| The Interpath Technologies Networking Myths | | | | your metrics are already mostly useless |
| Series (TM) | | | | (unless you have equal activity at night as |
| | | | during the day). |
| This artilce is also availabe as a Podcast of | | | | |
| "The Sniffer Guy" though iTunes. | | | | If it is hourly--and day time only hours--it |
| | | | still means that 4 out of 24 business hour |
| Mythology is not fantasy or lies. It | | | | polls are 90 seconds. That does NOT mean 4 |
| describes a basic truth-but as metaphor. If | | | | times--it means 4 times "POLLED." What about |
| you understand that it is describing a | | | | in-between polls? It is happening many more |
| fundamental reality-by telling a story-you | | | | times than the 4--that were able to be seen! |
| know to look for the reality behind the | | | | |
| story. If you believe the story-you will | | | | It could be happening more than enough to |
| chase your tail until you decide to ignore | | | | significantly damage production and good |
| everything. So, when I say that automated | | | | will. |
| testing and metrics like utilization are | | | | |
| myths, I mean that they are metaphors-stories | | | | Is the logic in your automated tool really |
| that can direct you to the truth. They are | | | | taking this into account? If so, what does it |
| not the truth in themselves. | | | | really tell you anyway? It can't say why--and |
| | | | it can't say how. It's a fire alarm that only |
| What is the IT person's mission? The mission | | | | rings if you pull it at the right time and |
| is to keep a set of instructions (apps) | | | | frequently enough. |
| interfacing with humans (users), over an | | | | |
| enormously complex environment (enterprise | | | | That discussion opens the door to wondering |
| networks and the Internet itself). Many | | | | about metrics in general. |
| senior and seasoned IT professionals have | | | | |
| developed a sense over the years that | | | | UTILIZATION METRICS: |
| something isn't quite right. There is too | | | | |
| much "hoping" going on and not enough | | | | What does it mean when a tool tells you that |
| "knowing." | | | | your network/segment/WAN is 42% utilized? |
| | | | Does it mean that the wire is only used 42%? |
| An IT support person is attempting to | | | | No. |
| visualize the transport of discrete units of | | | | |
| data flowing across an "Interpath" between | | | | If you are measuring a transport medium, that |
| all the applicable components--for hundreds | | | | medium is utilized 100%--whenever it is used. |
| of applications and thousands of users. How | | | | If you put an electrical current on a |
| is that done? Black magic mostly--and a bag | | | | wire-can you use only 42% of that wire? No. |
| of black box tools. | | | | It is either hot or cold. On or off. |
| | | | |
| Often these tools are purchased by less | | | | Does it mean that you only used it 42% of the |
| technical management and the support | | | | time? No. |
| personnel receive little training. Even if | | | | |
| they do receive training, that training is | | | | It is getting closer though. To say that it |
| focused on how to manipulate the console and | | | | means that the segment is 100% utilized-but |
| install the product. Seldom is there much raw | | | | only 42% of the time-is ALMOST correct. Time |
| technology exchanged. Let's face it, most of | | | | is the key word here. How is it measuring |
| the time we don't really know what the tool | | | | time? Is it always monitoring or is it |
| is doing--only how to run it--yet we take | | | | polling? It is polling--probably. |
| their results as law. | | | | |
| | | | (Sorry--polling and metrics are always |
| Tools poll and push and query and ask a | | | | hand-in-hand). |
| selection of the components involved to | | | | |
| report in about themselves. Then, by | | | | What is your polling interval? Every 10 |
| algorithms known to only a few people at the | | | | minutes-every hour-once per day? How long do |
| vendor's office, (if they are still employed | | | | you monitor between polls? Is it a |
| there), the data is SUMMARIZED and presented | | | | "continuous" value or is it only checked on |
| to you, the IT professional who has received | | | | every hour? Is it an interval that the |
| that week of training. | | | | manufacturer has never even disclosed or |
| | | | acknowledged? |
| Once you think about the fact that the | | | | |
| information is just a summarization--the | | | | For the sake of discussion--let's answer |
| problem--and mythology--begins to come clear. | | | | these questions. |
| | | | |
| AUTOMATED TESTING: | | | | Imagine we have a tool that monitors a wire |
| | | | for 1 minute every hour. That tool reports |
| Picture a business user sitting at a PC | | | | that your "Utilization" is 42%. |
| workstation in a remote office of your | | | | |
| company. Many times a day--a network | | | | That means that for the one minute every |
| transaction that should take 15 | | | | hour--that your wire is monitored--for that |
| seconds--instead takes 90 seconds--maybe | | | | one minute ONLY-- it is 100% utilized. In |
| longer. | | | | other words--42% of those polls showed 100% |
| | | | (rather than 0%) utilization-for 1 minute per |
| You have an automated tool that "simulates" | | | | hour. |
| that transaction every hour. In 24 polls we | | | | |
| see the following: | | | | Does that mean that it has 58% more room and |
| | | | all is well? No. |
| * 4 Samples show 10 seconds (much faster than | | | | |
| normal) | | | | So, what do you know about the utilization of |
| | | | your wire that can help you? Not as much as |
| * 16 Samples show 15 seconds (expected) | | | | the monitoring tool's manufacturer would like |
| | | | you to think. |
| * 4 Samples show 90 seconds (long enough to | | | | |
| drive a user crazy.) | | | | Are you attempting to reconcile the results |
| | | | of two different tools? That is extremely |
| * The average is 26.7 seconds. | | | | difficult--impractical--and possibly ruinous. |
| | | | |
| Would an alarm sound in your monitoring | | | | How much money are you spending-not only on |
| system? With an expectation of 15 | | | | the tool itself-but on decisions made as a |
| seconds--would you be concerned enough to | | | | result of that tool's reports? However, this |
| escalate this issue? Sure, it's nearly double | | | | doesn't mean that there is no point to those |
| what is expected--but there are times that | | | | metrics. They are signpost pointing towards |
| are quite excellent and anyway--it's still | | | | reality--fire alarms. Nevertheless, you |
| not even 30 seconds! Maybe it's not so | | | | should certainly not quote them when reality |
| critical... | | | | seems to imply different things. Reality is |
| | | | going to be more accurate that such |
| It is Critical--to that user experiencing 90 | | | | metrics-every time. |
| second delays from time to time--or more | | | | |
| frequently! | | | | This is the reason for the Interpath |
| | | | Transactional Analysis approach to monitoring |
| What is your Polling Interval? Hourly? -- | | | | and reality based testing. |
| Does that include night-time hours? If so, | | | | |