Even though Microsoft have played the card that network QoS is not a requirement for enterprise voice deployments for OCS I thought I would blog about some QoS settings that can be used in an enterprise environment to help improve MOC QoE. Of course, these settings are not much use if you do not support DSCP on your network. Vista and XP are somewhat different in the ways they support QoS. Vista offers a much more granular form of QoS and allows the administrator to use group policy to set specific rules on an application basis. The following is the registry changes required to enable and alter QoS setting in Vista for MOC:
Windows Registry Editor Version 5.00
"Local Port"="XXXX:XXXXX" (port range removed for security)
"Local IP Prefix Length"="*"
"Remote IP Prefix Length"="*"
As you can see through group policy in Vista we can target not only the application but also the port range. If we were to take it further, you could also specify IP subnets. This level of granularity is important for a number of reasons if your switch ports in your network do not trust QoS settings from PC’s. No one wants someone setting the priority on non-real time applications like email for instance. However, with this type of control on what applications get to set their QoS settings through group policy we could enable QoS to the PC and ensure rogue applications are not consuming valuable bandwidth set aside for real time application like voice.
Unfortunately, XP doesn’t have the same granularity as Vista and the registry settings look something like this:
This allows XP QoS to be enabled but with no strict granular controls other than limiting port ranges.
As mentioned earlier this is all depends on your network QoS supporting DSCP. Vista provides the best QoS configuration and is easily configured through group policy. Working in a hostile network environment which is pretty typical of most enterprise networks choosing to deploy some form of QoS for an OCS pilot if it is already deployed for IP phones is a great idea. Nothing kills a VoIP pilot quicker than poor voice quality and although some environments may exist quite well without it, large environment with WAN links and varying amounts of bandwidth capacity will certainly benefit from QoS even with the Microsoft RT Audio codec’s.