I am a bit of an automotive enthusiast, so when I’m not working, I do spend a fair amount of time browsing automotive websites. I, like many people in the hosting industry, crave information. I like hearing about new design directions, emerging technologies, and past stories about others’ experiences with their vehicles. While browsing, I came across some images of the guts of a BMW that had gone in excess of 60 thousand miles without an engine oil change. Needless to say, the internals were slathered with a gummy sludge and the engine was ruined.

Many technologies we use these days have become so common place and are operationally intuitive enough that we are often able to figure them out and use them without ever having to crack open an owner’s manual. I bring this up because, many technologies in the hosting industry follow suit. There are a number of developers who create software that is designed to make it easy to host websites. They are marketed as the only solution you ever need and, in some cases, imply that all you need to know is how to use a web browser to successfully host websites, not only for oneself but a plethora of other clients too! The servers run themselves, and you only need to spend a few minutes setting your clients up! It’s like free money!

Unfortunately, as the owner of the previously mentioned BMW found out, this is not the case. There are a lot more things going on behind the scenes than just seats and a steering wheel, as are the same with servers. On occasion, we receive support tickets that just say “the site stopped working.” In an attempt to gather more information, we will often ask the client a wide range of questions that help us find the problem faster and come up with the best possible solution. However, sometimes the answer from the customer is, “I haven’t touched or logged into the server in days/ months/ (hopefully not) years.” The more relevant metaphor for this is, “I haven’t changed my BMW’s oil in years!” Servers are like any other complex machine. They require constant maintenance. This includes: updating anti-virus definitions, monitoring bandwidth usage for anomalous spikes, rotating logs out if they are getting too large (provided some other rotation scheme is not already in place), keeping an eye on disk space usage, and creating a disaster recovery plan and backups. So take some time, get to know your server, and familiarize yourself with good preventative maintenance techniques. Your server, your clients, and your BMW (if applicable) will love you for it.

I just got off the phone with my father. Actually, I got off the phone almost 24 hours ago, and I’m just now becoming calm enough to write clearly about it. My father had a problem: he was attempting to use a computer without supervision. Now, my father is a smart man. He has a master’s degree from Harvard, he has “A Brief History of Time” on his bookshelf, and he consistently left clicks when I ask him to right click. The exact nature of the phone conversation is boring an unimportant, except for one thing. My father needed at one point to save a document in MS Word format. Since he has a Mac, he created the document in Pages. He insisted that his efforts had been wasted since (he claimed) Pages was unable to save in MS Word format. I tried to convince him that it could save not only in MS Word format, but roughly 15 others, but he was unrelenting. Finally I got him to check in the Export menu “to humor me,” and lo and behold, that’s where all his Microsoft formats were hiding. Why do people ask geeks for help, then insist that the help provided is incorrect?

I am expecting to spend at least half of my Christmas visit fixing their multiple computers, synchronizing their files, uninstalling the spyware they were tricked into installing, and generally explaining to them that no, the computer cannot just “know what you want.” And at every turn, I expect to hear dissenting opinions and accusations that I am somehow “hurting” or “confusing” the computer by what I’m doing.

My fellow computer geeks all across the country will also be making that periodic tech support pilgrimage. Just talking to the other programmers in the office I’ve discovered quite an arsenal of tools that they will be bringing with them. From special screwdrivers and thumb drives to entire operating systems and (in one case) a whole new computer, we go into the holiday season armed and ready to set ourselves up for future tech support calls.

Some of my more memorable tech support calls have been from relatives, usually helpless in the basic skills necessary to diagnose the problem over the phone. My aunt made one historic call a few years ago. They had just gotten cable internet in their small country town, and after a week or so she was having problems connecting to the internet. So after hearing about the problem I told her I was going to need her to look at the modem. We spent the next few minutes arguing about whether or not she had a modem, and whether or not the problem could have been caused by never having a modem in the first place. After concluding that she did have a modem, and it was still where the technician left it (under the sink, good one technician! bravo sir!), I asked her “what do the lights on the modem look like?” A valid question I thought, and a relatively simple one. I was expecting to hear a short list of the lights’ labels and whether or not the light was lit. What did I get? “Well, they’re about a quarter inch wide and about a sixteenth of an inch…no…make that about three thirty-seconds of an inch tall, they’re spaced about a half an inch apart…why are you laughing!?”

