Engagement Farming

One of my readers asked for my opinion about the following masterpiece posted on (where else) LinkedIn¹:

netlab 1.6.1: BGP Reports, Markdown Support

We added just a few small features in netlab release 1.6.1¹:

• Markdown reports: netlab report command can produce Markdown-formatted reports, making it extremely easy to include them in your documentation (assuming you’re using Markdown to write it)
• If you’re using BGP in your labs, you can generate reports on BGP autonomous systems and BGP neighbors.
• I made locations of default files configurable. I’m using this feature in large projects where I want to have a shared set of project-wide defaults for topologies stored in different directories.

Getting Comfortable with the Command Line

More than a dozen years after the SDN brouhaha erupted, some people still haven’t got the memo on the obsolescence of CLI. For example, Julia Evans tries to make people comfortable with the command line. Has nobody told her it’s like teaching COBOL?

On a more serious note: you OUGHT TO master Linux CLI and be comfortable using CLI commands on network devices and servers. Her article has tons of useful tips and is definitely worth reading.

Free Subscription No Longer Needed to Watch the ipSpace.net Videos

I’m publishing a link to a free ipSpace.net video several times each month, usually with a notice saying you need free subscription to watch the video. I had to put that limitation in place when I was hosting videos on AWS S3 – unlimited streaming could explode my AWS bill.

Recently I moved the video storage to Cloudflare R2. Cloudflare claims they will never charge egress fees, and as long as that’s true (and they don’t start chasing me for generating too much traffic) I see no reason to bother you with registration and login procedures – starting immediately, you can watch the free ipSpace.net videos without an ipSpace.net account.

Worth Reading: Networking for AI Workloads

Sharada Yeluri (Senior Director of Engineering at Juniper Networks) wrote a long article describing the connectivity requirements of AI workloads and new approaches to Ethernet fabrics. Definitely worth reading if you’re interested in these topics.

New Project: BGP Hands-On Labs

Approximately 30 years ago I managed to persuade the powers-that-be within Cisco’s European training organization that they needed a deep-dive BGP course, resulting in a 3 (later 5) day Advanced BGP Configuration and Troubleshooting (ABCT) course¹. I was delivering that course for close to a decade, and gradually built a decent story explaining the reasoning and use cases behind most of (then available) BGP features, from simple EBGP sessions to BGP route reflectors and communities².

Now imagine having more than a dozen hands-on labs that go with the “BGP from rookie to hero” story available for any platform of your choice³. I plan to make that work (eventually) as an open-source project that you’ll be able to download and run free-of-charge.

netlab 1.6.0: New Commands, Reports, and External Connectivity

netlab release 1.6.0 has (probably) the longest release notes so far as it contains so many user-visible new features including:

New Commands

Some users were complaining how complex it was to use netlab create command to create graphs, inspect data structures, or create custom reports. They might find the new commands easier to use:

Worth Reading: MP-TCP in Hybrid Access Networks

Wouldn’t it be nice if your home router (CPE) could use DSL (or slow-speed fibre) and LTE connection at the same time? Even better: run a single TCP session over both links? The answer to both questions is YES, of course it could do that, if only your service provider would be interested in giving you that option.

We solved similar problems with multilink PPP in the networking antiquity, today you could use a CPE with an MP-TCP proxy combined with a Hybrid Access Gateway in the service provider network. For more details, read the excellent Increasing broadband reach with Hybrid Access Networks article by prof. Olivier Bonaventure and his team.

Worth Reading: Eyes Like Saucers

Gerben Wierda published a nice description of common reactions to new unicorn-dust-based technologies:

• Eyes that glaze over
• Eyes like saucers
• Eyes that narrow

He uses generative AI as an example to explain why it might be a bad idea that people in the first two categories make strategic decisions, but of course nothing ever stops people desperately believing in vendor fairy tales, including long-distance vMotion, SDN or intent-based networking.

Multipath TCP (MPTCP) Resources

Brian Carpenter published a list of Multipath TCP resources to one of the IETF mailing lists¹:

• Modern Multipath Transport Protocols – an ebook by prof. Olivier Bonaventure describing QUIC, multipath TCP and multipath QUIC.
• Multipath TCP Wiki
• Multipath TCP for Linux
• Multipath TCP Python extension module

You might also want to listen to the Multipath TCP podcast we recorded with Apple engineers in 2019.

