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Re: M4300/S3300 VoIP Traffic Loss


M4300/S3300 VoIP Traffic Loss



we heave some critical problems with our new Netgear Switches with QoS. Our network is designed as "spine-leaf". We have two stacked M4300 as Core- and 20 S3300 as Access-Switches. Some Access-Switches are stacked too and are connected to the core via 10 GBit/s fibre. Each Access Switch or Access Switch Stack is connected to each core with one fibre cable - so we have redundancy. The Uplinks are configured as LAG with LACP on each Core-(Stack) and Access-(Stack) Switches. Network is generally working - we have no performance problems, everything is working fine, but most voice calls are instable, e. g. words are missing. Our VoIP-Gateway (ALCATEL) fills the ToS Value with DSCP EF (46), so based on Layer 3 QoS. First we used NetGear AutoVoIP and configured it as shown in the manuals and by help of L2 Support, but that didn´t work for us. On all Switches under AutoVoIP status we could see that no voice channels were detected, so I think AutoVoIP did not work. We also configured a separate VLAN and activated VoiceVLAN but that also did not work for us.


Now I tested the QoS Menu under all Switches (M4300 + S3300). First I had set the global 802.1p standard to DSCP an changed EF to Queue 4(on cisco switches thats all and QoS works fine for voice traffic). On our Netgear Switches still have the same problems with missing words or ending calls.


So I used WireShark to check the voice traffic and here are some Screenshots. I can see that some packets are marked as wrong sequence number (this could may be a problem of wireshark), but the delta time (ms) is too high, so thats why words are missing in some voice calls.


After that I tested some new settings in the QoS menu --> DiffServ (I had set the DSCP standard unter the menu QoS --> CoS). There I crated a new class with our voice VLAN ID binded to it. After that I created a new policy, which forwards this traffic to Queue 4. These settings are shown in some NetGear manuals, but it seems that also this is not working for us. I had set this on all switches (Core and Access) with policy type IN.


We escalated our ticket to L3 Support, but we are waiting for some response. So can anyone help us, what we can test furthermore? Where can I monitor if Netgear puts voice traffic to the right queue? I have no more ideas...

So is it may a problem with the VoIP Gateway or the VoIP phones? What can I test to identify the problem?









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Re: M4300/S3300 VoIP Traffic Loss

Hi MasterPhil,


Welcome to Netgear Community!


We need more detailed info as below for debugging this problem, could you 

1. Which protocol is used by your VoIP phone? SIP, H.323 or other? 

2. What brand of your VoIP phone? Does the 'Telephony OUI' is in Netgear Switch 'OUI Table' list?


As you know, Auto-VoIP support protocol-based and OUI-based mode. In both two mode voice traffic can be set to high queue and transmit by high priority, but only in protocol-based mode, the voice session can be counted to Voice Channels. 


So In your case, do you enable both protocol-based and OUI-based mode on 'Auto-VoIP' configuration page? And you can try these two mode in your side and check whether voice words are missing or not?


For Auto-VoIP configuration, please refer to below link(page128: Auto-VoIP Configuration):




Hope it helps!




Netgear Employee

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