QOS external but not internal speed?

Probably an easily answered, question, but I've noticed that when I QOS 1 subnet, it also QOS the internal speed.

I have 3 separate subnets.

1 - Eth0 Production Internal
2 - Eth3 QC Internal
3 - Eth4 R&D Internal

So of the 10Mbps Fibre I have, I would like unlimited internal speed but would like external speeds:

Eth0 @ 5Mbps
Eth3 @ 1MBps
Eth4 @ 4Mbps (or whatever is left over)

Ideas?

Thanks!