Configuring Linux Traffic Control in a Sane Way

Smart engineers were forever using Linux (in particular, its traffic control/queue discipline functionality) to simulate WAN link impairment. Unfortunately, there’s a tiny hurdle you have to jump across: the tc CLI is even worse than iptables.

A long while ago someone published a tc wrapper that simulates shitty network connections and (for whatever reason) decided to call it Comcast. It probably does the job, but I would prefer to have something in Python. Daniel Dib found just that – tcconfig – and used it to simulate WAN link behavior on VMware vSphere.

Fun Reading: History of the Early Internet

Bruce Davie collected numerous articles describing various aspects of early Internet history and pre-Internet days, including A Brief History of the Internet and The Design Philosophy of the DARPA Internet Protocols.

Have fun ;)

Worth Watching: Ethernet Thick Yellow Cable

Justus sent me an email with an interesting link:

Since you love to make comparisons to the good ol’ thick yellow cable while I as a mid-30 year old adult have no idea what you are talking about: Computerphile made a video about Ethernet on the occasion of its 50th birthday. The university of Nottingham got the chance to show their museum pieces :-) (about 8:45 min).

Thanks a million!

Worth Reading: Another BGP Session Reset Bug

Emile Aben is describing an interesting behavior observed in the Wild West of the global Internet: someone started announcing BGP paths with an unknown attribute, which (regardless of RFC 7606) triggered some BGP session resets.

One would have hoped we learned something from the August 2010 incident (supposedly caused by a friend of mine 😜), but it looks like some things never change. For more details, watch the Network Security Fallacies and Internet Routing Security webinar.

Worth Reading: AI Does Not Help Programmers

On the Communications of the ACM web site, Bertrand Meyer argues that (contrary to the exploding hype) AI Does Not Help Programmers:

As a programmer, I know where to go to solve a problem. But I am fallible; I would love to have an assistant who keeps me in check, alerting me to pitfalls and correcting me when I err. A effective pair-programmer. But that is not what I get. Instead, I have the equivalent of a cocky graduate student, smart and widely read, also polite and quick to apologize, but thoroughly, invariably, sloppy and unreliable. I have little use for such supposed help.

Not surprisingly, my experience is pretty close to what he’s describing. AI is the way to go if you want something that looks reasonable (at a first glance), but not if you want to get something right. Unfortunately, there’s a bit of a difference between marketing and engineering: networks that are configured 90% correctly sometimes fail to do what you expect them to do.

Worth Reading: What Is Going on With BGP?

Ignas Bagdonas sent a phenomenal summary of recent BGP developments to the RIPE Routing WG mailing list. Enjoy!

Worth Reading: Always the Same Warning Signs

Found an interesting article describing the shenanigans of a biotech startup. Admittedly, it has nothing to do with networking apart from the closing paragraph…

But people will find all sorts of ways to believe what they want to believe, to avoid hearing things that they don’t want to hear, and to avoid thinking about things that are too worrisome to contemplate.

… which is a perfect description of why people believe in centralized control planes, flow-based forwarding, or long-distance vMotion.

Summer Break 2023

Long story short: it’s time for another summer break, as people reporting my bloopers – THANK YOU!!! – know only too well. I plan to be back in early autumn rolling out tons of new content.

I’ll do my best to reply to support requests (it will take longer than usual), and probably won’t be able to resist publishing a few lightweight netlab-related blog posts. If you get bored there’s still over 400 hours of existing content, over 100 podcast episodes, and thousands of blog posts.

In the meantime, get away from work, turn off the Internet, and enjoy a few days in your favorite spot with your loved ones!

Use FRR Containers to Learn Routing Protocol Fundamentals

An anonymous commenter asked this highly relevant question about my Internet routing security lab:

What are the smallest hardware requirements to run the lab.

TL&DR: 2 GB RAM, 2 vCPU

Now for the more precise answer (aka “it depends”).

When a Device Without an IP Address Wants to Play the IP Game

After I published the Source IP Address in Multicast Packets blog post, Erik Auerswald sent me several examples of network devices sending IP packets with source IP address set to 0.0.0.0:

• Cisco wireless access points using 0.0.0.0 as the source IP address in VRRP packets.
• Extreme (formerly Avaya) switches sending IGMP queries with source IP address 0.0.0.0 on VLANs on which they have no IP address.