[dpdk-dev] DPDK packet capture question

Matthew Hall mhall at mhcomputing.net
Mon Jun 22 04:40:06 CEST 2015


On Jun 21, 2015, at 5:09 PM, Daeyoung Kim <kdy1029 at 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.



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