[dpdk-users] ipv4 fragmentation

[Matt Laswell]

I've found that if both the packet length and data length fields in an mbuf
aren't set properly, DPDK will quietly drop it on the floor when I try to
send it.  I don't know if that's the cause of your problems, but it's one
of the first places that I would look.

--
Matt Laswell
Principal Software Engineer, infinite io
laswell at infinite.io


On Fri, Aug 12, 2016 at 12:32 PM, Александр Киселев <kiselev99 at gmail.com>
wrote:

> Hi!
>
> I am trying to use rte_ipv4_fragment_packet() function, but so far all
> attemps has been unsuccessful.
>
> Fragment function gets a packet, successfuly splits it to the two packets,
> then I add an L2 header to the each of resulting fragments
> and send the fragments using rte_eth_tx_burst() to the wire. All steps of
> the above process are succesfully completed without any error, but I don't
> see the fragments on the wire and PMD stat function also reports that no
> packets were transmitted.
>
> I've rechecked many times that L2 header of each fragments is correct, that
> values of l2_len and l3_len rte_mbuf members are correct,
> that the rte_eth_tx_burst() result is correct (2 packets). The sizes of
> fragments are also correct.
>
> What did I miss?
>
> I am using DPDK 2.2.0 and ixgbe PMD driver.
>
> This is some log data of a test run.
> ==
> ==
> The original packet that has to be fragmented (including L2 header data)
>
> dump mbuf at 0x0x7f7d103870c0, phys=215787140, buf_len=2176
>   pkt_len=2546, ol_flags=40000000000003, nb_segs=2, in_port=0
>   segment at 0x0x7f7d103870c0, data=0x0x7f7d103871c0, data_len=1518
>   Dump data at [0x7f7d103871c0], len=50
> 00000000: 00 1B 21 3C 69 45 90 E2 BA 00 3C CC 81 00 00 86 |
> ..!<iE....<.....
> 00000010: 08 00 45 00 09 E0 7E D1 00 00 40 01 00 00 C0 A8 |
> ..E...~... at .....
> 00000020: 7D 01 C0 A8 7D 02 00 00 FD FD 0B 2D 00 01 56 FF |
> }...}......-..V.
> 00000030: AD 57 |  |  |  |  |  |  |  |  |  |  |  |  |  |  | .W
>   segment at 0x0x7f7d10386780, data=0x0x7f7d103868a6, data_len=1028
>
>
> fragmentation is needed. mtu 1500, pkt len 2546, data len 1518, l2 len 18,
> l3 len 20
> num fragment needed: 2
>
> ==
> ==
> Fragments (including L2 header data):
>
> fragment #0, pkt len 1518, l2 len 18, l3 len 20, data len 38
>
> dump mbuf at 0x0x7f7d10388340, phys=2157883c0, buf_len=2176
>   pkt_len=1518, ol_flags=40000000000000, nb_segs=2, in_port=255
>   segment at 0x0x7f7d10388340, data=0x0x7f7d1038842e, data_len=38
>   Dump data at [0x7f7d1038842e], len=38
> 00000000: 00 1B 21 3C 69 45 90 E2 BA 00 3C CC 81 00 00 86 |
> ..!<iE....<.....
> 00000010: 08 00 45 00 05 DC 7E D1 20 00 40 01 00 00 C0 A8 | ..E...~.
> . at .....
> 00000020: 7D 01 C0 A8 7D 02 |  |  |  |  |  |  |  |  |  |  | }...}.
>   segment at 0x0x7f7d0ef87dc0, data=0x0x7f7d103871e6, data_len=1480
>   Dump data at [0x7f7d103871e6], len=12
> 00000000: 00 00 FD FD 0B 2D 00 01 56 FF AD 57 |  |  |  |  | .....-..V..W
>
>
> fragment #1, pkt len 1066, l2 len 18, l3 len 20, data len 38
>
> dump mbuf at 0x0x7f7d10388c80, phys=215788d00, buf_len=2176
>   pkt_len=1066, ol_flags=40000000000000, nb_segs=2, in_port=255
>   segment at 0x0x7f7d10388c80, data=0x0x7f7d10388d6e, data_len=38
>   Dump data at [0x7f7d10388d6e], len=38
> 00000000: 00 1B 21 3C 69 45 90 E2 BA 00 3C CC 81 00 00 86 |
> ..!<iE....<.....
> 00000010: 08 00 45 00 04 18 7E D1 00 B9 40 01 00 00 C0 A8 |
> ..E...~... at .....
> 00000020: 7D 01 C0 A8 7D 02 |  |  |  |  |  |  |  |  |  |  | }...}.
>   segment at 0x0x7f7d0ef87480, data=0x0x7f7d103868a6, data_len=1028
>   Dump data at [0x7f7d103868a6], len=12
> 00000000: C0 C1 C2 C3 C4 C5 C6 C7 C8 C9 CA CB |  |  |  |  | ............
> lcore 1 SEND
>
> ==
> ==
> sending 2 packets
> sending result: 2
>
>
> --
> --
> Kiselev Alexander
>