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…

History of Networking: Tony P on BIER

26 April 2018 | Comments Off on History of Networking: Tony P on BIER

Deconfusing the Static Route

2 April 2018 | Comments Off on Deconfusing the Static Route

Configuring a static route is just like installing an entry directly in the routing table (or the RIB). I have been told this many times in my work as a network engineer by operations people, coders, designers, and many other folks. The problem is that it is, in some routing table implementations, too true. To…

Responding to Readers: Questions on Microloops

5 March 2018 |

Two different readers, in two different forums, asked me some excellent questions about some older posts on mircoloops. Unfortunately I didn’t take down the names or forums when I noted the questions, but you know who you are! For this discussion, use the network show below. In this network, assume all link costs are one,…