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1. What are the default queue/buffer settings when mls qos is NOT enabled on the switch.
I believe 4x, as all the resource are devoted to a single queue rather than QoS enabled 4 queues.
2. Is there any good documentation out there regarding the buffer sizes of the different switch models
I don't recall seeing good documenation for that.
The customer is looking for an answer as to whether or not replacing the 2960S with a higher model would eliminate the output drops WITHOUT having to mess with QOS/buffer/drop threshold settings on the switch, and Cisco doesn't seem to make the buffer sizes readily available for the the smaller Catalyst switches.
It may, but you might have to jump to a much higher model, e.g. 4500, 4900 or 6500. The 3560 and 3750, I believe, are not that different from 2960s (at least in this aspect). MetroEthernet series switches might have increased buffering.
If you don't have a need for QoS feature, just disabling QoS might provide the resources needed. If QoS is needed, considering the price for a "better" device, tuning of QoS parameters could be considered.
