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