[dpdk-users] IPV4 and VLAN RX packets from NIC donot have the mbuf offload flag set with DPDK 18.08 version

Suchetha p suchetha2005 at gmail.com
Tue Jun 25 16:13:53 CEST 2019


After upgrading the DPDK to 18.08 version and RHEL 7.6 OS I observe that
offload flags were not set in the packets received from NIC for eth type
VLAN and IPV4.

Hence application had to explicitly set the offload flags for VLAN and IPV4

if (ETHER_TYPE_VLAN == eth_type) {
          m->ol_flags |= PKT_RX_VLAN_PKT;

    if (ETHER_TYPE_IPv4 == eth_type) {
          m->ol_flags |= PKT_RX_IPV4_HDR;

If these offload flags were not set in the mbuf the packet would get
dropped and will not be forwarded to the Tap device.

But the offload flag setting per NIC received packet is causing some
performance issue and delay in data transfer.

TCP segment loss and retransmissions are observed and TX Tap drops are

These changes with respect to offload flag setting for RX VLAN and IPV4
packet was not required with old DPDK and RHEL6 and packets were getting
forwarded from NIC to Tap device and vice versa without any issue.

So is anything changed with respect to DPDK and RHEL 7 for ingress packets ?

    Also let me know if  CKSUM/ offload flags for TCP packets needs to be
set with latest DPDK 18.08 to avoid TCP segment loss /DUP ACK and
retransmissions .



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