Blog Posts in July 2023

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.

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.

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.

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.

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 ;)

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!

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.

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.