Another fond holiday memory is the argument I got into with my grandmother. She wanted to “get a house page on the wide world web.” I managed to correct her to “world wide web” without offending her, but then the real fun started. She claimed that “the world wide web is better than the internet!” I tried to explain to her that web pages were only a very small subset of the internet, and that the two terms really didn’t describe the same sort of thing. She decided to put it to a vote. Proudly marching into the living room she announced to the 40-so gathered people “raise your hand if you think the internet is better than the world wide web!” They all stared blankly at her for a short time. Sensing victory, she turned to me and screeched “SEE!?” and stormed out.

So this year I will gather my toolkit, my extra networking cables, my CDs with avg antivirus, firefox, spybot, hijackthis, and zone alarm, my copies of windows XP and Mac OSX, two different linux live CDs, my thumb drives, and my overworked laptop, and make the trek down to my parents house. Please, if you are reading this and you didn’t recognize the items in that list, do yourself and the geek in your life a favor: Find out what operating system you run* and go out and buy yourself the “For Dummies” book that corresponds to that operating system. That can be your gift to your geek this year. Show them that you own the book that holds most of your answers, make a promise to them to at least open the book before you pick up the phone, and you will see what it’s like when someone experiences holiday joy.

Plus, you might learn something.

*Look at the top left corner of your screen, if there’s an apple there, proceed to “Apple”. If not, look at the bottom left. If there’s a start menu, proceed to “Windows.” If there’s neither, pick up the phone and call the person who works on your computer and ask them.

Apple: Click the apple, and go down to “About this mac.” There should be an entry on the first screen called “Operating system.” That’s the operating system you have, you’re done.

Windows: Click the start menu button and look at the left side of the start menu. Your operating system may be listed along the left side. If there isn’t, hold down the windows key on your keyboard and press the “Pause” key (you never use it, it’s in the top right). A window should come up that says “system” at the top. Your operating system will be the first item under “system”

As I watched the Dallas Cowboys dismantle the Green Bay Packers last Thursday night, I noticed an ever so slight – almost invisible – passing of the torch from Brett Favre to Tony Romo. It became quite clear – Football is a young man’s game.

As I sat and pondered what that must feel like for Brett and his crew, I noticed frightening similarities between hosting and football. Hosting appears to be a young man’s sport as well.

Now, before you guys (there I go again) pile on and beat me down – hear me out. I am not saying that Brett and his older brethren are washed up and incapable of playing football – but I am saying, their primetime has passed and any future success should be considered borrowed time on a great career coming to conclusion. Facts are facts – professional football is a very physical and mental job and the youth + skill appears to outweigh age + experience.

This leads me back to hosting. A world full of very young and extremely talented players. An industry where degrees and certifications come in a distant second behind skill and innovative thinking. I often find my thirty-something (barely) resume on-the-line with both new and old competitors. I can assure you, the young competitors terrify me, and the older ones typically bore me.

The recent interviews for potential new hires here at SL are eye-opening. Young Guns coming out of high school with Cisco Certs, college students working on cutting edge technologies and of course – the prodigy that shows up from time to time who was born to design and innovate beyond all our wildest dreams.

I often tell Mike, our CFO, that technology is changing the rules of business and how things will be done going forward. In Mike’s accounting world, graduates come out of college with lots of book knowledge and very little experience and gain experience over their career. In the technology world, I would argue the younger talent holds more technical knowledge (book or real world) than the older more established crowd What I bring to the table is business and technical experience; but I find myself learning more and more technology from my younger team members everyday. It’s a never ending battle to stay on the leading edge – but I wonder – how long will it be before I hand the torch?

Go Cowboys!!

