Hello,

Enviroment information;

DPDK versiyon 17.05

Kernel version 4.4.0

OS – Ubuntu 16.05

INTEL NIC XL710

Last i40e driver and NVM is installed.

ethtool -k ens2f2 :

tx-checksumming: on

tx-checksum-ipv4: on

tx-checksum-ip-generic: off [fixed]

tx-checksum-ipv6: on

tx-checksum-fcoe-crc: off [fixed]

tx-checksum-sctp: on

rx-fcs: off [fixed]

rx-all: off [fixed]

What is CRC or FCS :

https://www.firewall.cx/networking-topics/ethernet/ethernet-frame-formats/201-ethernet-ii.html

State:

• Even if strip_crc flag is up in port_config, NIC doesnt strip CRC.
• After stripping Ethernet Header from message-buf, CRC still there. So it breaks fragmentation when specific byte length income. For Example; Message with IP  header -> 1480, Ether Header 6+6+2 = 14 byte. Frame length looks 1498 byte.  Looks like 4 byte Crc, it has. After Ether header is stripped , 1488 byte left.

[code]

static struct rte_eth_conf port_conf = {

    .rxmode =

        {

            .header_split   = 0, /* Header Split disabled */

            .hw_ip_checksum = 0, /* IP checksum offload disabled */

            .hw_vlan_filter = 0, /* VLAN filtering disabled */

            .jumbo_frame    = 0, /* Jumbo Frame Support disabled */

            .hw_strip_crc   = 1, /* CRC stripped by hardware */

        },

    .txmode =

        {

            .mq_mode = ETH_MQ_TX_NONE,

        },

};

[/code]

Is there any function to strip CRC bytes or what is best way? Big thanks to help.

I have an idea that,

After stripping Ethernet Header ,

• If total length of message is bigger than IP header length , there is a CRC, it needs to strip somehow?
• If total length of message is equal to IP header length, no problem.
• If total length of message is less than IP header length, message is broken.

Best Regards.

___

Yasin CANER

Lider Mühendis

Ulak Haberleşme A.Ş. Ankara