[dpdk-users] i40e: issues with TCP Segmenation Offload of VLAN-tagged traffic

[Alec Istomin]

Przemek,
 Please try to reduce MTU on your virtio interfaces and see if this changes the behavior. I had to use mtu 1496  to allow tagged connectivity in my environment.  Make sure to restart OVS after MTU change.

I did not use TSO (it's not working in OVS 2.5 and dpdk 2.2.0  that i use), but the symptoms look very familiar.

Regards,
 Alec

-----Original Message-----
From: users [mailto:users-bounces at dpdk.org] On Behalf Of Lal, PrzemyslawX
Sent: Friday, July 29, 2016 6:45
To: users at dpdk.org
Cc: Kavanagh, Mark B <mark.b.kavanagh at intel.com>; Ksiadz, MarcinX <marcinx.ksiadz at intel.com>; Siddiqui, Muhammad A <muhammad.a.siddiqui at intel.com>
Subject: [dpdk-users] i40e: issues with TCP Segmenation Offload of VLAN-tagged traffic

Hi,

I have problem with TCP Segmentation Offload of VLAN tagged traffic on i40e PMD driver - connectivity dies after trying to send first packet.
After spawning new VM non-TCP traffic (like ping) works fine. After trying to connect using SSH to the VM, connectivity is completely broken on i40e - even ping stops working. In the meanwhile connection between VMs connected to the same OVS using vhost-user ports works fine. 

This is how topology looks like (simplified):

     virtio             virtio    <-- TSO enabled on the virtio interface on virtual machine
       |                  |
    vhostuser          vhostuser  <-- TSO supported for vhost-user interfaces in DPDK since 16.04 release
       |                  |
    ovs-dpdk           ovs-dpdk   <-- VLAN tagging/untagging done in OVS-DPDK using OpenFlow rules
       |                  |
  rte_i40e_pmd       rte_i40e_pmd <-- first packet that should be offloaded breaks connectivity
       |                  |
       +----TOR switch----+

Problem occurs only with i40e NIC - when using exactly the same configuration with ixgbe NIC everything works fine, it looks like i40e PMD driver causes this problem.

Versions tested:
DPDK - 16.04, 16.07-rc3, also some post 16.07-rc2 master tested with this patch applied http://dpdk.org/ml/archives/dev/2016-July/043924.html
OVS-DPDK - recent versions from master branch with TSO RFC patch applied on top - link: http://openvswitch.org/pipermail/dev/2016-June/072871.html

In each case TSO and VLAN combo on ixgbe was working with no issues, on i40e it was always broken.

Issue was also independently reproduced by Mark Kavanagh (cc'd).

Is this known issue and is there any way to solve this issue? If not, are there any plans to fix this problem in the upcoming DPDK releases?
	
Best Regards,
Przemek