Well, I have spent the last two weekends trying to set up a lab at home to retest the tutorials for the http://www.linuxhomenetworking.com website. I put it in the garage but needed the test servers on the lab’s switch to connect to my wireless network whose WAP/Router is in my bedroom.

I thought of doing this some years ago, so I bought a Linksys WGA54G game adapter that allows you to connect your Playstation’s ethernet port to your WLAN. I decided to attach the switch to it instead, so that in its “infrastructure mode” I could provide WLAN access to all the lab servers.

Well, I soon discovered that it bridges at layer 3, but at layer 2 it is a little different. The MAC address of all the servers are re-written with a MAC assigned by the WGA54G. This is OK, but the MAC it uses is always that of one of the servers it discovers on its ethernet port. It presents this MAC on both the WLAN side and the wired side. When you try to connect to another server on the wired side the packet gets sent to the server whose MAC address it cloned, not that of the server to which you really need to connect.

I wondered whether putting a single IP address behind it would fix the problem, so I put a DSL router behind it to NAT the traffic from the switch to the WGA54G. I then used port forwarding to get access to the lab servers. Same problem. This makes me wonder whether it also sends traffic on to the LAN using a single source MAC address, not its own, but that of the first MAC address it sees on the WLAN. This is OK for a Playstation, as I assume it only wants to talk to the web, and the first packet it receives will always come from the home router / DHCP server. But in my case the servers were communicating with the internet and my personal WiFi laptop.

I now have purchased a Linksys WET54G on Craigslist for the price of a half dozen submarine sandwiches, and in “infrastructure mode” using MAC cloning, and a fictitious MAC address, everything works fine. It seems to have memory allocated to mapping the rewriting of the source and destination MAC addresses as traffic passes from the WLAN to the LAN.

The cost difference for this extra RAM to store more than 2 MAC addresses? A new WGA54G costs $129 and the WET54G costs $99. The replacement model Linksys WET200G costs $125 list.

My question is why does a device with more functionality cost less? Maybe because they can make more money selling low cost hardware to price insensitive gamers for a small fortune.

Note: If you have a WET54G version 3.1, the version v2.15 firmware of Jun 11, 2007 is notoriously buggy with the WET54G hanging up frequently. Downgrade to firmware version v2.07, Jun 30, 2006 for the version 3.0 WET54G and you should have no problems.
Posted by: Peter | July 1, 2009

How to make Greek style yogurt

Here is a simple recipe I use every two weeks to create Greek style yoghurt.

Tools and Utensils:

  • 1 Salton YM9 1-Quart Yogurt Maker
  • 2 Cuisipro Donvier Yogurt Cheese Maker
  • Measuring cup

Ingredients:

  • 1 quart of pasteurized milk (From supermarket)
  • 1/4 cup powdered milk
  • 1 container of plain yogurt with live and active cultures

How it’s done:

  • Add powdered milk to measuring cup
  • Stir in yogurt into powdered milk, adding milk to smoothen the mixture. With pasturized milk there is no need to sterilize beforehand.
  • Pour mixture into the yogurt maker container
  • Add remainder of milk to container
  • Plug in yogurt maker and cover
  • Wait 9 hours
  • Unplug yogurt maker
  • Put container in fridge to cool for 4 – 8 hours. This will make the yogurt thicker.
  • Pour thickened yogurt into Cuisipro Donvier Yogurt Cheese Makers, cover and place in fridge to strain 1-4 hours depending on desired thickness. You may have to restrain as sometimes the curds as may fall through. Just add the curds on top of remaining yogurt in the cheese maker.

Note:

  • Goat’s milk and goat’s milk plain yogurt have less lactose and will often not be as thick. Use 1/2 cup of powdered milk instead.
  • Warming the yogurt in the yogurt maker for more than 9 hours can make the yogurt very tart.
  • The more fat the milk has, the creamier the yogurt, but the likelihood of creating a tart yogurt increases.
  • After hour 8 in the yogurt maker, test the mixture to make sure it isn’t too tart. Plain yogurts and starter cultures from different manufacturers can cause the taste to vary significantly.

Let me know if you have any comments or suggestions

Posted by: Peter | June 1, 2009

My Experiences in Buying a Custom Bicycle

Let’s start with what I needed; a multipurpose bike that would be comfortable on the short trip to work, longer century rides and local trails. Fenders and panniers are sometimes fitted on commuter models, so it would have been beneficial to have the mounting points for these in the unlikely event I needed them. As my inner serenity is often restored by riding through the steep hills that almost surround my little city I needed gearing to make these climbs enjoyable. However every climb has its decent and I didn’t feel the additional cost, maintenance and stopping power of disk brakes were necessary to stop me rocketing downhill on the return trip home. They can also interfere with the positioning of the panniers I probably wouldn’t use. The caliper brakes used in most road bikes work in dry conditions, but can be dangerously powerless when it rains and on frosty mornings when your fingers lose their strength in the cold. Cantilever brakes became the acceptable compromise solution.

