Marwan, not sure I understand your comment.
The srr-queue command I think we're discussing, the "srr-queue bandwidth limit" (forgot to add "bandwidth" in prior post), does not allow full utilization of the link.
To quote from Cisco's reference manual:
"Usage Guidelines
If you configure this command to 80 percent, the port is idle 20 percent of the time. The line rate drops to 80 percent of the connected speed. These values are not exact because the hardware adjusts the line rate in increments of six. "
Effectively, as I noted in my prior post, the port behaves like a slower port, because of it being idle some of the time. Or, the effect would be somewhat like using a shaper (which I believe isn't supported on the 3750).
It's also not clear to me exactly what you mean by "while with policing u cam rate limit the traffic at the maximum rate !! "
One advantage of using the policier, it can be much more precise in the bit rate. However, as policers do, traffic above the bit rate will be dropped but traffic delayed by "srr-queue bandwidth limit" should be queued in the port queues.
[edit]
PS:
BTW:
Reading the above, you can see the "six" I remembered, but I now recall there are not six notches but jumps of six. I believe percentages of 1..6, 6...12, 13..18, etc., are treated something like 6%, 12%, 18%, etc.
