Re: Hardware shaping

[Gianluca Insolvibile <g.insolvibile@cpr.it>]

Hi,
as far as I know, the PCA200E performs hardware shaping by inserting "idle" cells in the output cell stream, which is always transmitted at 155 Mbps (i.e., if you want to transmit cells at 100 Mbps, the NIC will alternate sending 2 "normal" data cells and 1
idle cell, with a constant rate of 155 Mbps).
If I'm not wrong, the idle/good cells ratio is controlled by the driver, which has no other means to lower to transmit rate.

Regards,
    Gianluca

Ronnie Lindgren wrote:

> Hi all,
>
> Question:
> Exactly, how does the hardware shaping work on the PCA200E with Linux ATM?
>
> Our config:
> atmarp -s 195.163.xx.yy  0.0.33 qos cbr:pcr=166cps
>
> Problem:
> In this case, our ISP's ATM-switch cuts our traffic when it is heavy loaded. Small packages can get through (5 bytes). Big packages don't.
>
> It seems that the Linux-ATM shaping is different than the switch (unknown brand). When our ISP configures their switch to 80-90 Mbits/s everything works ok. But, when shaping is set to 2.5Mbit/s on the switch (same as our shaping above?) it don't work. Why?
>
> /Ronnie
>
> kernel - linux-2.0.29
> atm    - atm-0.31
> pca_200e - pca_200e-0.2
>
> ____________________________________________
> ronnie@radiolan.se
> ____________________________________________



--
+------------------------------------------------------------+
| Gianluca Insolvibile                                       |
|                                                            |
| Consorzio Pisa Ricerche       email: g.insolvibile@cpr.it  |
| Gruppo META                                                |
| Corso Italia, 116             Phone: + 39 050 915825       |
| 56127 PISA (Italy)            Fax  : + 39 050 915823       |
+------------------------------------------------------------+