“ah – I don’t need backups.”
“Too busy to do backups – I’ll get to that later.”
“Backups? It costs too much.”
“I don’t need backups – MTBF of a Raptor is 1.2 Million hours.”
“Oops – I forgot about doing backups.”

Backups are one of the most commonly forgotten tasks of a system administrator. In some cases, they are never implemented. In other cases, they are implemented but not maintained. In other cases, they are implemented with a great backup and recovery plan – but the system usage or requirements change and the backups are not altered to compensate.

A hard drive really is a fairly reliable piece of IT equipment. The WD 150GB Raptor has a rating of 1.2 Million hours MTBF. With that kind of mean time between failures, you would think that you would never have to worry about a hard drive failing. How willing are you to take that chance? What if you double your odds by setting up two drives in a RAID 1 configuration? Now can you afford to take that chance? How willing are you to gamble with your data?

What if one of your system administrators accidentally deletes the wrong file? Maybe it’s your apache config file. Maybe it’s a piece of code you have been working on all day. Or, maybe your server gets compromised and you now have unknown trojans and back doors on your server. Now what do you do?

Working in a datacenter with thousands of servers, there are thousands and thousands of hard drives. When you see that many hard drives in production, you are naturally going to see some of them fail. I have seen small drives fail, large drives fail, and I have even seen RAID 1 mirrors completely fail beyond recovery. Is it bad hardware? Nope. Is it Murphy’s Law? Nope. It’s the laws of physics. Moving parts create heat and friction. Heat and friction cause failures. No piece of IT equipment is immune to failure.

That 1.2 million hours MTBF looks pretty impressive. For a round number, let’s say there are 15,000 drives in the SL datacenter. 1,200,000 hours / 15,000 drives = 80 hours. That means that every 80 hours, one hard drive in the SL datacenter could potentially fail. Now how impressive is that number?

Ultimately, regardless of the levels of redundancy you implement, there is always a chance of a failure – hardware or human – that results in data loss. The question is – how important is that data to you? In the event of a catastrophic failure, are you willing to just perform an OS reload and start from scratch? Or, if a file is deleted and unrecoverable, are you willing to start over on your project? And lastly, how much downtime can you afford to endure?

Regardless of how much redundancy you can build into your infrastructure with the likes of load balancers, RAID arrays, active/passive servers, hot spares, etc, you should always have a good plan for doing backups as well as checking and maintaining those backups.

Have you checked your backups lately?

“You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat.”

— Albert Einstein, explaining radio.

Email, like Telephones, the Internet, Power Lines, Credit Card Terminals, ATMs, etc. have become so much part of our daily lives that we just accept it without really thinking about it. You click “New,” put some data into a form, then click “Send.” In a couple of seconds (minutes if your mail servers are suffering a spam blizzard), your LOLCAT Email has zipped from one end of the Internet to the other (This proves that, unlike radio, Email does have a cat). Do we marvel at this paragon of technology? Not really. I generally grumble at the mixed blessing that has brought me spam.

A while back, I made the mistake of reading the Wikipedia article on the Power Grid. I was amazed at the mechanics of the system that allows a handful of uranium melting itself into slag in Glen Rose, Texas to shove electrons across a couple hundred miles of copper, through a handful of coils… all to be stopped by a little switch in my wall before they could excite the gasses in my Compact Fluorescent light bulbs. For two weeks after that, I was a road hazard. In the middle of my commute, I’d glance at my right hand mirror, gaze out my side window, and think “Hey! I didn’t know they were running two phase power out here!” I must say that I couldn’t have been a more dangerous driver during those two weeks if I was dryping.

My latest project at SoftLayer (WHOIS management for ARIN… look in the portal under SWIP) had me doing research on Email (as all transactions are conducted through Email).

Like David Bowman staring into the black monolith at the end of 2001, I was struck by the simplicity and beauty of the Email system!

Let’s tag along with an Email message, so you can see just how cool this is.

