I was forced to use a 3750G as a router yesterday for a WAN link that was only 70Mb. The LAN interfaces were all gig. The customer wanted to ensure that 30% of the bandwidth was available for EF marked packets. Everything else was to get 70% A lot of people have trouble with QoS on the 3750. This is mainly due to the tiny buffers, complexity, and the defaults it uses. Let’s use the following network for this post: The laptop on the left is connected on a gig port running iperf on linux. The laptop on the right is connected to a hard-coded 100Mb port.