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One of my small IT customers hired a consultant to save them money. They use voip and have video surveillance cameras the owner watches remotely. They also have about 10 people in the office at any given time and offer free wifi to customers.

I set the network up and have a basic router with qos enabled for the voip traffic. We were having upstream issues and the provider stated that we were probably hitting our upload limit of 2mb and that was causing the voip drops. I increased it to 50/5 and the problem has went away. Now the consultant has presented me with this graph that I've never seen. The speed increase happened on 4/14. There is a drop in the numbers at that time.

My arugment is that, this graph only shows averages, not peaks. And the peak upstream usage is when we are having the problems.

Do you see anything different or am I interpreting this graph incorrectly?

Analysis image[1]

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  • To correctly configure QoS for VoIP, you should have a priority queue, which dedicates a portion of the bandwidth for VoIP. Hitting your maximum bandwidth wouldn't affect the VoIP since it uses a priority queue. One problem is that you have no real control over incoming bandwidth, and that is usually what hits the wall. By the time you see, and can control, incoming traffic, it has already used your bandwidth.
    – Ron Maupin
    May 9, 2016 at 17:36
  • Everytime we've had a voip issue, theyve not been able to hear us but we can hear them. Which indicates to me its an upstream issue.
    – ahackney
    May 9, 2016 at 19:51
  • You still need to have a priority queue, dedicating a portion of your bandwidth to VoIP. If you have that, it may not be large enough for your VoIP traffic. You shouldn't need to increase the bandwidth unless the size of the priority queue doesn't allow enough other traffic. Another problem could be that you are not separating the VoIP and other traffic on your LAN (separate VLANs for VoIP). You should mark the VoIP traffic as close to the source as possible. Many switches will reset QoS back to BE unless you specifically trust or mark on the switches.
    – Ron Maupin
    May 9, 2016 at 19:55
  • This is a small network. We have one router and one switch. We are working with 2mb up stream, which is fine for voip but occasionally we are having network drops that are causing the caller not to be able to hear us. Which indicates to me its an upstream issue.
    – ahackney
    May 10, 2016 at 16:42
  • It could certainly be a problem on your network if you don't separate the VoIP and other traffic, and you really need to use a priority queue for VoIP. You keep saying it is an upstream problem, and it may be, but unless you configure QoS correctly for the site, you can't eliminate site problems, and without a priority queue for VoIP, you are probably creating your own upstream problem.
    – Ron Maupin
    May 10, 2016 at 17:01

1 Answer 1

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Based on the characteristics of the graph provided, this appears to be an MS Excel generated line chart. The question is the nature of the data used to build the chart and how the data was imported. Do you even have assurance that the data represented is accurate? What time zone do the times represent?

Each data point on this chart represents a day and is connected by a line. Without any other frame of reference, there is no way to understand what these data points are representing. Here are some possibilities:

  1. Daily maximum/peak
  2. Daily low
  3. Daily average
  4. Daily median
  5. Another daily measure, such as a 95% value

The other concern is how the data is collected. If collected at five minute intervals (not uncommon), you also may not see high utilization (i.e. one minute with high utilization and four with low utilization won't necessarily look high).

Ultimately, this is all somewhat meaningless as you are trying to solve a specific problem and I don't see how this chart is helpful in that endeavor unless it is providing some sort of relevant, meaningful data. This is something that I don't believe has been established with the information you have provided us.

Keep in mind that your issue with VoIP is just a symptom of the actual problem, not the problem itself. You believe you have found the source of the problem by upgrading your down/up speed, but again without relevant, meaningful data you can't know this for sure. All you know is that the symptom you are aware of seems to have been alleviated. However, this could be somewhat like spraying a numbing antiseptic onto a scrape and saying that because it doesn't hurt anymore the problem (i.e. the scrape) is fixed. The underlying problem is still there, you have simply treated a symptom of that problem.

As Ron has mentioned in the comments, for VoIP you should really be running some proper form of QoS to ensure it has the bandwidth needs it requires. Then, you should start monitoring your network so you can understand what is going on and the data you are getting out of it. This way you will be able to start understanding what is normal and what isn't normal on your network.

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  • What tools are recommended for monitoring? Is there a device that I can plug in to the network to do that monitoring remotely?
    – ahackney
    May 10, 2016 at 16:41

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