I have an issue with voice quality in calls. When yo call the call is established correctly, but after 2 or 3 seconds, the voice quality degrades until it is almost impossible to hear something. The call is never droped.
I'm new in VoIP troubleshooting, soif somebody can guide me trough this problema I have. Also, in the Data network I start to configure QoS. In switches I'm configuring mls qos trust dscp. But in routers this command is not available. Does the routers will forwards packet and keep the EF mark attached to it?
Routers don't need the trust command like switches. You do however have to deploy a QoS model on all of your WAN egress ports to prioritize your voice traffic. It will be overrun by all the other larger TCP packets otherwise.
COS is a layer two designation and DSCP is layer three. You can use a COS to DSCP map in the config.
What do you mean by "assign a COS of 5 in the switch"? The phones already mark (or color) the packets. You just need to use QoS to prioritize the EF marked packets on a per hop basis through your network.
Start with the basics. Be sure you are trusting DSCP on all of the switch ports that carry voice traffic. Then get QoS configured on your routers. Just this much will do wonders for your voice quality.
BTW - What codecs are you using? I typically use G.711 on high speed LAN segments and G.729a on slower WAN links. Have you defined regions on your CallManager cluster?
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The short answer is that you don't.... That isn't entirely true while at
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Topology: IP Phone > Switches > Microsoft NPS setup to forward 802.1x
proxy to > ISE 2.1 patch 3 Authentication: EAP-TLS using Cisco MIC SANs
Phone Models 802.1X support? 802.1x flavor Addtl Comment EAP-MD5 EAP-TLS
Cisco 3905 Y Y N Cisco 6911 Y Y N Cisco ...