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We have about 200 IP phones in our building and I realize we got more complaint about the phone quality after we switched our internet from 50Mbps to 200Mbps Up/Down.

I know there's a possibility that the switch gets overloaded easier than before cause obviously everyone is using more bandwidth. And most of our switches are still 100Base-T.

So is there a way I can monitoring the load on the switch or get a notice if the switches gets overloaded?

We're using Dell PowerConnect 3548 mostly.

Thanks.

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Most likely, it's the links between the switches that are getting overloaded. Trunking two 100Mbps lines for inter-switch links and reducing your network diameter (by, for example, connecting all switches to a single "core" switch) may help. –  David Schwartz Jan 18 '13 at 23:59
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"cause obviously everyone is using more bandwidth" - Why would everyone obviously be using more bandwidth? Because you upgraded your internet connection your users automatically start consuming more bandwidth? That's an assumption I wouldn't make. –  joeqwerty Jan 19 '13 at 0:57
    
@joeqwerty: A better way to put it is this: Previously, Internet traffic was low enough in volume that it couldn't saturate switch to switch links. Now it can. (And this means that part of the solution is to realize that it's very important where in the switching network the internet connection is. For example, if it's "on an end" there will be more switch-to-switch traffic.) –  David Schwartz Jan 19 '13 at 1:09
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1 Answer

up vote 3 down vote accepted

You can monitor the statistics of every single port on the switch using SNMP. This will give you your individual throughput on each port, tally them all up at any given time and that gives you your total traffic.

If that traffic is higher than your switches backplane, then your switch is the bottleneck.

You should also monitor your uplink ports. If they are saturated, then they are the problem and you need faster or more uplinks.

If neither, then it's something else. If your computers are piggybacking off a built-in switch on the phones, then perhaps the computers are saturating the switch in the phones. You should also be able to monitor these via SNMP as well.

Ideally you should have your phones and your computers on seperate vlans. Then you can put QoS on your outbound internet connection to give priority to the phone vlans to ensure that theres always enough outbound bandwidth to satisfy the phone calls.

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An inexpensive way to do what Mark Henderson suggests is with a tool like CactiEZ. –  JasonAzze Jan 19 '13 at 15:41
    
Thanks Mark, very helpful! –  Carl Jan 20 '13 at 20:21
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