[c-nsp] atm ubr settings?

[Roy]

goemon at anime.net wrote:
> I am arguing with another engineer over provisioning of our customer ATM 
> PVCs.
>
> His argument goes something like:
>
> "Configuring every ubr pvc to 45mbps by default does not hurt anything, 
> regardless if the customer's circuit is telco provisioned for 256k or
> 1.544mbps or anything else. Therefore, this is a valuable method to 
> prevent us from having to waste any time ever configuring customer pvcs 
> at all"
>
> He justifies his position with some tcp download tests of the pvc set for 
> the proper (telco provisioned) line rate, and then comparing it to tcp 
> download tests with the pvc set to ubr 45mbps, and seeing "no difference".
>
> I suspect this is a bad idea, but I would like an ATM expert's input on this.
>
> -Dan
> _______________________________________________
>   
It may be a bad idea.  The UBR setting should not exceed the speed of 
the lowest physical link in the PVC.  In my case, we have a 44 Mbps ATM 
pipe feeding many DSL customers.    Too high a setting for the UBR 
results in cell drop at the DSLAM and really lousy performance.