Bob is currently taking a vacation in Glen Rose, Texas (taking the tour of the Nuclear Power Plant). Sitting in the lobby of the Visitor’s Center (thinking about this giant reactor being at the beck and call of his little switch), he has a firm wish that Alice could come see this. He’s a cheapskate, though, (that’s why he’s at a local power plant instead of, say, Disneyworld) so he’s not going to waste money on a Power Plant Postcard and stamp at the gift shop. No sir, he opens up his blackberry and sends a short Email to Alice (”Wish you were here!”). A few seconds later, Alice’s Email client pops up an alert that she’s received an Email from Bob. The Email itself is simply a block of text… really! No magic going on here! Here’s what the Email looks like:

From: bob@example.net
To: alice@example.com
Date: Wed, 10 Oct 2007 12:54:08 -0400 (EDT)
Received: From EXAMPLE.NET
 by EXAMPLE.COM with SMTP
 Wed 10 Oct 2007,
 12:55:00 -0400 (EDT)

Wish you were here!

---
Bob
Sending to Alice for over 30 years.

Simple, huh? To help visualize this transaction, Figure 1 shows a “RFC 2822 Compliant Post Card:”

Bob opens up his Email client, and writes “Wish you were here!” in the message area. He then adds his signature, and writes in the subject. The Email client adds headers to the address area of the Email (From, To, and Date), then drops the Email into Bob’s local Email server (EXAMPLE.NET).

The Email server at EXAMPLE.NET looks at the address section of the Email and notices where it is to be sent to Alice (who has an Email box at EXAMPLE.COM), and opens up a SMTP (Simple Mail Transfer Protocol) connection to Alice’s mail server. It then sends the message and moves on.

Alice’s Email server puts a “postmark” header on the Email (the Received header) and drops a copy of the entire text block into Alice’s Email box.

Alice opens up her Email client, which then downloads all the text files from her Email box. It reads the From header and tells Alice that she has an Email from bob@example.com

That’s it! Simple, huh?!?

If Bob’s Email server can’t send the mail directly to Alice Email server, it can send the Email through a relay server. This server adds its own “Received header” to the Email. If you look at the headers of any Email you’ve received (spam is not only a good source of vitamin Sodium Nitrate, but also an excellent resource for Email headers), you can see every single server your Email passed through. It’s like those neat stickers customs officials stick to your luggage as an apology for cracking your locks when you fly internationally.

That’s all there is to it! A simple block of text, passed off to an Email server. And the actual protocol is just as simple. Here’s what the communication between Bob’s Email server and Alice’s Email server looks like (modified from the example on Wikipedia’s SMTP article):

Bob’s server connects to Alice’s and identifies itself:

ALICE: 220 smtp.example.com ESMTP Postfix
BOB:   HELO example.net
ALICE: 250 Hello example.net

Bob’s server then tells the receiving server about the Email:

BOB:   MAIL FROM:<bob@example.net>
ALICE: 250 Ok
BOB:   RCPT TO:<alice@example.com>
ALICE: 250 Ok

Bob’s server then tells Alice’s that it’s ready to send the real message:

BOB:   DATA
ALICE: 354 End data with <CR><LF>.<CR><LF>

Next follows the RFC Compliant Email message from above, ending the data with a “.”, which tells Alice’s server that Bob’s message is complete:

BOB:   From: bob@example.net
BOB:   To: alice@example.com
BOB:   Date: Wed, 10 Oct 2007 12:54:08 -0400 (EDT)
BOB:   Received: From EXAMPLE.NET
BOB:    by EXAMPLE.COM with SMTP
BOB:    Wed 10 Oct 2007,
BOB:    12:55:00 -0400 (EDT)
BOB:
BOB:   Wish you were here!
BOB:
BOB:   ---
BOB:   Bob
BOB:   Sending to Alice for over
BOB:   30 years.
BOB:   .

