Fractional Fast-E and QoS
I have a question regarding Fractional Fast-E and QoS. If you have a router subscribed to say a 20Mb MPLS circuit, it is advisable (even necesary) to use a FE interface for connectivity versus GE interface when you are running VoIP or any delay-sensitive apps. It seems that QoS is not enough to combat the discrepancy between the higher clock-rate that GE sends traffic on the wire in spite of a QoS/Shaping policy applied to the WAN interface. I have run into this situation in the past where VoIP quality was very poor until I switched the WAN interface to FE. My rule of thumb was if you subscribe to 100Mb or less, use FE ports.
If someone can point me to a URL/resource on CCO that explains/confirms this I would be very grateful for your help.
Thanks in advance,