[dpdk-dev] vmxnet3 TX TCP/UDP checksum not getting computed with L2_len > 14

Padam Jeet Singh padam.singh at inventum.net
Sun Jun 17 11:25:06 CEST 2018


Hello,

Issue observed when using vmxnet3 based interface on packet with following structure is sent:

Ethernet + PPPoE + PPP (22 bytes) as the Layer 2 header, 
IPv4 (20) 
UDP
DNS Payload

The tx offload value in this case is 0x0f0000000000000 (PKT_TX_IPV4  | PKT_TX_IP_CKSUM | PKT_TX_UDP_CKSUM)

The checksum of the packet seen by the receiver shows incorrect checksum and it’s value is the pseudo checksum value that was set at the time of the TX. However the IP header checksum is correct.

The same issue is not seen when the L2 header is a just the Ethernet (14 bytes).

Also, with the same setup on the same hardware if we switch the driver from vmxnet3 to e1000e, all checksums are computed correctly.

Is this a DPDK vmxnet3 driver bug or that of underlying esxi? The ESXi version is 6.0.0 (Build 3620759).

Thanks,
Padam


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