On Tue, 18 Apr 2000, Kevin Oberman wrote:
Alex,
your description of how the MAE ATM NAPs work is not quite in line with either my understanding or the ATMF traffic management specs.
I'm not surprised, as I may not know what I am talking about :)
As you state, the connections to the NAPS is ABR, but you then say "with PCR being twice SCR". If the connection is ABR (and it is), there is not PCR or SCR. There is only MCR (minimum cell rate). This really means that you are guaranteed that the bandwidth reserved by the MCR will be available to you. Any traffic beyond this is treated on a best-effort basis, exactly as if it was UBR. The only limit on what you may inject (above MCR) is the line rate and there is no guarantee that any of this traffic will make it through the fabric.
I thought it was strange also, however my information comes from Wcom: <snip>
3) is it still VBR, or UBR/ABR now?
It's actually implemented as ABR, with the peak cell rate enforced and set to twice the reserved rate. </snip>