML-to-JSON Conversion Challenges

In the last weeks I described the challenges you might face when converting XML documents that contain lists with a single element into JSON, be it on device (Nexus OS) or in an Ansible module. Now let’s see how we can fix that.

New Webinar: Network Automation Concepts

There’s one more thing I feel needs to be done before I go for that coffee break: a webinar focusing on network automation concepts (as opposed to replacing Excel with YAML and Ansible or Becoming a Python Coder). Here’s a rough list of concepts I think should be in there:

• Data models and data stores
• Data model transformations
• Single source of truth
• Abstraction layers
• Idempotency

Worth Reading: Cloud Complexity Lies

Anyone who spent some time reading cloud providers' documentation instead of watching slide decks or vendor keynotes knows that setting up infrastructure in a public cloud is not much simpler than doing it on-premises. You will outsource hardware management (installations, upgrades, replacements…) and might deal with an orchestration system provisioning services instead of configuring individual devices, but you still have to make the same decisions, and take the same set of responsibilities.

Obviously that doesn’t look good in a vendor slide deck, so don’t expect them to tell you the gory details (and when they start talking about the power of declarative API you know you have a winner)… but every now and then someone decides to point out the state of emperor’s clothes, this time Gerben Wierda in his The many lies about reducing complexity part 2: Cloud.

For public cloud networking details, check out our cloud webinars and online course.

Podcast: IPv6 in the Cloud

In December 2020 Ed Horley invited me to a chat about IPv6 in the public cloud. While I usually don’t want to think about a protocol that’s old enough to buy its own beer in US, we nonetheless had interesting discussions (including the need for frequent RA messages in AWS VPC).

How Important is BGP RPKI?

Corey Quinn mentioned me in a tweet linking to AWS announcement that they are the biggest user of BGP RPKI (by the size of signed address space) worldwide. Good for them – I’m sure it got their marketing excited. It’s also trivial to do once you have the infrastructure in place. Just saying…

On a more serious front: how important is RPKI and what misuses can it stop?

If you’ve never heard of RPKI, the AWS blog post is not too bad, Nick Matthews wrote a “look grandma, this is how it works” version in 280-character installments, and you should definitely spend some time exploring MANRS resources. Here’s a short version for differently-attentive ;))

XML-to-JSON Information Loss, Cisco Nexus OS Edition

Last week I wrote about the interesting challenges you might encounter when using data generated by a Junos device in an Ansible playbook. Unfortunately it’s not just Junos – every system built around XML-based data structures might experience the same issues, including Cisco Nexus OS.

Repost: VMware Fault Tolerance Woes

I always claimed that VMware Fault Tolerance makes no sense. After all, the only thing it does is protect a VM against a server hardware failure… in the world where software crashes are way more common, and fat fingers cause most of the outages.

But wait, it gets worse, the whole thing is incredibly complex – you might like this description Minh Ha left as a comment to my Fifty Shades of High Availability blog post.

Build Virtual Lab Topology: Dual Stack Addressing, ArcOS and Junos Support

In mid-December I announced a set of tools that will help you build Vagrant-based remote labs much faster than writing Vagrantfiles and Ansible inventories by hand.

In early January I received a nice surprise: Dave Thelen not only decided to use the tool, he submitted a pull request with full-blown (and correctly implemented) ArcOS support. A few days later I managed to figure out what needs to be configured on vSRX to make it work, added Junos support, and thus increased the number of supported platforms to six (spanning five different operating systems).

Video: Multi-Layer Switching and Tunneling

After discussing the technology options one has when trying to get a packet across the network, we dived deep into two interesting topics:

• How do you combine packet forwarding at multiple layers of OSI stack (multi-layer switching)?
• What happens when you do layer-N forwarding over layer-M transport core where N <= M (example: IPv6 packets over IPv4 packets) aka tunneling?

You’ll find more details (including other hybrids like Loose Source Routing) in Multi-Layer Switching and Tunneling video.

Beware XML-to-JSON Information Loss (Junos with Ansible)

When you want to transport a complex data structure between components of a distributed system you’re usually using a platform-independent data encoding format like XML, YAML, or JSON.

XML was the hip encoding format in days when Junos and Cisco Nexus OS was designed and lost most of its popularity in the meantime due to its complexity (attributes, namespaces…) that makes it hard to deal with XML documents in most programming languages.

JSON is the new cool kid on the block. It’s less complex than XML, maps better into data structures supported by modern programming languages, and has decently fast parser implementations.

Imperative and Declarative API: Another Pile of Marketing Deja-Moo

Looks like some vendor marketers (you know, the same group of people who brought us the switching/routing/bridging stupidity) felt the need to go beyond the usual SDN and intent-based hype and started misusing the imperative versus declarative concepts. Unfortunately some networking engineers fell for the ploy; here’s a typical feedback along these lines I got from one of my readers:

I am frustrated by most people’s shallow understanding API’s, especially the differences between declarative (“what”) and imperative (“how”) API’s, and how that impacts one’s operations. Declarative APIs are the key pillar of what many vendors call “policy” or “intent-based” networking.

Let’s try to unravel that.

Automation Win: Chatops-Based Security

It’s amazing how quickly you can deploy new functionality once you have a solid foundation in place. In his latest blog post Adrian Giacometti described how he implemented a security solution that allows network operators to block source IP addresses (identified by security tools) across dozens of firewalls using a bot listening to a Slack channel.

Would you be surprised if I told you we covered similar topics in our automation course? ?