Hello Frank,

if you are using bridging over a WAN link and no L3 device is involved you can try to take advantage of SRR queueing in C3750

>> In shaped mode, the egress queues are guaranteed a percentage of the bandwidth, and they are rate-limited to that amount. Shaped traffic does not use more than the allocated bandwidth even if the link is idle. Shaping provides a more even flow of traffic over time and reduces the peaks and valleys of bursty traffic. With shaping, the absolute value of each weight is used to compute the bandwidth available for the queues.

see

http://www.cisco.com/en/US/partner/docs/switches/lan/catalyst3750/software/release/12.2_46_se/configuration/guide/swqos.html#wp1200681

the shaped mode should be the one that fits your needs.

you need to configure appropriate marking on ingress interfaces

Edit:

with routers you could use hierarchical QoS shaping all traffic to 2 Mbps and invoking a child policy with a scheduler.

with C3750 switches you may be able to find only an approximate solution

Hope to help

Giuseppe