This patch is not in line with the ongoing work to support L3 tunnels on
legacy (non packet type-aware) OVS bridges as specified in
https://docs.google.com/document/d/1oWMYUH8sjZJzWa72o2q9kU0N6pNE-rwZcLH3-kbbDR8/edit?usp=sharing
To avoid extensive rework, we suggest to replace the patch with
This commit relaxes the assumption that all packets have an Ethernet
header, and adds support for layer 3 flows. For each packet received on
the Linux kernel datapath the l2 and l3 members of struct ofpbuf are
intialized appropriately, and some functions now expect this (notably
flow_extract()),
