why DPDK reassembles IP fragment packets with AF_PACKET

[Stephen Hemminger]

On Mon, 8 Jan 2024 19:07:20 +0800 (CST)
钟 <gdsgsx2002 at 163.com> wrote:

> Hi All,
> 
> 
> Recently I debug ovs-dpdk with AF_PACKET mode.  When IP fragment packets are received via DPDK, the IP fragment packets are reassembled by DPDK. After reassembly, the packet length is over 1518. They are discarded by OVS because of oversize packets.
> 
> 
> I don't understandy why  PACKET_FLAG_DEFRAG is set for AF_PACKET mode.
> 
> 

Not sure, but it looks like the af_packet wants to hash packets for fanout.
Hashin of fragments won't work correctly, and packet will arrive on different queues if fragmented.