Bigbro's foray into the scary world of blogging
17 02 2007
Modern networks are converging on an IP transport, with voice, video and data traversing the same networks. This gives us a cost saving and complexity saving, but introduces other problems such as jitter, latency and packet loss. QoS allows 'selective unfairness' to be applied to packets traversing a router - EF (Expedited forwarding), AF (assured forwarding) and BE (Best effort) type classes are generally available. There's no such thing as a free lunch, some traffic is going to have to suffer - and there is often a political or administrative issue in deciding exactly what traffic should be put in each class.
Network monitoring (mrtg, cacti, etc.) gives us some view of how the network is looking, but doesn't give us an indication of what effect micro-bursts and short-lived traffic patterns are having. This is what the Corvil Bandwidth Quality Manager attempts to model. By getting a copy of real traffic (from a span or tap port) and building up a virtual model of the network in software, the system can make some estimates of the expected latency. Not only that, but since it's a virtual model in software, what-if analysis can be performed.
posted at: 16:39 | path: /technical | permanent link to this entry
Huge thanks to Sarah and Sorcha for helping with the recordings at SkyCon. Most speakers have agreed that their talks be made available on the internet. Some are already up in rough / raw recorded form. I will clean them up and recompress soon, but for the moment recording the remaining talks is the priority.
posted at: 15:31 | path: /technical | permanent link to this entry
Bill O'Brien came to speak on Microsoft's source, their attitudes to open source and free software, and how they integrate with other vendor products and F/OSS products.
There's a huge body of people who contribute in a very valuable way to the Open Source community, but they don't code. Alan Cox detailed some of the roles that these people play and how they make a contribution that is every bit as valuable as the people who write the code.
Mikael Fernstrom showed some of the projects that have been implemented in the University of Limerick. PD allows things like a virtual Bodhrán to be prototyped and built - various sound effects, including multi-tones (like the ever rising / falling note) to be generated and something like the Tap-O-Meter to be made. The Tap-O-Meter was a real-time counter for James Devine, the fastest tap dancer in the world, to measure just how many taps per second he was able to achieve. PD allowed changes to be made quickly and with recompiling code, which makes debugging and interactive composition to take place.
Interactive sonification type projects like Squiggle and Celeritas used PD to generate audio from various sensors - and in general can be used to create audio from any data input. This provides huge flexibity and massive scope for fun, judging by some of the videos Mikael showed of IDC (Interactive Design Centre) students and staff.
Something like Max/MSP is almost becoming stale, since all the new exciting developments are happening in the open source world. PD is implemented in C, and the source code is available - so the only limitation is our imagination.
Jono Bacon travelled to Limerick to deny any and all rumours regarding his preferences for aquatic marine fowl - though he felt the nice picture of Alan Cox with a lake full of ducks in the background added something to his presentation. Despite the early hour and it clearly being the morning after the night before, an excellent presentation centring on 'Community' ensued.
Community, Governence (Be excellent to one and other) and localisation are the keys to making Ubuntu the successful distribution it is today. With over 8 million users, applications getting better and better all the time and a very successful and still growing community, Ubuntu is going from strength to strength.
As an example of the translation and localisation effort, Jono cited Jokosher being added to Rosetta (the Ubuntu translation tool) and being available several weeks later in 12 languages.
