BGP Policies (part 1)

7 March 2022 |

At the most basic level, there are only three BGP policies: pushing traffic through a specific exit point; pulling traffic through a specific entry point; preventing a remote AS (more than one AS hop away) from transiting your AS to reach a specific destination. In this series I’m going to discuss different reasons for these kinds of policies, and different ways to implement them in interdomain BGP.

Quality is (too often) the missing ingredient

3 January 2022 | Comments Off on Quality is (too often) the missing ingredient

Software Eats the World?

I’m told software is going to eat the world very soon now. Everything already is, or will be, software based. To some folks, this sounds completely wonderful, but—leaving aside the privacy issues—I still see an elephant in the room with this vision of the future.


Let me give you some recent examples.

First, ceiling fans. Modern ceiling fans, in case you didn’t know, don’t rely on the wall switch and pull chains. Instead, they rely on remote controls. This is brilliant—you can dim the light, change the speed of the fan, etc., from a remote control. No unsightly chains hanging from the ceiling.

Thoughts on Auto Disaggregation and Complexity

15 November 2021 | Comments Off on Thoughts on Auto Disaggregation and Complexity

Way in the past, the EIGRP team (including me) had an interesting idea–why not aggregate routes automatically as much as possible, along classless bounds, and then deaggregate routes when we could detect some failure was causing a routing black hole? To understand this concept better, consider the network below.

Keith’s Law (1)

28 September 2021 | Comments Off on Keith’s Law (1)

I sometimes reference Keith’s Law in my teaching, but I don’t think I’ve ever explained it. Keith’s Law runs something like this:

Any large external step in a system’s capability is the result of many incremental changes within the system.

Thoughts on the Collapsed Spine

21 September 2021 |

One of the designs I’ve been encountering a lot of recently is a “collapsed spine” data center network, as shown in the illustration below.

Russ’ Rules of Network Design

14 September 2021 | Comments Off on Russ’ Rules of Network Design

We have the twelve truths of networking, and possibly Akin’s Laws, but is there a set of rules for network design? I couldn’t find one, so I decided to create one, containing 18 laws I’ve listed below.

Marketing Wins

30 August 2021 | Comments Off on Marketing Wins

Off-topic post for today …

In the battle between marketing and security, marketing always wins. This topic came to mind after reading an article on using email aliases to control your email—

For example, if you sign up for a lot of email newsletters, consider doing so with an alias. That way, you can quickly filter the incoming messages sent to that alias—these are probably low-priority, so you can have your provider automatically apply specific labels, mark them as read, or delete them immediately.

It always takes longer than you think

23 August 2021 | Comments Off on It always takes longer than you think

Everyone is aware that it always takes longer to find a problem in a network than it should. Moving through the troubleshooting process often feels like swimming in molasses—you’re pulling hard, and progress is being made, but never fast enough or far enough to get the application back up and running before that crucial deadline. The “swimming in molasses effect” doesn’t end when the problem is found out, either—repairing the problem requires juggling a thousand variables, most of which are unknown, combined with the wit and sagacity of a soothsayer to work with vendors, code releases, and unintended consequences.

The Centralization of the Internet

16 August 2021 | Comments Off on The Centralization of the Internet

My article on Internet centralization just published over at The Public Discourse—

Most of the Internet’s traffic now flows through the networks of a few large companies rather than a multitude of small transit providers, and the Internet’s physical infrastructure is being reshaped to meet this new reality. But relying on a few providers to host all the content on the Internet makes it possible for just a few companies to shut down entire services or control speech.

The Grass is Always Greener

9 August 2021 |

This last week I was talking to someone at a small startup that intends to eliminate all the complex routing from campus networks. In the past, when reading blog posts about Kubernetes, I’ve read about how it was designed to eliminate routing protocols because “routing protocols are so complex.”

Color me skeptical.