Monthly Archives: September 2012

Hidden Overhead – how small things really add up

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If you have ever spent some time in the corporate world you may have heard of the word ‘overhead’, and it is generally used to refer to the costs associated with the ‘headquarters’ staff in a large organization. See, you may be the worker on the front lines at the clients’ site, but your hourly rate goes towards your pay, the overhead, and profits for the company. Obviously, the greater the overhead expense the less flexible the company can be in setting rates and still making a decent profit. Now let’s take the concept of overhead to the network world, the two main transport protocols in use in the web are UDP and TCP/IP, one of them comes with more overhead as far as packet size is concerned. So what, why does this matter, it’s just a small bit of data right?

Consider this: What’s a stamp worth? 

Let’s illustrate the fact that small inefficiencies can lead to a large cost to an organization given the frequency of the inefficient action.  Imagine you are in charge of the post office and you need to identify cost savings.

Using the facts below you devise a plan that eliminates an inefficiency that exists with stamps.

  • 1 Pound – 453.592 grams
  • Mail pieces processed in 2010 – 171,000,000,000 [1]
  • Assume every piece of mail (packet) requires one stamp
  • Stamps are printed on paper that weighs 56 g/m(sq) [2]
  • Current stamps have the following dimensions 22.10 x 24.89 mm [3]
  • Assume that we are using first class letters which cost $0.45 cent for the first ounce and $0.20 for each additional ounce. The post office works like airport parking garage, they charge for the full ounce (even if you’re over by .20 grams!).

Now we all know that weight affects postage prices[4], I mean why else would we have those cool airmail envelopes and sheets of paper with the little striped edges, right.

First let’s translate the paper weight so that we have the grams per square millimeter, since we are dealing with the metric system we know that 1m² = 1,000,000 mm², next we divide the weight by the square millimeters to get a weight per millimeter. 453.592 / 1000000 = 0.000453592 grams / sq mm.

The postage stamp is 22.10 x 24.89mm so the area is 550.069 sq mm. The weight per postage stamp is 0.249506897848 grams.

Now we can calculate the straight cost of the stamp in weight added to the letter, we know that 0.249506897848 =  0.0088010968208481997 ounces and that it costs $0.20 cents per ounce, so it costs $0.00044005484 cent to mail the stamp on your letter. Barely noticeable, right? Now let’s multiply that by 171 billion ( 171,000,000,000 ), which is the yearly mail volume; the result, we would be paying $75,249,377.64 just to cover the weight of the stamps on the envelopes. If it was this simple we could use triangular stamps and save 37million dollars!

That’s great but we know that the post office rounds up to the nearest ounce and slaps a $0.20 cent charge on those that go over. Lets test the assumption on varying percentages of letters that could theoretically be put over the ounce limit by the weight of a stamp.

1% of letters are over = 1,710,000,000 * .20 = $342,000,000

This brings me to the last point: quantifiable things matter. You may disagree and many do, however, when you start presenting solutions to problems in the work world there is only one measure that really matters and it comes down to quantifiable outcomes.

To ensure your idea makes it you have to translate these outcomes into dollars, especially when dealing with network speeds, and security issues. Why? For far too long the IT department has sat back and used the ‘security’ argument, which seems to work without any thought to cost (be it in time or money, and more often both) . Your challenge is to sit down and translate your IT related issues into dollars and cents, and come up with quantifiable savings. Remember you can save money by saving time, which is what automation strives to accomplish.

Sources

[1] http://pe.usps.com/businessmail101/rates/weight.htm

[2] http://www.google.com/patents/US5503436?dq=us+post+office+adhesive+stamps&hl=en&sa=X&ei=_AliUKy-GZKo9gSRrYHgCA&ved=0CDoQ6AEwAw

[3] http://about.usps.com/postal-bulletin/2012/pb22330/html/info_006.htm

[4] http://pe.usps.com/businessmail101/rates/weight.htm

Defaulting the extjs 4.1 combobox to the first item in the list

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There have been some very small changes in extjs 4.1 that affect the inner working of the combobox, and actually make it a bit easier to select the first record in the store as the default item in the list instead of just a blank space in the dropdown. (run-on sentences are ok as long as you don’t confuse affect and effect, right?)

