Hi Olivier, On Wed, Jan 28, 2015 at 8:39 PM, Olivier MATZ <olivier.matz at 6wind.com> wrote:
> Hi Prashant, > > > On 01/28/2015 03:57 PM, Prashant Upadhyaya wrote: > >> I am using dpdk 1.6r1, intel 82599 NIC. >>>> I have an mbuf, I have hand-constructed a UDP packet (IPv4) in >>>> the data >>>> portion, filled the relevant fields of the headers and I do a tx >>>> burst. No >>>> problems, the destination gets the packet. I filled UDP checksum >>>> as zero >>>> and there was no checksum offloaded in ol_flags. >>>> >>>> Now in the same usecase, I want to offload UDP checksum. >>>> I am aware that the checksum field in UDP header has to be >>>> filled with the >>>> pseudo header checksum, I did that, duly added the >>>> PKT_TX_UDP_CKSUM flag in >>>> ol_flags, did a tx_burst and the packet does not reach the >>>> destination. >>>> >>>> I realized that I have to fill the following fields as well (my >>>> packet does >>>> not have vlan tag) >>>> mbuf->pkt.vlan_macip.f.l2_len >>>> mbuf->pkt.vlan_macip.f.l3_len >>>> >>>> so I filled the l2_len as 14 and l3_len as 20 (IP header with no >>>> options) >>>> Yet the packet did not reach the destination. >>>> >>>> So my question is -- am I filling the l2_len and l3_len >>>> properly ? >>>> Is there anything else to be done before I can get this UDP >>>> checksum >>>> offload to work properly for me. >>>> >>> >>> >>> >>> As far as I remember, this should be working on 1.6r1. >>> When you say "did not reach the destination", do you mean that the >>> packet is not transmitted at all? Or is it transmitted with a wrong >>> checksum? >>> >> >> >> The packet is not transmitted to destination. I cannot see it in tcpdump >> at wireshark. >> If I don't do the offload and fill UDP checksum as zero, then >> destination shows the packet in tcpdump >> If I don't do the offload and just fill the pseudo header checksum in >> UDP header (clearly the wrong checksum), then the destination shows the >> packet in tcpdump and wireshark decodes it to complain of wrong UDP >> checksum as expected. >> > > This is strange. I don't see anything obvious in what you are > describing. It looks like the packet is dropped in the driver > or in the hardware. You can check the device statistics. > > Another thing you can do is to retry on the latest stable dpdk which > is known to work (see csumonly.c in test-pmd). > > Let me add further, I am _just_ doing the UDP checksum offload and not >> the IP hdr checksum offload. I calculate and set IP header checksum by >> my own code. I hope that this is acceptable and does not interfere with >> UDP checksum offload >> > > This should not be a problem. > > Indeed it worked with DPDK1.7 and then I retried with DPDK1.6 and it worked there too. Must have been some mistake at my end, may be I did not clean properly when I was experimenting with some values of l2_len. Sorry for the botheration to the list. While we are at it, a quick question -- in case I have an mbuf chain whose payloads constitute a UDP packet, should I setup the ol_flags and the l2_len, l3_len fields only in the first mbuf header of the chain or in all the mbuf headers of the chain ? > Regards, > Olivier > >
