Re: [dpdk-dev] DPDK packet capture question

[Matthew Hall <mhall@mhcomputing.net>]

On Jun 21, 2015, at 5:09 PM, Daeyoung Kim <kdy1029@gmail.com> wrote:
> I am a newbie to DPDK.

Welcome!

> I'm making a packet capture program from the l3fwd
> sample application. When I tested my program in a virtual environment, it
> worked. But in a real world, it does not work correctly.

This topology is kind of complicated.

I recommend beginning with just a single port sending ARPs, pings, etc. It takes a lot of careful work to get everything right.

Switches are going to drop some packets from different ports depending on the MAC addresses they learn from the traffic.

So if there is a switch, when beginning it is good to enable a mirror mode on two systems communicating, and sending the mirror to the DPDK port that is listening. Or use some kind of cheap 100BaseT network tap (Gigabit-plus active taps are very expensive, and not needed for simple uses like this anyway, as you don't usually send heavy traffic when just debugging).

There is also a promiscuous flag in DPDK which you usually end up needing to set if you are doing special-purpose stuff...

rte_eth_promiscuous_enable(port_id)

Good luck, happy hacking!
Matthew.