From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: vmxnet3 TX TCP/UDP checksum not getting computed
 with L2_len > 14
Date: Sun, 17 Jun 2018 09:46:26 -0700
Message-ID: <20180617094626.2d72413f@xeon-e3>
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Cc: dev@dpdk.org, yongwang@vmware.com
To: Padam Jeet Singh <padam.singh@inventum.net>
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On Sun, 17 Jun 2018 14:55:06 +0530
Padam Jeet Singh <padam.singh@inventum.net> wrote:

> Hello,
>=20
> Issue observed when using vmxnet3 based interface on packet with followin=
g structure is sent:
>=20
> Ethernet + PPPoE + PPP (22 bytes) as the Layer 2 header,=20
> IPv4 (20)=20
> UDP
> DNS Payload
>=20
> The tx offload value in this case is 0x0f0000000000000 (PKT_TX_IPV4  | PK=
T_TX_IP_CKSUM | PKT_TX_UDP_CKSUM)
>=20
> The checksum of the packet seen by the receiver shows incorrect checksum =
and it=E2=80=99s value is the pseudo checksum value that was set at the tim=
e of the TX. However the IP header checksum is correct.
>=20
> The same issue is not seen when the L2 header is a just the Ethernet (14 =
bytes).
>=20
> Also, with the same setup on the same hardware if we switch the driver fr=
om vmxnet3 to e1000e, all checksums are computed correctly.
>=20
> Is this a DPDK vmxnet3 driver bug or that of underlying esxi? The ESXi ve=
rsion is 6.0.0 (Build 3620759).
>=20
> Thanks,
> Padam

I don't think VMWare supports IP checksum offload. Since IP checksum is tri=
vial and in cache,
the IP header checksum offload is usually not a speed up anyway. Linux for =
example, never does
IP header checksum offload.