Archive for the ‘OLPC’ Category

I’m attending the International Summit for Community Wireless Networks

September 24, 2012

I will be giving a updated version of my bufferbloat talk there on Saturday, October 6.  The meeting is about community wireless networks (many of which are mesh wireless networks) on which bufferbloat is a particular issue.  It is in Barcelona, Spain, October 4-7.

We tried (and failed) to make ad-hoc mesh networking work when I was at OLPC, and I now know that one of the reasons we were failed was bufferbloat.

I’ll also be giving a talk at the UKNOF (UK Network Operator’s Forum) in London on October 9, but that is now full and there is no space for new registrants.

Bufferbloat in 802.11 and 3G Networks

January 3, 2011

Any network system with buffering shared among many users is much like a
congested highway.  We’ll call them
“big fat networks”. Two such network technologies which show this problem are 802.11 (abgn), and 3g wireless.  In one, the buffers are distributed among the clients (and may also be in the access points and routers); in the other, both possibly in the clients, and the radio controllers they talk to, but also possibly in the backhaul networks.

You have suffered unusable networks at conferences.  Wonder why no more. You can make your life less painful by mitigating your operating system’s and access point’s buffering.

Moral of the Story

Whether you call what we see on 802.11 and 3g networks “congestion collapse” as the 1980’s NSFnet event was called (with high packet loss rates), or something different such as bufferbloat (exhibiting much lower, but still significant packet losses), the effect is the same: horrifyingly bad latency and the resulting application failures. Personally, I’m just as happy with “congestion collapse” as with bufferbloat.

The moral of the story is clear: when the network is running slowly, we really need to absolutely minimize the amount of buffering to achieve anything like decent latencies on shared media. Yet when the network is unloaded, we want to fill this network pipe that may be hundred megabits or more in size. On such a shared, variable performance network: there is no single right answer for buffering. You cannot just “set it, and forget it”. Read on…


First post after a long absence. (and a Rant!)

May 15, 2008

Life’s been a bit crazy, including shipping a machine, and being in the clutches of a surgeon several times.  So I’ve not been blogging….

Here’s this morning’s rant: I just installed Kompozer (formerly nvu) to edit some html.  Here we are in 2008, and I still find that KDE and Gnome aren’t sharing simple settings; I end up with a different font on my screen.

Hey, folks, don’t we care about what people think who don’t care what project the application comes from, but are just looking for good tools to use?  I really don’t want to have to go find what magic knob to twist; I’ve already twisted one knob to my satisfaction… Let’s get together, all…

My other rant are for spammers and crackers…  Evil behavior, indeed. Someone broke into my home server. As time is short, I’ve decided to move my web log to to here where others can maintain the software for me; someday I’ll upload my old postings….


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