Alice’s server lets Bob’s know that the message is queued to go, and Bob’s server signs off:

ALICE: 250 Ok: queued as 12345
BOB:   QUIT
ALICE: 221 Bye

I marvel at this technology. Every Email in the world is transmitted by this simple protocol. The whole of electronic communication takes place by handing small blocks of text from one Email server to another, until it finally makes its way to the recipient’s inbox. That’s all! No magic potions, no hocus pocus, no tying messages to carrier pigeons or pulling cat tails.

Not only this, but your message is flying through a blizzard of spam. Because the protocol is so simple, people build simple tools that blast out millions of messages at a time, flying all over the Internet. But the awesomeness of this just makes Email that much more awe inspiring. Email has been running, nearly uninterrupted (as a whole) for DECADES under the most concerted distributed denial of service attack of all time.

And STILL your Email gets to its destination. Benjamin Franklin would be proud.

Think of this the next time you forward the latest list of funny jokes to everyone on your Email list. This incredibly simple protocol will make sure that your vital Email gets to every recipient listed! “Neither snow, nor rain, nor heat, nor gloom of night stays these couriers from the swift completion of their appointed rounds…”

That is a heck of a strange title for a hosting company blog post.
It was, however, a great title for a Master’s thesis. Bear with me though and I’ll put it together.

Once upon a time, I spent many a day (evening, night, whatever) in the basement of the Bright building at Texas A&M blasting ultrasonic waves at samples of composite materials and measuring the energy output on the other side. What we found was that if you hit the right frequency that made the little particles resonate, then a lot more energy was transmitted through the material¹. But sending a lot of energy at the wrong frequency didn’t do any good at all and most of the energy was absorbed. After a while, using the experimental data, we learned how to predict what frequencies transmitted the most energy.

Developing projects for a hosting company is pretty much the same. You can spend a lot of energy writing code and developing products, but if you don’t produce something that resonates with the customer, no matter how much energy you put into it, you aren’t going to get the results out of the other side. Having been in software development in the hosting industry for quite a while now, I have worked on projects that resonated with customers and a unfortunately on a few that didn’t. The trick is to collect enough data before you start by using a mix of experience and customer interaction to predict what will resonate, and what won’t.

See, I brought it all together and I get to tell myself that I still use my master’s degree.

¹I way oversimplfied this. My apologies to Dr. V. Kinra.

Globalization is now, and forever will be, an ubiquitous topic in most political, economic, and social forums. The term “globalization” is defined by Merriam-Webster as “the development of an increasingly integrated global economy marked especially by free trade, free flow of capital, and the tapping of cheaper foreign labor markets.” The latter of the traits has emerged as the strongest point of contention due to outsourcing. Markedly, Fortune Magazine recently published a story on a new “insourcing” trend. It’s a trend so new that my spellchecker doesn’t even recognize the word.

Though “free trade” and “free flow of capital” are explicitly declared in the definition of globalization, free flow of information is somehow absent. The role that the Internet has played in globalization and the development of the global economy cannot be overstated. Continued advancements in the Internet and Telecommunications have literally connected suppliers, vendors, sellers, and buyers that historically had been segmented by barriers such as geography and time zones. What this phenomenon has come to shape is the global marketplace, where products from across the world compete for the preference of an endless consumer base. With an increase in competition comes an increase in the consumer expectations for quality and performance. As a growing company with a significant international client base, SoftLayer continues to strive towards providing quality solutions and support that exceeds our customers’ expectations.

Though the Internet has helped to fuel the soaring growth of the global marketplace in the recent decade, there are still many obstacles that impede its progression. Most of the hazards have a legal connotation surrounding hot-button issues such as Intellectual Property, Copyright Infringement, and most notably in the hosting world, Abuse (bandwidth theft, computer viruses, fraud, etc.). It’s certainly enough to keep our abuse department busy as international standards and governing policies are fortified to help combat these areas of concern.

This observation merely skims the surface of globalization and the development of the global economy as there are many arguments both for and against its advancement. At the forefront or behind the scenes (depending on your vantage), you will find the Internet. It has been stated that “the Internet is the backbone of the global economy” with evidence cited in the form of web transactions going from “virtually nothing in 1994 to nearly $657 billion in 2000.”¹ Care to guess what that number is now? As Softlayer furthers its commitment to quality, our objective is to continue to strengthen the platform from which our domestic, international, and multinational customers launch into and compete in the global marketplace.

