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Upcoming Webinar: How Routers Really Work

On December 13, 2019, I’m giving a three-hour webinar over at Safari Books on How Routers Really Work. From the description:

This training will peer into the internal components of a router, starting with an explanation of how a router switches packets. This walk through of a switching path, in turn, will be used as a foundation for explaining the components of a router, including the various tables used to build forwarding tables and the software components used to build these tables.

The Hedge Podcast 13: Ivan Pepelnjak

In this episode of the Hedge, Tom Ammon and Russ White are joined by Ivan Pepelnjak of to talk about being old, knowing about how things are going to break before they do, and being negative. Along the way, we discuss the IETF, open source, and many other aspects of the world of network engineering.

IPv6 and Leaky Addresses

One of the recurring myths of IPv6 is its very large address space somehow confers a higher degree of security. The theory goes something like this: there is so much more of the IPv6 address space to test in order to find out what is connected to the network, it would take too long to scan the entire space looking for devices. The first problem with this myth is it simply is not true—it is quite possible to scan the entire IPv6 address space rather quickly, probing enough addresses to perform a tree-based search to find attached devices. The second problem is this assumes the only modes of attack available in IPv4 will directly carry across to IPv6. But every protocol has its own set of tradeoffs, and therefore its own set of attack surfaces.

The Hedge Episode 12: Cyberinsecurity with Andrew Odlyzko

There is a rising tide of security breaches. There is an even faster rising tide of hysteria over the ostensible reason for these breaches, namely the deficient state of our information infrastructure. Yet the world is doing remarkably well overall, and has not suffered any of the oft-threatened giant digital catastrophes. ndrew Odlyzko joins Tom Ammon and I to talk about cyber insecurity.

History of Networking: DUAL with JJ Garcia

JJ Garcia is Distinguished Professor of Computer Science and Engineering and Jack Baskin Endowed Chair of Computer Engineering at USC Santa Cruz. He first became involved in packet networks in the 1980’s, eventually inventing the Diffusing Update Algorithm (DUAL), which later became the basis for the Enhanced Interior Gateway Protocol (EIGRP). You can find more information about Dr. Garcia at his personal page.

Simpler is Better… Right?

A few weeks ago, I was in the midst of a conversation about EVPNs, how they work, and the use cases for deploying them, when one of the participants exclaimed: “This is so complicated… why don’t we stick with the older way of doing things with multi-chassis link aggregation and virtual chassis device?” Sometimes it does seem like we create complex solutions when a simpler solution is already available. Since simpler is always better, why not just use them? After all, simpler solutions are easier to understand, which means they are easier to deploy and troubleshoot.

The problem is we too often forget the other side of the simplicity equation—complexity is required to solve hard problems and adapt to demanding environments. While complex systems can be fragile (primarily through ossification), simple solutions can flat out fail just because they can’t cope with changes in their environment.

On the Web: RFC1925 Rule6

Early on in my career as a network engineer, I learned the value of sharing… For instance, when I could not figure out why a particular application was not working correctly, it was always useful to blame the application. Conversely, the application owner was often quite willing to share their problems with me, as well,…

The Hedge Episode 11: Roland Dobbins on Working Remotely

Network engineering and operations are both “mental work” that can largely be done remotely—but working remote is not only great in many ways, it is also often fraught with problems. In this episode of the Hedge, Roland Dobbins joins Tom and Russ to discuss the ins and outs of working remote, including some strategies we have found effective at removing many of the negative aspects.

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