Update DPDK docs with note about using veth pairs

In case when ovs-dpdk is used together with ``ovs_use_veth`` config
option set to True, it cause invalid checksum on all packets send from
qdhcp namespace.
This commit adds short info about this limitation to ovs-dpdk config
guide.

Change-Id: I6237abab3d9e625440e95e75f5091d09a1ec44f0
Related-Bug: #1832021
This commit is contained in:
Slawek Kaplonski 2019-06-19 14:27:18 +02:00 committed by Brian Haley
parent a832a1d1b3
commit 051b58f566
1 changed files with 7 additions and 0 deletions

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@ -152,3 +152,10 @@ Known limitations
will not function. will not function.
* Expect performance degradation of services using tap devices: these devices * Expect performance degradation of services using tap devices: these devices
do not support DPDK. Example services include DVR, FWaaS, or LBaaS. do not support DPDK. Example services include DVR, FWaaS, or LBaaS.
* When the ``ovs_use_veth`` option is set to ``True``, any traffic sent
from a DHCP namespace will have an incorrect TCP checksum.
This means that if ``enable_isolated_metadata`` is set to ``True`` and
metadata service is reachable through the DHCP namespace, responses from
metadata will be dropped due to an invalid checksum. In such cases,
``ovs_use_veth`` should be switched to ``False`` and Open vSwitch (OVS)
internal ports should be used instead.