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New Member

Test IP phone with, and without QoS

  Hi all!

  I would like to try this:

1 - Connect an IP phone in a switch (without QoS) and generate a lot of traffic in the trunk to force the voice to interruptions.

2 - Connect an IP phone in a switch (with QoS) and with the same traffic verify that the QoS works fine.

But the step 1 failed. Not cut of voice, only a little bit of delay. I generate traffic with ping in 4 switch and SolarWinds WAN killer.

ping repeat 2100000000 size 18024
( is the IPphone into the switch)

I check the traffic in the trunk with Cacti (see attachment).


¿What i doing wrong?


Everyone's tags (1)

What's the full topology for

What's the full topology for the phone call?  Just 2 IP Phones on the same switch calling each other?

New Member

   Hi Brian, see these


  Hi Brian, see these attachment.

 SW4, SW1, SW2 with QoS configured.

 SW3, SW5 with out QoS

Both phone on the same vlan.

Thanks for reply


So for audio quality between

So for audio quality between the phones, we only have to worry about the switches since both phones are on the same VLAN.  What model switches are these?


The switches by default should have different input/output queues it places things into based on DSCP/CoS.  This could be resulting in the default settings being okay enough.  Can you set WAN killer to tag the packets with a DSCP value of 46(EF)?  That may help in exhausting the queues being used for the voice traffic and causing the packet loss you're trying to show.

New Member

   Hi again, the model of


  Hi again, the model of switch:

SW3 and SW5 are WS-C2960-24TT-L    12.2(55)SE8  

SW4, SW1, SW2 are WS-C2960G-24TC-L    12.2(55)SE8 

I can't set WAN Killer for tagging packets. I don't know what to do.




Try using something like D

Try using something like D-ITG as referenced here-


It should do the same as WAN Killer and allow you to set DSCP.

New Member

   I already saw these link: 


  I already saw these link:

  But i can´t get work D-ITG, i'll try again.

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