The Best MPLS Lecture on the Net

The title says it all. Professor Karandikar gives two amazing lectures on MPLS and MPLS-TE that most engineers should hope to know cold. I watch it probably once every few months. Not saying much for my memory these days. It is an amazing amount of material delivered very precisely. Great stuff! I added some figures to […]

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Ethernet Switch Fabric Cards

I was working with a buddy today about switch fabric cards in the nexus 7000 and not doing a very good job at explaining it, so I figured I would draw some pictures. The conversation was around how adding more fabric cards increases the bandwidth. I think some, myself included growing up on Catalyst 6500’s […]

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Help Wanted: Cultural Change

This post is low on the nerdalert meter and more of the arts, rather than the science. Earlier this year, Level3 blogged about their new initiative of training ~%20 of their 11,000 person staff to be “change agents” in order to cross-pollinate their peers, the notion that change is healthy for the company (speculating). Change […]

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SDN and OpenFlow Quotes from some of the Best

Like anyone reading this, we are avid consumers (in my case leech) of information. I put together some quote from people regarding SDN and OpenFlow. Most of the people in the list are intrinsic in helping me shape my own views regarding technology with the outstanding content, ideas and research they generate. “Think of it as a […]

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Auto-RP and usage of "ip pim autorp listener"

After reading several forums with people arguing about what routers should be configured with the "ip pim autorp listener" command, I have decided to write this post explaining things in my own way (of course, with a lot of pictures, as usual).

MPLS VPLS configuration with Juniper JunOS.

Posting a Juniper VPLS how-to on a couple of J-series routers. Have been pretty SDN focused lately so wanted to get some real stuff in for a post. Docs on JunOS VPLS can be shaky so nothing like a couple real configs to plugin your address in the lab if having problems with L2 VPNs. […]

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The Fabric ERA

“Fabric” is a loosely used term, which today creates more confusion instead of offering direction. What exactly is a Fabric ? What is a Switch Fabric? Greg Ferro did a post here explaining how Ethernet helped the layer 2 switch fabric evolve. Sadly the use of switch fabric did not stop there. And this is […]

The Bufferbloat Bandwidth Death March

Some puzzle pieces of a picture puzzle.Latency much more than bandwidth governs actual internet “speed”, as best expressed in written form by Stuart Chesire’s It’s the Latency, Stupid rant and more formally in Latency and the Quest for Interactivity.

Speed != bandwidth despite all of what an ISP’s marketing department will tell you. This misconception is reflected up to and including FCC Commissioner Julius Genachowski, and is common even among technologists who should know better, and believed by the general public. You pick an airplane to fly across the ocean, rather than a ship, even though the capacity of the ship may be far higher.

The Internet could and should degrade gradually in the face of load; but today’s Internet does not degrade gracefully due to bufferbloat. Instead, performance falls off a cliff. We are lemmings on migration.

The Internet is designed to run as fast as it can, and so will fill any capacity network link as soon as you have any applications that asks to do so. We have more and more such applications, and the buffers get bigger each hardware generation, though usually operated at a small fraction of that possible bandwidth. As soon as a network or network link reaches100% capacity, the usually grossly Continue reading

SDN Business Cases

We have a few problems in the networking construct and as much as I dont want to say,  paradigm, ecosystem, abstraction etc. a million times there may be a couple hundred in the following writeup. The following document are some rationalizations that have come up over the past recent months/years for some new abstractions in networking that […]

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BIGDATA BUBBLE – Infinite Possibilities

If you live in Australia you probably have heard about the Mining Boom, so was the famous “DotCOM bubble” in way back in 199x . Recently, this new buzzword “BigData” in IT data mining space seems to be a new technology trend for many enterprises and Telco’s. They need bigdata to be implemented to solve […]

Five Features of Brocade VCS

Virtual Cluster Switching (VCS) is Brocade's brand of datacenter ethernet switching. VCS allows for the creation of a network fabric that's capable of converging storage and data traffic via standards-based datacenter bridging. It also solves the “Spanning Tree Protocol (STP) problem” by implementing a standards-based TRILL data plane paired with their own control plane in the form of Fabric Shortest Path First (FSPF). This data + control plane enable the “routing” of MAC addresses through the fabric, negates the need for STP, enables the use of all cabled links, and prevents traffic loops. VCS is only (currently) available on the VDX line of switches from Brocade.

In this post I'm going to outline five aspects of VCS that I found particularly interesting or unique. This is a companion article to an earlier one titled Five Functional Facts about FabricPath where I broke down five features of Cisco's fabric technology.

A Milestone Reached: CoDel is in Linux!

Some puzzle pieces of a picture puzzle.The CoDel AQM algorithm by Kathie Nichols and Van Jacobson provides us with an essential missing tool to control queues properly. This work is the culmination of their at three major attempts to solve the problems with AQM algorithms over the last 14 years.

 

Eric Dumazet wrote the codel queuing discipline (based on a quick prototype by Dave Täht, who spent the last year working 60 hour weeks on bufferbloat) which landed in net-next a week or two ago; yesterday, net-next was merged into the Linux mainline for inclusion in the next Linux release.  Eric also implemented a fq_codel queuing discipline, combining fair queuing and CoDel  (pronounced “coddle”), and it works very well.  The CoDel implementation was dual licensed BSD/GPL to help the *BSD community. Eric and others have tested CoDel on 10G Ethernet interfaces; as expected, CoDel performance is good in what’s been tested to date.

Linux 3.5 will likely release in August. So it was less than a month from first access to the algorithm (which was formally published in the AQM Queue May 6) to Linux mainline; it should be about four total from availability of the algorithm to Linux release.  Not bad at all :-).

Felix Fietkau Continue reading

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