The Hedge Podcast Episode 28: Intent Based Networking in the IRTF

25 March 2020 | Comments Off on The Hedge Podcast Episode 28: Intent Based Networking in the IRTF

Intent based networking is on the upslope of the hype cycle right now. In this episode of the Hedge, Alex Clemm and Jeff Tantsura join Alvaro Retana and Russ White for a discussion of Intent-Based Networking – Concepts and Definitions, a draft working its way through the Internet Research Task Force.

The Hedge Podcast Episode 23: The MOPS Working Group

19 February 2020 | Comments Off on The Hedge Podcast Episode 23: The MOPS Working Group

The IETF works on many things beyond IP and routing—the Media Operations (MOPS) working group is gathering input on media-related operational issues and practices, including “proposed technologies related to the deployment, engineering, and operation of media streaming and manipulation protocols and procedures in the global Internet (inter-domain) and within-domain networking.” Leslie Daigle and Eric Vyncke, the co-chairs of the MOPS working group, join Alvaro Retana and Russ White to discuss the work they are doing.

The Hedge Podcast Episode 20: Whatever Happened to Software Defined Networking

29 January 2020 | Comments Off on The Hedge Podcast Episode 20: Whatever Happened to Software Defined Networking

There was a time when Software Defined Networking was going to take over the entire networking world—just like ATM, FDDI, and … so many others before. Whatever happened to SDN, anyway? What is its enduring legacy in the world of network engineering? Terry Slattery, Tom Ammon, and Russ White gather at the hedge to have a conversation about whatever happened to SDN?

The History of Multipath TCP with Olivier Bonaventure

26 November 2019 | Comments Off on The History of Multipath TCP with Olivier Bonaventure

MultiPath TCP (MPTCP) is an effort towards enabling the simultaneous use of several IP-addresses/interfaces by a modification of TCP that presents a regular TCP interface to applications, while in fact spreading data across several subflows. Benefits of this include better resource utilization, better throughput and smoother reaction to failures.

SDN, AI, and DevOps

7 October 2019 |

According to the recent SONAR report, 52% of respondents reported they are using Software Defined Networking (SDN) tools to automate their networks, while 57% reported they are using network management tools. The report notes “52% may be slightly exaggerated, depending on how one defines SDN…” Which leads naturally to the question—what the difference between SDN and DevOps is, and how does AI figure into both or either of these.  SDN, DevOps, and AI describe separate and overlapping movements in the design, deployment, and management of networks. While they are easy to confuse, they have three different origins and meanings.

Software Defined Networking grew out of research efforts to build and deploy experimental control planes, either distributed or centralized. SDN, however, quickly became associated with replacing some or all the functions of a distributed control plane with a centralized controller, particularly in order to centralize policy related to the control plane such as traffic engineering. SDN solutions always work through a programmatic interface designed to primarily supply forwarding information to network devices.

The Hedge Episode 6: Geoff Huston on DoH

11 September 2019 | Comments Off on The Hedge Episode 6: Geoff Huston on DoH

In this episode of the Hedge, Geoff Huston joins Tom Ammon and I to finish our discussion on the ideas behind DNS over HTTPS (DoH), and to consider the implications of its widespread adoption. Is it time to bow to our new overlords?

The Hedge Episode 5: Geoff Huston on DoH

10 September 2019 | Comments Off on The Hedge Episode 5: Geoff Huston on DoH

In this episode of the Hedge, Geoff Huston joins Tom Ammon and I to discuss the ideas behind DNS over HTTPS (DoH), and to consider the implications of its widespread adoption. Is it time to bow to our new overlords?

History of TCP/IP with Doug Comer

3 September 2019 | Comments Off on History of TCP/IP with Doug Comer


The Transmission Control Protocol, or TCP, is one of the foundational technologies of packet switched networks. TCP not only provides windowed flow control, it also manages the retransmission of data when errors are detected, and sockets for addressing individual applications on a host. Doug Comer was involved in the early development of TCP/IP.

Stop Using the OSI Model

2 September 2019 |

We all use the OSI model to describe the way networks work. I have, in fact, included it in just about every presentation, and every book I have written, someplace in the fundamentals of networking. But if you have every looked at the OSI model and had to scratch your head trying to figure out how it really fits with the networks we operate today, or what the OSI model is telling you in terms of troubleshooting, design, or operation—you are not alone. Lots of people have scratched their heads about the OSI model, trying to understand how it fits with modern networking. There is a reason this is so difficult to figure out.

The OSI Model does not accurately describe networks.

What set me off in this particular direction this week is an article over at Errata Security:

The OSI Model was created by international standards organization for an alternative internet that was too complicated to ever work, and which never worked, and which never came to pass. Sure, when they created the OSI Model, the Internet layered model already existed, so they made sure to include today’s Internet as part of their model. But the focus and intent of the OSI’s efforts was on dumb networking concepts that worked differently from the Internet.

DNS Query Minimization and Data Leaks

26 August 2019 |

When a recursive resolver receives a query from a host, it will first consult any local cache to discover if it has the information required to resolve the query. If it does not, it will begin with the rightmost section of the domain name, the Top Level Domain (TLD), moving left through each section of the Fully Qualified Domain Name (FQDN), in order to find an IP address to return to the host, as shown in the diagram below.

This is pretty simple at its most basic level, of course—virtually every network engineer in the world understands this process (and if you don’t, you should enroll in my How the Internet Really Works webinar the next time it is offered!). The question almost no-one ever asks, however, is: what, precisely, is the recursive server sending to the root, TLD, and authoritative servers?