The UDP packet source IP address is changed by the KVM host

[SBhat29]

Hi,

When the DPDK UDP packets passes from the guest machine to host machine which is using the KVM SRIOV(Intel 82599) the source IP address in the IP header of the UDP packet is changed by the host along with the VLAN tagging insertion by the host. The changed IP address is not configured on the host. The ifconfig output /netstat  doesn't show this IP address. I am not sure why this source IP address in the IP header of the UDP packet is changed by the  host? Please let me know how to debug this ?And what configuration changes are required to prevent this IP address change ?

Due to this source IP address change the UDP packet is not processed by the destination.

Regards,

Shalini

[SBhat29]

Hi,

UDP checksum cannot be computed by Hardware virtualization( Intel 82599 SRIOV PCI passthrough, DPDK v1.7).UDP bad checksum errors are observed in the tcpdump(pcap) collected after host on the Service router when the UDP checksum computation is Hardware offloaded.Is this a known issue? UDP checksum is set  to 0  and Hardware offloading is disabled to prevent the UDP checksum errors.

Is this the only way out?Please suggest.

Thanks,