You may not think so, but the stress of bumpy commuting can be severe. Ominous cracking sounds have sprung from my carbon framed Trek Madone with major pothole impacts and so more durable materials such as aluminum or thin tubed steel were preferred. The option of having broader tires for such rough conditions on the road and trails was also critical.

With all these criteria, I settled on buying a cyclocross bike. They tend to be metal framed road bikes with good cantilever brakes and the capacity to fit larger 700x32c knobby or slick tires for both light off road trails and street cruising. With cheaper components they are usually more affordable. I had a Trek 7.3 FX flat handled road bike that met most of the criteria, but I wanted something that would work for both commuting and really long rides. Your body stance on the FX is more upright and is excellent for commuting when you need maximum visibility, but for extended travel the body positioning with most of your weight in the rear can make you get sore after a few hours and that diminishes the fun too much.

I researched all the major brands and their models represented in my neighborhood which all had good reviews. This list included the Cannondale Cross XR, Bianchi Axis, Trek XO, Fuji Cross, Giant TCX, Lemond Poprad and the Specialized Tricross. They were all very similar in geometry and components for my criteria which were based more on functionality than form or weight. The disappointing thing was that it appears that the manufacturers focused on cyclocross frames in the mid range sizes as not all have models in the largest 60cm – 62cm sizes.

I admit that I don’t like visiting bike shops to buy bikes. It always get an intimidating feeling in which I suspect I’m going to end up getting something that I don’t want at a price I can’t afford. In my bikely wisdom “Beware of ego and money for they will conspire to deceive you.” So I usually leave the pride at the door and spend a lot of time trying to understand what I need and what they want me to buy. I have been generally disappointed with my bike purchases because I am tall and long limbed with the largest frames often being too small. This becomes apparent not in the store when the accommodating sales representative’s compliments and minute technical adjustments appeal to your gullibility. It happens when you ride. If you feel any stress at all on your knees or wrists beware as it could lead to pain later on. Never rush a bike purchase it will always be there next week.

In this cyclocross case, the wisdom of waiting really paid off. After visiting many stores, testing many models, extending many seat posts and talking about longer stems, I began to feel something was wrong. When the sales team says too many, “Ahhhhhs” and “Hmmms”, followed by “well that’s the biggest we’ve got” you know you need to start a different kind of hunt.

A frame that is a little too small may not be a factor for the casual rider but I ride 30-100 miles per week and I really didn’t want to have any regrets for my specific needs. My Madone has a comfortable ride. It is light and responsive, and very comfortable when my hands rest on the brake hoods in an upright body position. The situation changes when I have to ride with my hands in the handlebar drops as my wrists sometimes ache. Pressing the brakes can also be difficult and stability gets noticeably worse especially at high speeds of 35 Mph and above.

With a clear idea of what I did and did not want, I decided to visit a Giant bicycle dealer. This was done on purpose as they sell no really big frames at all and I wanted to find out what they do when customers needed something larger. They told me to try a custom frame. I must admit I had heard of people getting custom bicycles costing $3,000 to $5,000 made by local craftsmen and I thought it was extravagant, but I was curious and I strongly suspected that I needed something unique. I certainly wasn’t going to find a second hand bargain on Craigslist.

I visited Bronson, the owner of Silva Cycles on Valentine’s day in the middle of a California downpour with my wife’s roses, delectable chocolate bonbons and a card whispering “I Love You” patiently waiting on the back seat. The workshop was one of many businesses hiding behind identical roll away shutters located in a u-shaped commercial building with its parking lot in the middle. He was there with an electrical crew fitting a huge circuit breaker for a fire breathing arc welding unit lurking in the corner. There were bike drawings everywhere, neatly rolled up or laid out on the few work benches. A wine rack or a honey comb must have been the inspiration for the architectural handiwork that housed hundreds of tubes. Bike frames hung from the roof. It was damp outside, but the small room was comfortably warm.

“Querido amigo” are words used to describe a friend of great importance, “pinche breaker” on the other hand signifies the wiring work must be delayed. Profound discussion followed in eloquent spanglish and eventually it was decided that the rain, Sunday supplier closing hours and of course, Cupid, would make the work drag until Monday. It was then my turn.

The explanation of my predicament spread a knowing smile across his face and each nod of understanding was reassuring. Of course I had to hear the sell job. His use of quality components, the light weight stealthily tapered tubing with walls that were thick at the end but not in the middle, the art and science of bike building, the benefits of lugged versus welded construction, the philosophical paradoxes of carbon, steel, titanium and aluminum and finally the computer system that would casually spit out the ideal dimensions making mere spreadsheets weep. The execution was admirably genuine, mutedly enthusiastic and done by a craftsman who clearly knew his trade.

