Re: SV: RE: Hardware shaping

["Ilija Hadzic" <ihadzic@ee.upenn.edu>]

> The problem is that the switch throws away almost all packets from my 
> NIC when they use shaping.  The ISP switch is set to 2.5Mbps shaping. 
> 

This happens because your ISP's switch sees you host as the misbehaving 
source. The traffic contract you have is 2.5Mb/s PCR. Everything above 
that is dropped, because the switch is enforcing this policy which is 
violated by your card. 

To prevent your machine from misbehaving you need the card that supports 
the traffic shaping at the host as I said in my previous reply.

> If the ISP switch is set to 90 Mbps and my NIC to 166 cps (=2Mbps) 
> shaping, it works ok. But, my ISP is not happy about that (90Mbps), 
> because they have heavy traffic at the moment  :-( 
> 

Most likely your computer is the bottleneck in this case and is able to 
fill up only 90MB/s pipe. Therefore it never violates this traffic 
contract and the switch doesn't drop the cells.

> How do I set the QoS parameters to work witch their switch? Are the 
> switch using the same shaping as the NIC? 
> 

Your host must conform to the traffic contract set on the switch. Then 
the switch won't consider it misbehaving and won't drop cells. The cell 
rate is usually enforced at the switch using the leaky bucket algorithm. 
Get any book on ATM to learn how the leaky bucket works. When you specify 
your traffic contract (i.e. 2.5Mb/s), the switch calculates the 
parameters of the leaky bucket and sets one up at the port that connects 
to your host.

I.