To accomplish this task in extjs 4.1 just add the following listener to your combobox:

listeners: {
  boxready: function(){
     this.setValue(this.getStore().getAt(0).get(this.valueField),true);
  // fire the select event ( Event in extjs )
  this.fireEvent('select',this);
  }
},

The ‘boxready’ event (http://docs.sencha.com/ext-js/4-1/#!/api/Ext.AbstractComponent-event-boxready) gets fired once after the component has been laid out for the first time at its initial size. The reason you would use this opposed to beforeshow or render is due to the fact that the combobox will not have a hook into the store until the boxready event is fired if it is initially hidden (say on a second tab, or in a popup window …), and you will get a undefined error running the third line of the code. You will also run into issues if you don’t auto load the store.

A discussion on network cables, throughput and security

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If that title doesn’t get you motivated to read this article nothing will! I’ve been teaching a course in LAN design and it is really theoretical so the things that you need to know always figure that the best case scenario is what you’ll get. So here’s what you absolutely need to know about network cables.

Types and speeds :

Twisted Pair Cable

First, there’s twisted pair copper wire, chances are this is the stuff that connects your computer to the web (unless your’e browsing this from work on a high speed network). Twisted pair takes it’s name from the pattern that the wires have with two wires being twisted around each other to reduce electrical interference from nearby wires. The speeds that can be achieved range from 10Mbps to 10Gbps. This is what you probably refer to as ‘network cable’.

Concentric Cable (Coaxial)

Next, there is coaxial cable, which is also made of copper wire , however, the wires run concentric ( see the image to the left ). This cable is usually used to bring you television via your cable provider, and if you get internet from them then guess what, this is your cable. One thing that always surprises people is that when you use the cable company as your internet provider you ‘share’ the bandwidth with your neighbors. This means that speeds may vary depending on the number of people that are online. Your cable modem that cost you a good deal more than say a regular router actually has to change tour digital signal from the computer into an analog signal to be sent over the shared connection. Speeds with this type of cable are in the tens of Mbps.

Finally we get to fiber optic cables, this is the new kid on the block, as copper wire dates back to the telegraph. These cables are small glass tubes where pulses of light are sent so as you can imagine speeds are very very fast. The speed of light is 3.00 x 10^8 m/s. Let’s put that into perspective, you could travel from New York to Los Angeles (2462 miles) about 75 times in one second (186,000 miles an hour). Of course your data won’t seem like it travels quite as fast but that is due to the various delays a packet encounters on the road to NY or LA depending on where you are at.

Fiber Optic Cable

Now that we got the three main types of wire down consider this … 

So designing a network is like building a nascar car right? It’s all about speed, and being lightweight helps a lot in that area right. A lot of emphasis is placed on the speed of fibre optic cable but let’s not overlook the security benefits of fiber optic cable opposed to cat5 and wireless communication methods.

There are a few things that can happen between the endpoints on a network that could compromise your data. These include:

Tapping - We have all seen those old spy films where someone climbs a telephone pole and taps into the phone wires to listen in on conversations, and we have seen the films where the someone is listening in on radios to intercept messages.

Well, since fibre optic cable is comprised of a bundle of glass tubes, now imagine how hard it is to tap into those tubes without breaking the connection or causing loss that is noticeable.

I dug up this article in the Washington Post that illustrates this with a few interesting stories regarding cables that have been cut during the construction around Tyson’s Corner.

http://www.washingtonpost.com/wp-dyn/content/article/2009/05/30/AR2009053002114_2.html?sid=ST2009053100019

Radiation - You lose data due to interference from electromagnetic radiation, and the amount of resilience you have to this issue is based on your cable choice, fibre optic being the best and twisted pair being the worst.