¹Charles W. L. Hill, International Business: Competing in the Global Marketplace (Irwin/McGraw-Hill; Fifth Edition, 2004), p.13.

I once ran across an article that said Equinix customers can access over 90% of the world’s internet networks and users due to the number of carriers, content providers and peering located in their IBX facilities. That is a very staggering thought if you really think about it. The Internet is an endless array of fiber spread across the globe and most of it touches an Equinix facility somewhere along the path. There is little doubt about the value in being located inside an Equinix facility. The world’s largest carriers have standardized on using their facilities as global POPs to reach anyone and everyone connected to the net

While reading Mark Cuban’s latest blog, he proposes using an IntraNet vs the InterNet for large scale application deployment. He basically outlines the inability to sustain high bandwidth quality of service across the public internet. He believes that if the hosted application were to reside on the same network as the end user, the probability of success would be greatly enhanced. Although not quite the traditional IntraNet as we know it today, I do agree that having the content and user on the same network will probably lead to a much higher quality of service.

Taking that thought process and merging it into the latest Web2.0 initiative creates interesting possibilities. Isabel Wang has very provoking thoughts on social networking, SaaS, grid technology, EC2, S3, web integration and an endless list of possibilities. SWSoft and VMWare are talking SaaS and virtualization integration. Vlad and his team at 3Tera are deploying grids like there’s no tomorrow and Facebook, Salesforce, and Amazon are now building apps on an open API system designed to cater to developers. The whole world is reaching out to interact, merge, integrate, build, piggyback, and coordinate technology to make the geek world user friendly.

So I come back to SoftLayer and think – where do we fit into this big picture. It seems our network-within-the-network approach appears to fulfill Mark Cuban’s desire for both Intranet and Internet. The ability to rapidly deploy dedicated, virtualized, and grid technologies at the click of button serves the fundamental need of the Web2.0 entries. The ability of these companies to interact/integrate publicly and privately among each other is well served through our customer exchange. It sounds like if we were to strategically drop SoftLayer PODs inside the Equinix’s of the world – we could bring the world a much needed service for the future. On network Application exchanges to your local IntraNet. Now, there’s an idea.

In previous posts, there have been mentions of the datacenter of the future, kvm over IP and a reference to an elevator. Then, just the other day, someone in the office pointed out this article: “How remote management saved me an emergency flight overseas”

The article discusses the successful deployment of servers from a remote location. The author talks about being able to remotely configure and deploy some new servers from the confines of a ski lodge. Of course, they had to have someone at their offices to receive the server shipment, unbox the servers, rack them up, get them all cabled, make sure space, power and cooling would all be sufficient and then put in a CD. Things that weren’t mentioned probably included throwing away all of the packaging material, doing QA on the hardware to verify it was all correct and changing any BIOS settings.

Beyond all of that, there are many things that are just inherent to the process that they didn’t refer to, including having to find the right server vendor, negotiating pricing for the servers, making sure all of the pieces and parts were going to be shipped, tracking the shipment dates, contacting the vendor multiple times to try to find out why the shipment wasn’t going to be on time, having available datacenter space and infrastructure, putting those dang cage nuts in the server racks, having available switch ports, making sure the network was configured correctly, providing network security, making sure all of the software licenses were up to date, etc, etc, etc.

Or, as so many of you already know – they could have gotten their servers from a dedicated hosting provider such as SoftLayer (hint, hint) and had the servers purchased, configured, QA’d and online within just a couple of hours and with no more effort than just filling out a signup form. It’s hard to imagine there are still so many people out there doing things the hard way.

