QoS troubleshooting with Wireshark

During my work i have a lot of VoIP traffic related queries/questions. I’m using this configuration to check if packets are being tagged with the right DSCP values.

Add DSCP column to your Wireshark Client

1. Right click on one of the existing columns.
2. Click on column preferences
3. Click Add down the bottom
4. Click on the “New Column” Label and change it to “DSCP” then hit enter once.
5. With the new entry highlighted, change the Field Type to Custom (in the dropdown box)
6. In field name, copy and paste in ip.dsfield.dscp
7. Click Apply/Ok

You can drag the column back to the left side of the Info column and you now have a simple view of the tag for any packet.


You can also set a filter to capture all packets with DSCP value 46

ip.dsfield.dscp == 46


Here’s a table of DSCP and TOS values in their most common formats just for reference.
TOS (Dec) TOS (Hex) TOS Precedence Name TOS Delay flag TOS Throughput flag TOS Reliability flag DSCP (Hex) DSCP (Dec) DSCP/PHB Class
0 0x00 Routine 0 0 0 0x00 0 none
4 0x04 Routine 0 0 1 0x01 1 none
8 0x08 Routine 0 1 0 0x02 2 none
12 0x0C Routine 0 1 1 0x03 3 none
16 0x10 Routine 1 0 0 0x04 4 none
32 0x20 Priority 0 0 0 0x08 8 cs1
40 0x28 Priority 0 1 0 0x0A 10 af11
48 0x30 Priority 1 0 0 0x0C 12 af12
56 0x38 Priority 1 1 0 0x0E 14 af13
64 0x40 Immediate 0 0 0 0x10 16 cs2
72 0x48 Immediate 0 1 0 0x12 18 af21
80 0x50 Immediate 1 0 0 0x14 20 af22
88 0x58 Immediate 1 1 0 0x16 22 af23
96 0x60 Flash 0 0 0 0x18 24 cs3
104 0x68 Flash 0 1 0 0x1A 26 af31
112 0x70 Flash 1 0 0 0x1C 28 af32
120 0x78 Flash 1 1 0 0x1E 30 af33
128 0x80 FlashOverride 0 0 0 0x20 32 cs4
136 0x88 FlashOverride 0 1 0 0x22 34 af41
144 0x90 FlashOverride 1 0 0 0x24 36 af42
152 0x98 FlashOverride 1 1 0 0x26 38 af43
160 0xA0 Critical 0 0 0 0x28 40 cs5
176 0xB0 Critical 1 0 0 0x2C 44 voice-admit
184 0xB8 Critical 1 1 0 0x2E 46 ef
192 0xC0 InterNetworkControl 0 0 0 0x30 48 cs6
224 0xE0 NetworkControl 0 0 0 0x38 56 cs7

Polycom Trio 8800 failed to discover exchange server (Office365)

Polycom Realpresence Trio

Deployed some Polycom Trio’s in my organisation (we’re running Exchange Online and Skype for Business Online) and everytime i went to the Calendar the Polycom was showing an error “Failed to discover exchange server”.

How to solve this error

Login to the webinterface from the Polycom Trio 8800 (first time enable HTTP/HTTPS connection from the Polycom Advanced Option, Default password is “456”)

Go to Settings > Applications

Disable the AutoDiscover and Fill in the following Exchange Server url:


Save configuration and restart your Polycom device.

No presence information in Outlook (Skype for Business)

Got an issue after installing the Mitel MiCollab software. Microsoft Outlook did not display the status of Lync/Skype anymore. Also in my Outlook client the information from GAL (Global Address List) was not visable anymore when hovering over a name.

Some other issues i found out:

  • The Microsoft SharePoint client/web does not display presence information.
  • Other Microsoft Office applications that support presence features do not display presence information

The Solution

This behavior may occur if the value of the DefaultIMApp registry entry in the following registry key is incorrect:

First, look at this location in the registry…

[HKEY_CURRENT_USER\Software\IM Providers] 

It should show this value:


If there is any other value, change it back to “Lync”, in this case the MiCollab software is changing this value to “Micollab”.

Now restart Outlook and see if your presence indicators are back.

Note: The DefaultIMApp registry entry specifies which IM application provides IM and presence information in Office applications.

.NET Framework 4.6.2 is supported with the February 2017 Cumulative Update for Skype for Business Server 2015

Both Lync Server 2013 and Skype for Business Server 2015 are supported with the .Net Framework 4.6.2.

Skype for Business Server must have the February 2017 update for Skype for Business Server or later installed.

This update can be found at https://support.microsoft.com/en-us/help/3061064/updates-for-skype-for-business-server-2015

Lync Server 2013 must have the November 2016 update, or later installed. This update can be found at https://www.microsoft.com/en-us/download/details.aspx?id=36820.

How to configure IIS ARR for Skype for Business


Open your IIS Manager, right click “Server Farms” and “Create Server Farm”.


Specify a Server Farm name, i used Skypeweb


Click “Next”.

Server address must be your Front-end pool, click show advanced setting and set the following ports
httpPort 8080
httpsPort 4443
And click “Add” and “Finish”
These ports are configured on your Front-end server for external traffic.
Click Yes at the next screen. (this will save you some time later..)


Now select your Skypeweb from the server farms.

We need to configure this farm with some specific settings.
Double click “Caching”

Turn off Disk cache, and click “Apply” on the right side of the screen.

Go back to your server farm and select “Proxy”

Set “Time-out(seconds)” to 600 and click “Apply”
This will prevent mobile users from disconnecting.

Now go back to your server farm and select Routing Rules

Disable SSL offloading by unchecking the Enable SSL offloading box and click Apply.
Now click on the right side “URL Rewrite”

You will see 2 rules.

Delete the NON SSL one.

Double click the SSL one

Now change “Using” to “Regular Expressions”
And change the “Pattern” to “(.*)

Under conditions make sure HTTPS is “On”

Now Click “Add”

Create the condition Inport {HTTP_HOST}
Select matches the Pattern
Pattern: skypeweb.skypedev.nl|meet.skypedev.nl|dialin.skypedev.nl

This are all the subdomain you will need for Skype Web Services.
Make sure below action is everything configured right (should be done automatically)

Don’t forget to “Apply”