Luca, I am using this in a fully controlled environment in which all nodes (including switches and machines) have both flow-control on for tx and rx. Now my question is just about the pf-ring aware drivers, do they support flow control? because using normal drivers, even packets are not dropped along the network they might be dropped in the pf_ring kernel module. However, I assume pfring_driver will copy packets directly to the kernel module buffer and skips kernel buffers(backlog). Does it mean those drivers supports flow-control as well? and sends pause frame when kernel module buffer is getting full?
Thanks, On Wed, Feb 11, 2015 at 2:36 AM, Luca Deri <[email protected]> wrote: > Behrooz, > flow control allows a NIC to report the sender that it can’t keep up with > the ingress speed. However this is just a hint for the sender (that it can > ignore it) and being it at L2, it is just for a link. This means that if > for reaching your peer you need to traverse several (L2) links, the flow > control won’t work. In short you will have drops even with flow control on. > > Luca > > On 09 Feb 2015, at 16:45, Behrooz Shafiee <[email protected]> wrote: > > Hello all, > > When using pf_ring without PF_RING aware drivers (normal kernel drivers) > there is always chance of losing packet even though the flow control is > activated on the driver. Because NAPI might read faster than application > and pf_ring kernel module buffer overflows and drops the packets while > kernel backlog queue is not full (in case of a slow application). > > Now my question is that, if I use PF_RING aware drivers with > flow-control 'on' is there still chance of losing packet? I assume because > there is no queue involved in between (except driver rings) droping packet > should not happen, because if driver rings are getting full the drivers > should send pause frame to sender. Is that correct? > > Thanks, > -- > Behrooz > _______________________________________________ > Ntop-misc mailing list > [email protected] > http://listgateway.unipi.it/mailman/listinfo/ntop-misc > > > > _______________________________________________ > Ntop-misc mailing list > [email protected] > http://listgateway.unipi.it/mailman/listinfo/ntop-misc > -- Behrooz
_______________________________________________ Ntop-misc mailing list [email protected] http://listgateway.unipi.it/mailman/listinfo/ntop-misc