The Open Systems Interconnection Basic Reference Model (OSI Model) or 7-layer model has been around for decades. It was actually developed in 1977 by the ISO as an abstract model of networking protocols which is divided into seven layers. Each layer interacts with the layer beneath it or above it depending in the directionality of the conversion. The 7-layer model was written from a broader point of view and in today’s world is not really used as it was intended. The most common protocol and the one most of us have heard of is the Internet protocol know as TCP/IP. The TCP/IP model only uses four of the layers to more simplify the architecture making it streamlined and easier for most to understand. Here are both models and a brief description and example of each.

OSI Model (7 layer)

1. Physical – The electrical and physical connections for devices (example: wires, electrical signals, hubs, network cards)
2. Data Link – Functional means of transferring data between network devices via switches and protocols (example: Ethernet, Token-Ring and switches)
3. Network – This layer is responsible for transferring data between multiple networks via routing protocols (example: Internet Protocol (or IP), ARP, and RIP)
4. Transport – this layer provides a reliable transparent transfer control of data between hosts (example: TCP and UDP)
5. Session – This layer controls the connections between hosts. Establishes, maintains, and terminates connections between hosts. (example: NetBIOS and DNS)
6. Presentation – This is the layer the data is transformed and formatted to provide a standard interface for the Application layer (example: ASCII to XML conversion)
7. Application – Provides services and data to user defined applications (example: RPC, FTP, HTTP)

 
TCP/IP Model (4 layer)

1. Network Access – This is the physical layer like cables, hubs, switches, and routers necessary for communications
2. Internetworking – This is the IP address and layer that allows hosts to be able to find one another on the Internet
3. Transport – Connection protocols like TCP and UDP operate here. This layer deal with the opening, maintaining, and closing connections between hosts
4. Process/Application – High level protocols like HTTP, FTP, SMTP, POP3 operate

Back in the day when I got started in the networking field for a small ISP in Dallas, I had to study the OSI model for Cisco exams. I had to use anagrams to remember the different layers such as (P-D-N-T-S-P-A) “Please Do Not Throw Sausage Pizza Away” or in reverse (A-P-S-T-N-D-P) “All People Seem To Need Domino’s Pizza” so I could keep them all straight. Once I was actually starting to get my hands wet in the field, I found the OSI model to come in handy when trying to troubleshoot networking issues. I had to morph the definitions of the layers to fit my needs, and used them as a daily reference on how to isolate issues and come to a resolution by stepping up and down the layers. Here is what I used to simplify my life when troubleshooting a dial-up connection (analog, ISDN and sometimes a T1).
 

Network Troubleshooting (7 layer/step)

1. Physical layer – Is there good working cable between point A and point B? (the router and switch let’s say). Have you tested the cable to make sure it works?
2. Data link layer – Is there a link light on the router or switch? Is it plugged into the correct ports on both ends? Are the port speeds and duplex settings on either end matched up? (10/full, 100/full or 1000/full)
3. Network layer – Can I ping across the link from the router to the switch? Am I using the correct IP address information?
4. Transport – Am I able to get out of the local network? Is there a firewall that might be blocking something? Is the default gateway setup correctly?
5. Session – Am I able to reach (ping) the end host I are trying to reach? (the web server in this case)
6. Presentation – Is the service I am trying to reach installed and running? (like IIS or Apache) Is there a firewall blocking inbound requests? (hardware or software)
7. Application – Is there actually content on the server to present? (HTML pages) Does the web server config have the appropriate permissions applied and pointed to the correct directory for content?

I know this might seem a little simplistic, but sometimes getting back to the basics is the best way to solve problems. It is also an effective way to teach people interested in networking how to troubleshoot issues that come up in our industry on a daily basis. I hope you find this approach useful and apply it in your environment.


A funny little known factoid is that when we started this company a couple years ago, the OSI model actually came up when designing our logo. When brainstorming and jotting down ideas one of our founders (guess who?) used the 7 Layer theme to design our current logo. Shows you how influential the OSI model has been in today’s Internet driven world.

Let’s see what anagrams you can come up with for “P-D-N-T-S-P-A” or “A-P-S-T-N-D-P” Give me your best shot. (keep it clean though!)