Re: [PATCH net-next v1 0/3] Flow Based GTP Tunneling

On 12 July 2017 at 17:44, Jiannan Ouyang [off-list ref] wrote:

This patch series augmented the existing GTP module to support flow
based GTP tunneling and modified the openvswitch datapath to support the
GTP vport type.

A flow based GTP net device enables that,
1) on the RX path, the outer (IP/UDP/GTP) header information could to be
stored in the metadata_dst struct, and embedded into the skb.
2) on the TX path, packets are encapsulated following instructions in
the metadata_dst field of the skb.

A flow based GTP net device can be integrated with Open vSwitch, which
allows SDN controllers to program GTP tunnels via Open vSwitch.

Open vSwitch changes are based on patch set
    [PATCH] Add GTP vport based on upstream datapath

Example usage with OVS:

ovs-vsctl add-port br0 gtp-vport -- set interface gtp-vport \
    ofport_request=2 type=gtp option:remote_ip=flow options:key=flow

ovs-ofctl add-flow br0
    "in_port=2,tun_src=192.168.60.141,tun_id=123, \
    actions=set_field:02:00:00:00:00:00->eth_src, \
    set_field:ff:ff:ff:ff:ff:ff->eth_dst,LOCAL"

ovs-ofctl add-flow br0 \
    "in_port=LOCAL,actions=set_tunnel:888, \
    set_field:192.168.60.141->tun_dst,2"

arp -s 10.1.1.122 02:00:00:00:00:00

Jiannan Ouyang (3):
  gtp: refactor to support flow-based gtp encap and decap
  gtp: Support creating flow-based gtp net_device
  openvswitch: Add GPRS Tunnel Protocol (GTP) vport support

Hi Jiannan,

net-next is closed, Dave won't accept patches at this time.

Some brief feedback in regards to patch #3, the preference these days
is for OVS userspace to use rtnetlink to configure devices in
COLLECT_METADATA mode, then attach those devices as regular
vport-netdev device type to OVS kernel datapath. I think that should
mean that no kernel changes to openvswitch are required for providing
GTP vports. Instead of this patch it would require something similar
to the IFLA_GRE_COLLECT_METADATA flag which GRE has, but for the GTP
devices. The latest OVS master now supports configuring devices in
this way, perhaps you could take a look at OVS tree's
lib/dpif-netlink-rtnl.c to see how other tunnel devices are configured
and see if that makes sense for GTP as well?

Cheers,
Joe