Re: Client and server on same computer

[Ben Greear <greearb --at-- candelatech.com>]

Dag Bakke wrote:
> On 05/31/2007 09:55 AM, Daniel Janzon wrote:

> > This would be a dedicated machine. If the speed of the ethernet
> > card(s)  is significantly higher than the equipment under test,
> > I don't see how it could be a problem using a single machine.
>
>
> You may be in for a surprise. Any other traffic running over the same
> PCI-bus as your network card or consuming CPU cycles will likely affect
> your results negatively. What is the bandwidth of the bus the network
> interface sits on, and what devices share that bus?
>
> Even modern hardware can have problems filling a 100mbps link with small
> packets. (Too many interrupts to handle.) Certain GbE interfaces
> struggles really hard to receive 300 Mbps for any packetsize, and will
> definitely not be able to transmit that much.

An Intel pro/1000 NIC on a PCI-X or PCI-E bus will have no problem
sending or receiving 900+Mbps.  Using pktgen or similar on Linux you
can generate around 1 million (64k) packets per second using similar hardware.

This is more than adequate to fully utilize a large amount of wifi
equipment!

To make sure it's not your test system that is a bottle-neck, just use
loop-back ethernet cables instead of the network under test...

Ben



--
Ben Greear <greearb --at-- candelatech.com>
Candela Technologies Inc  http://www.candelatech.com