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The Art of Network & Application Performance Analysis™
The Myth Series: “The Myth of Network Utilization”
Why art and not science? It is science—but a science of approximation. Application of the science--is an art. The tools involved all act like they are sure--but they are estimating. The trick is for the Network and Application Performance Analyst do things in a manner where the estimates are meaningful and produce actionable results. Not being fooled.
Take the two leading Packet Analyzers—Sniffer and Wireshark. The following are the simple statistics for the same trace file as reported by both products:
Wireshark:
File size: 719,358
Data Size: 684,950
Average Packet Size: 799
Sniffer:
File size: No Value Provided--But Windows shows: 703 KB
Total Bytes: 688,378
Average Packet Size: 803
These are all very fundamental values--yet they don’t easily reconcile. Once you get to more abstract values—thing get tricky.
UTILIZATION: What does it mean when a tool tells you that your network/segment/WAN is 42% utilized?
- Does it mean that the wire is only used 42%? No.
- If you are measuring a transport medium, that medium is utilized 100%--whenever it is used. If you put an electrical current on a wire—can you use only 42% of that wire? No. It is either hot or cold. On or off.
- Does it mean that you only used it 42% of the time? No.
- It is getting closer though. To say that it means that the segment is 100% utilized—but only 42% of the time—is almost correct.
- Time is the key word here. How is it measuring time?
- Is it always monitoring or is it polling? It is polling--probably.
What is your polling interval? Every 10 minutes—every hour—once per day?
How long to you monitor between polls? Is it a “continuous” value only checked on every hour? Is it an interval that the manufacturer has never even disclosed or acknowledged?
For the sake of discussion--let’s answer these questions. Imagine we have a tool that monitors a wire for 1 minute every hour. That tool reports that your “Utilization” is 42%.
That means that for the one minute every hour--that your wire is monitored. For that one minute only-- it is 100% utilized. In other words--42% of those polls showed 100% (rather than 0%) utilization—for 1 minute per hour.
Does that mean that it has 58% more room and all is well? No.
So, what do you know about the utilization of your wire that can help you? Not as much as the monitoring tool’s manufacturer would like you to think. Are you attempting to reconcile the results of two different tools? That is extremely difficult--impractical--and possibly ruinous.
How much money are you spending—not only on the tool itself—but on decisions made as a result of that tool’s reports?
The Good News:
This doesn’t mean that there is no point to those metrics. Nevertheless, you should certainly not quote them when reality seems to imply different things. Reality is going to be more accurate that such metrics—every time.
Interpath Technologies has developed real life methods of analyzing how networks and applications truly perform. It is not a “black box” approach and requires a human being to work with the metrics. We run live user tests using various protocol analysis tools like Wireshark and Sniffer. But we do not listen to them slavishly. We have a proprietary methodology that has provided realistic perspectives to the art of Network Application Performance Analysis and Troubleshooting--for the past 11 years.
We cut through opinions--diagnose facts--provide resolution.
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