Question : QOS for LAN Voip

On my network we have a Cisco 1841 router, 2 GS478TP Swithces and 1 Linksys SRW2008P switch. There are Linksys 54G WAPS.

We have a trixbox phone system using Polycom IP560 phones. We are using a T-1 trunk so VOIP is only for on lan calls before going out to the POTS network. We are trying to utilize the eyebeam Xlite softphone client. I am experiencing some stutter during the calls and I assume that this is due to not having QOS defined and setup on my LAN.

All of my network enabled devices are on the same subnet with the 10.0.1.x network. We have about 35 users, 35 phones, 7 (networked) printers and 5 servers. I don't know if the subnet is causing the issue.

What sequence of events should I follow to setup QOS (if I NEED to setup QOS at all)

Answer : QOS for LAN Voip

If everything is on the same LAN, then nothing talks to a router. Only a router or a Layer 3 switch performs Layer 3 functions. You cannot have Layer 3 QOS like DSCP without a router to read the DSCP flags in the IP header. All that is there is a switch port on a switch which may or may not support any sort of QOS.

Even if you had a Layer 3 switch which supports DSCP, that function is not controlled on the switch port, it's implemented between the VLANs. So having everyone on one VLAN means DSCP is useless for the reason I just stated.

If you are using soft phones then the PC and the phone must be on the same VLAN. So you need a switch that supports Layer 2 QOS, which is Class of Service (COS) and a couple of other functions. The soft phone marks its traffic as high priority, and the switch ports will prioritize the traffic

The Cisco switches support this. I don't know if yours does.