[dpdk-users] Why is udp packet, sent by dpdk, received with zero'd payload?

[David Aldrich]

I think this is where my lack of understanding is my problem.  Looking at
the mbuf dump:

dump mbuf at 0x53e4e92c0, iova=73e4e9340, buf_len=2176
  pkt_len=57, ol_flags=c0000000000000, nb_segs=2, in_port=65535
  segment at 0x53e4e92c0, data=0x53e4e9396, data_len=42
  Dump data at [0x53e4e9396], len=42
00000000: 94 40 C9 1F C4 DB 94 40 C9 1E 13 7D 08 00 45 B8 | . at .....@...}..E.
00000010: 00 2B 00 00 00 00 40 11 F5 E8 C0 A8 01 69 C0 A8 | .+.... at ......i..
00000020: 01 68 0B B9 0B B8 00 17 64 2D |  |  |  |  |  |  | .h......d-
  segment at 0x53e146e40, data=0x53e4fbbc0, data_len=15
  Dump data at [0x53e4fbbc0], len=15
00000000: 48 65 6C 6C 6F 20 66 72 6F 6D 20 64 70 64 6B |  | Hello from dpdk

It consists of two parts (segments?), of lengths 42 and 15. This makes
sense to me as I first
put the payload in the mbuf (15 bytes) and then added the Ethernet and
L3 headers (42 bytes) by calling rte_pktmbuf_prepend().

I guess only the first segment is getting transmitted?


On Wed, Jul 1, 2020 at 1:57 PM Cliff Burdick <shaklee3 at gmail.com> wrote:

> Are you setting data_len and packet_len in the mbuf before sending?
>
>
> On Wed, Jul 1, 2020, 03:23 David Aldrich <david.aldrich.ntml at gmail.com>
> wrote:
>
>>  Hi,
>>
>> I have a problem transmitting udp packets with dpdk-stable-18.11.8. I have
>> posted a question about it on stackoverflow:
>>
>>
>> https://stackoverflow.com/questions/62674596/why-is-udp-packet-sent-by-dpdk-received-with-zerod-payload
>>
>> I would be grateful for any comments either there or in this group please.
>>
>> Best regards
>>
>> David
>>
>