NTP Broadcast Issue

 Many of my regular customers refer to me as the ‘Network Janitor’ because I seem to gravitate to ‘cleaning up’ networks.

In some cases, yes physically cleaning up and organizing datacenters, wiring closets, etc – kind a network version of a personal organizer. In most cases though I clean up the network from the packet perspective.

For years I have been preaching concepts such as ‘The pc bootup and login baseline’ as well as “The VLAN or subnet broadcast analysis”. In both cases, I look for unnecessary traffic to make things run smoother and more efficiently.

In my throughput class I explain how quickly things get messy using basic math. For example, assume you have a 7% broadcast rate on switch where everybody has a 1 Gbps connection.

Then on this same switch assume there is a Wireless access point with a 100 Mbps connection. Here comes the math: 7% of 1 Gbps is 70 Mbps hitting the access point with a 802.11g or 54 Mbps radios. See what I mean.

This is precisely why I look for ways to minimize the number of broadcasts floating around your network.

In this specific example a HP printer was using its default NTP configuration where it transmits a broadcast packet looking for its time server or services. Since this is a large flat network, hundreds of devices ARP for the printer. This wouldn’t be an issue if there were fewer devices within this VLAN, but like I just said, hundreds of devices respond with an ARP broadcast.

Depending when the device’s arp tables expired, I observer anywhere from approx 50 – 7,000 broadcasts per second. After seeing this the symptoms made perfect sense. When there a lot of ARP’s the wireless users got kicked off as well as general performance issues everywhere.

When there where less, then there was just performance issues and general network slowdowns.

Yikkes!! Fortunately in this case just the one printer was configured this way and was easy modified. Regardless, I showed the customer how their current network design is affected by broadcasts

Note the space bar trick doesn’t work anymore.

Documenting Why “Its Slow”

 I can’t tell you how many times I have heard that dreaded phrase, “Its Slow”.

I’ve heard this so many times I typically casually respond with, “Great, what is it and how slow is slow?”

The biggest issue I have with this statement is that this is the typical network complaint that sucks you into the troubleshooting vortex since nothing is clearly defined.

For example, if I said, “email is slow or it takes 2 hours to download my files” you have a chance to address this since I can measure the problem and the end result. The 2 hour comment actually gives you a measurable value to compare against.

One of the toughest things about troubleshooting is when an assumption is made like drive x on the server is fine, therefore the server is fine.

In this example I wanted to demonstrate to a client that one disk or file system on a server can be slower than the other. I also taught him some Wireshark tips and tricks along the way to help him in the future.

Enjoy

One More Thing

 

Everyone loves a good saying. Aphorisms – those terse statements instilled with a modicum of truth – are a popular part of our language. The term originated with Greek physician Hippocrates who once aphorized, “To do nothing is sometimes a good remedy.” Ironically, he is also regarded as the Father of Medicine. The more aphorisms are used, the more credibility they accrue.

It is widely known that actions speak louder than words, he who hesitates is lost, and if you lie down with dogs, you wake up with fleas. It is reassuring that a barking dog never bites, and that absence makes the heart grow fonder.

Our careers are guided by the belief that all that glitters is not gold, that genius is one percent inspiration and 99 percent perspiration, and that all things come to those who wait.

In business as in life, if you do what you’ve always done, you’ll get what you’ve always gotten.

There is one pithy bit of wisdom that has always perplexed me - “If you want something done, give it to a busy person.” I suppose the implication is that busy people are also marvelously capable people who will tackle whatever comes their way. These mythical superhumans may be juggling 10 things but can always handle 11. If they are busy, they must be good at being busy, and have no problem with being busier. I am not convinced.

Many of the busy people I know tend to prioritize haphazardly, playing a virtual game of “Whack-a-Mole” with their lives. This frantic approach leaves self-care – therapy, vacations, happy hour with friends – at the wayside. Adding more moles will only hasten the inevitable burnout.

Once work-life balance became a thing, music, meditation, alcohol, and other distractions gained favor as a way to block out all thoughts of work during “life” breaks. While such redirection may sound healthy and efficient, it can squelch the power of the unconscious mind, which often is a wonderful source of creative thinking and problem solving. For me, solutions to problems often magically appear during these block out periods. The more overwhelmed I feel, the more likely I am to miss out on the hidden power of my drifting mind.

There is an undeniable tendency in our society to admire busy, presumably productive people. These are the folks who got promoted and ascended to the C-suite in all the various businesses I have worked for. This sets the bar high for the rest of us, and I can’t help but become a bit self-critical when I start to feel overwhelmed. Other people can handle this, so why can’t I? I have only one message for the person whose focus becomes even more acute when given that 11th task – I will never be like you.

When I am overcome with tasks, my personal coping strategy is quite simple – I either flail about wildly and inefficiently or I curl up in the fetal position on the floor. My bandwidth for cognition and emotional wellness is destroyed. Striving for thoughtfulness, resourcefulness and self-reliance is cast aside and I begin to overthink, try to do everything myself, and become overly picky about pointless details. Stopping to pet the dog or smell the roses is a bothersome distraction, and I miss opportunities to replenish my emotional reserves.

Perhaps there actually are members of the human race who, unlike me, do not get overwhelmed by taking on just one more thing. All I can say is...

If it sounds too good to be true, it probably is.

Author Profile - Paul W. Smith - leader, educator, technologist, writer - has a lifelong interest in the countless ways that technology changes the course of our journey through life. In addition to being a regular contributor to NetworkDataPedia, he maintains the website Technology for the Journey and occasionally writes for Blogcritics. Paul has over 40 years of experience in research and advanced development for companies ranging from small startups to industry leaders. His other passion is teaching - he is a former Adjunct Professor of Mechanical Engineering at the Colorado School of Mines. Paul holds a doctorate in Applied Mechanics from the California Institute of Technology, as well as Bachelor’s and Master’s Degrees in Mechanical Engineering from the University of California, Santa Barbara.