I too was clear. Make it simple. Shimano 105 components, but I could splurge for the smoother shifting Ultegra. No fancy paint, lugs, handle bars, seat posts, or wheels. A steel frame would be heavier, cheaper and just fine. I needed a big fat mountain bike cassette in the back and a standard road bike triple crank up front so I could speed downhill and breathlessly recite poetry while riding up Mount Everest with enough energy left over at the top to do the “Macarena”. The wheels had to fit tires that would chuckle at potholes and make bent nails flee in terror. He had to do it all within the midrange road bike, top end cyclocross bike $2.0K to $2.5K price bracket. Simple? Yes, simple.

The ballet of getting a bicycle fitting is as intimate as going to a tailor to get measured for a suit, but at the same time more dangerous because most of the readings are made with spring loaded telescoping wooden sticks. Needless to say I shouldn’t have worried, none of them could pop out enough and I was especially thankful that the inseam tool was too short. He eventually gave up and began using string and a ruler instead. The computer was going to need a coronary bypass.

He measured the distance from my neck vertebrae to the center of my fist at the end of an outstretched arm, my inseam, the height of my collarbone from the ground, my shoe size, my height and my weight. I even had to rush home to pick up the Madone so that frame could be measured too. There were some more questions, and a few emails later in the evening I made a deposit through Paypal all in time for the candlelight dinner with the family.

Here is a good video about what I went through to reach this stage.



There was to be a three month wait. I figured four months would be more likely from this one man show, but he surprised me with the precision of his prediction. I ride a lot, but I really don’t tinker with my bike because I know the damage I can do, so the next set of questions had never crossed my mind before. What model cassette, stem, seat post, brakes, saddle and handle bars? In a very polite tone I would sort of say, “You choose, as long as it comes up under budget.” What color frame and bar tape? Now, that I could deal with.

The bike is no beauty, it is versatile and utilitarian as I was more concerned with fit and value versus cosmetics. It is heavier than the Madone, but my wrists don’t ache and I can do the “Macarena” any day.

I really don’t think a custom bike is required for the casual rider with average height and bodily proportions for whom mass produced frames are made. If there is a hole in the ego that needs filling or you genuinely like to tinker then it may be worthwhile. I can’t speak for mountain bikes as I am not active in that area, but I could easily imagine heavier road cyclists considering a cyclocross bike with larger 700x32c tires and its more forgiving gearing as a viable alternative to a carbon framed model. If you have unusually long or short arms or legs, and you have been disappointed with a number of past purchases then, based on my experience, a custom bike is the right thing.

I am proud to say that I am happy with my custom bicycle and that the bonbons were equally appreciated too.

If you have any comments, please let me know.

The priority given to information technology operations and the culture of the staff that supports it is often quite different when comparing companies which earn a majority of their income from the Internet and those that don’t. Here is what I have tended to notice.

From the day of their creation, web companies rely on IT as a key foundation to their business, usually with limited budgets. The IT employees tend to have range of skills and are more likely to embrace open source tools from the beginning, not always by choice, but by necessity. The external customer facing applications are usually internally developed and as a result internally created tools for monitoring and graphing is often the norm. Risks are taken to speed the deployment of new features and reduce costs.

In the more traditional enterprises, the approach is very different. The environments are more static and the applications are often packages developed by external parties to automate well known business processes. Maintenance is therefore done my vendors who promise stability. As a result, the IT operations staff tends to spend more time managing vendors and their contractors. This reduces the IT department’s scope of influence, their tolerance to risk and the range of technologies to which they have hands on exposure while simultaneously increasing their tendency to have more specialized skills.

These are two very different cultures. As web companies grow and the tolerance for lost service, planned or unscheduled, decreases, the need for a blended mindset increases.  The need for subsystems to function independently of one another also increases in order to reduce the risk of cascading or bottleneck types of failures.  The organizational challenge of deciding what the cultural blend should be still remains.  Not just overall, but also on a per-application and physical subsystem level and should be an ingredient in defining risk tolerance profiles especially when considering disaster recovery strategies.

Posted by: Peter | April 4, 2009

The Knowledge Trap

Fast growing technology organizations need to be constantly aware of the difficulties it places on their staff and their emotional well being. A common problem is the knowledge trap in which the persons who create a design, implement a project or develop a tool become the in house experts in that area. This is normal in many organizations, the difference with fast growing companies is that there is often insufficient time to complete the documentation, monitoring and hand off phases of the project. This leads to staff being overworked not just on current projects, but also on the ghosts of previous work.

At first this can be welcomed by the team members as their knowledge provides some degree of status, but as time goes by, the lack dispersed knowledge can lead to departmental frustrations and resentment. Key staff members soon don’t have time for lunch, vacations, or even sleep. They become trapped by their own success. Always be on the alert for statements which imply persons are not taking the initiative to understand a particular system that someone else developed. It is often a clear sign that documentation and cross-training needs to be immediately reviewed.

Innovative freedom leads to new and wonderful ways of doing in web site design and vision, but with tactical maintenance and support, discipline is freedom.

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