Re: Software router state of the art

["William Herrin" <herrin-nanog () dirtside com>]

On Wed, Jul 23, 2008 at 2:03 PM, Naveen Nathan <naveen () lastninja net> wrote:
> > The Endace DAG cards claim they can move 7 gbps over a PCI-X bus from
> > the NIC to main DRAM. They claim a full 10gbps on a PCIE bus.
>
> I wonder, has anyone heard of this used for IDS? I've been looking at
> building a commodity SNORT solution, and wondering if a powerful network
> card will help, or would the bottleneck be in processing the packets and
> overhead from the OS?

The first bottleneck is the interrupts from the NIC. With a generic
Intel NIC under Linux, you start to lose a non-trivial number of
packets around 700mbps of "normal" traffic because it can't service
the interrupts quickly enough.

The DAG card can be dropped in to replace the interface used for a
libpcap-based application. When I tested the 1gbps PCIE version, I
lost no packets to 1gbps and my capture application's CPU usage
dropped to about 1/5th of what it was with the generic NIC. YMMV.

Regards,
Bill Herrin


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