The Hedge Podcast #53: Deprecating Interdomain ASM

23 September 2020 |

Interdomain Any-source Multicast has proven to be an unscalable solution, and is actually blocking the deployment of other solutions. To move interdomain multicast forward, Lenny Giuliano, Tim Chown, and Toerless Eckhert wrote RFC 8815, BCP 229, recommending providers “deprecate the use of Any-Source Multicast (ASM) for interdomain multicast, leaving Source-Specific Multicast (SSM) as the recommended interdomain mode of multicast.”

Technologies that Didn’t: CLNS

22 September 2020 |

The Open Systems Interconnect (OSI) model is the most often taught model of data transmission—although it is not all that useful in terms of describing how modern networks work. What many engineers who have come into network engineering more recently do not know is there was an entire protocol suite that went with the OSI model. Each of the layers within the OSI model, in fact, had multiple protocols specified to fill the functions of that layer. For instance, X.25, while older than the OSI model, was adopted into the OSI suite to provide point-to-point connectivity over some specific kinds of physical circuits. Moving up the stack a little, there were several protocols that provided much the same service as the widely used Internet Protocol (IP).

The Hedge Podcast 44: Pete Lumbis and Open Source

15 July 2020 | Comments Off on The Hedge Podcast 44: Pete Lumbis and Open Source

Open source software is everywhere, it seems—and yet it’s nowhere at the same time. Everyone is talking about it, but how many people and organizations are actually using it? Pete Lumbis at NVIDIA joins Tom Ammon and Russ White to discuss the many uses and meanings of open source software in the networking world.

On the ‘net: Routing in DC Fabrics

30 April 2020 | Comments Off on On the ‘net: Routing in DC Fabrics

Hosts Roopa Prabhu and Pete Lumbis are joined by a special guest to the podcast, Russ White! The group come together virtually to discuss what we should think about when it comes to routing protocols in the datcenter. What are the tradeoffs when using traditional protocols like OSPF or BGP? What about new protocols like RIFT or a hybrid approach with things like BGP-link state? Spoiler alert: it depends.

Understanding Internet Peering

6 April 2020 | Comments Off on Understanding Internet Peering

The world of provider interconnection is a little … “mysterious” … even to those who work at transit providers. The decision of who to peer with, whether such peering should be paid, settlement-free, open, and where to peer is often cordoned off into a separate team (or set of teams) that don’t seem to leak a lot of information. A recent paper on current interconnection practices published in ACM SIGCOMM sheds some useful light into this corner of the Internet, and hence is useful for those just trying to understand how the Internet really works.

History of Networking: Adrian Farrel and PCE

17 March 2020 |

Path Computation Element (PCE) is designed to allow the computation of paths for MPLS and GMPLS Point to Point and
Point to Multi-point Traffic Engineered LSPs. Adrian Farrel, who was involved in the early work on designing an specifying PCE, joins us in this episode of the History of Networking to describe the purposes, process, and challenges involved. You can read more about Adrian on his personal home page, and about PCE on the IETF WG page.

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?

BIER Basics

8 April 2019 |

Multicast is, at best, difficult to deploy in large scale networks—PIM sparse and BIDIR are both complex, adding large amounts of state to intermediate devices. In the worst case, there is no apparent way to deploy any existing version of PIM, such as large-scale spine and leaf networks (variations on the venerable Clos fabric). BEIR,…

Research: Facebook’s Edge Fabric

23 August 2018 | Comments Off on Research: Facebook’s Edge Fabric

The Internet has changed dramatically over the last ten years; more than 70% of the traffic over the Internet is now served by ten Autonomous Systems (AS’), causing the physical topology of the Internet to be reshaped into more of a hub-and-spoke design, rather than the more familiar scale-free design (I discussed this in a…

Research: Robustness in Complex Systems

21 May 2018 | Comments Off on Research: Robustness in Complex Systems

While the network engineering world tends to use the word resilience to describe a system that will support rapid change in the real world, another word often used in computer science is robustness. What makes a system robust or resilient? If you ask a network engineer this question, the most likely answer you will get…