Prior to 4.3, tunnel vports (vxlan, gre and geneve) could transmit vxlan packets of any size, constrained only by the ability to send out the resulting packets. 4.3 introduced netdevs corresponding to tunnel vports. These netdevs have an MTU, which limits the size of a packet that can be successfully encapsulated. The default value for the MTUs are low (1500 or less), which is awkwardly small in the context of physical networks supporting jumbo frames, and leads to a conspicuous change in behaviour for userspace.
This patch series sets the MTU on openvswitch-created netdevs to be the relevant maximum (i.e. the maximum IP packet size minus any relevant overhead), effectively restoring the behaviour prior to 4.3. Where appropriate, the limits on MTU values when set on the netdevs directly are also relaxed. Changes in v2: * Extend to all openvswitch tunnel types, i.e. gre and geneve as well * Use IP_MAX_MTU David Wragg (3): vxlan: Relax the MTU constraints geneve: Relax MTU constraints vxlan, gre, geneve: Set a large MTU on ovs-created tunnel devices drivers/net/geneve.c | 29 +++++++++++++++++++++----- drivers/net/vxlan.c | 47 ++++++++++++++++++++++++++++++------------- include/net/ip_tunnels.h | 1 + net/ipv4/ip_gre.c | 7 +++++++ net/ipv4/ip_tunnel.c | 21 ++++++++++++++++--- net/openvswitch/vport-vxlan.c | 2 ++ 6 files changed, 85 insertions(+), 22 deletions(-) -- 2.5.0
