Hi All, Do we have any resolution for this issue yet ? This looks like a defect in DPDK 18.08.
Plz share if anyone have any inputs on this issue. Regards Hirok On Sat, Apr 20, 2019 at 9:41 AM Anupama Laxmi <[email protected]> wrote: > We have recently upgraded to DPDK 18.08 version. After upgrading to the > latest version observing issue with UDP packets transmission errors for few > packets ( UDP size 736 bytes) .With older version of DPDK we never faced > this issue. > > Attaching the filtered tcpdump which shows "Bad UDP length > IP payload > length" for one such packet. > > No issue observed while transferring UDP packets with size 28 bytes and 48 > bytes. I tried to print the packet length calculation in my program just > before sending it out to the Kernel using rte_kni_tx_burst. The packet > length calculation seems correct to me. > > 1.) > size_udp:48 > sizeof(struct udp_hdr):8 > size_ApplMsg:40 > udphdr->dgram_len:12288 > m->data_len:82 > size_ip:68 > l2_data_shift:14 > > 2.) > size_udp:28 > sizeof(struct udp_hdr):8 > size_ApplMsg:20 > udphdr->dgram_len:7168 > m->data_len:62 > ip->total_length:12288 > size_ip:48 > l2_data_shift:14 > > *** Packets with UDP size 736 are not getting transmitted to the > receiving end and getting dropped. > > 3.) > size_udp:736 > sizeof(struct udp_hdr):8 > size_ApplMsg:728 > udphdr->dgram_len:57346 > m->data_len:770 > size_ip:756 > l2_data_shift:14 > > Also MTU is set to 1500 in my program. So it shouldn't be an issue to > transfer 736 bytes UDP data which is less than 1500 bytes MTU. > > Looks like the kernel is dropping this packet. > > So I tried to increase the kernel buffer size but that didn't help. > > netstat -su -> output shows 0 send/receive buffer errors. > > > What has changed in DPDK 18.08 with respect to UDP packets? Please suggest > if I need to consider tuning udp ( using new API ) , offloading udp > traffic(new offload flags) to resolve this issue. > > Thanks, > -------------- next part -------------- > A non-text attachment was scrubbed... > Name: bad_udp_length.png > Type: image/png > Size: 56015 bytes > Desc: not available > URL: < > http://mails.dpdk.org/archives/users/attachments/20190420/f5dd6779/attachment.png > > > -- Regards, -Hirok
