On Mon, Mar 25, 2019 at 5:44 PM <nusid...@redhat.com> wrote:
>
> From: Numan Siddique <nusid...@redhat.com>
>
> This patch adds a new action - 'check_pkt_len' which checks the
> packet length and executes a set of actions if the packet
> length is greater than the specified length or executes
> another set of actions if the packet length is lesser or equal to.
>
> This action takes below nlattrs
> * OVS_CHECK_PKT_LEN_ATTR_PKT_LEN - 'pkt_len' to check for
>
> * OVS_CHECK_PKT_LEN_ATTR_ACTIONS_IF_GREATER - Nested actions
> to apply if the packet length is greater than the specified 'pkt_len'
>
> * OVS_CHECK_PKT_LEN_ATTR_ACTIONS_IF_LESS_EQUAL - Nested
> actions to apply if the packet length is lesser or equal to the
> specified 'pkt_len'.
>
> The main use case for adding this action is to solve the packet
> drops because of MTU mismatch in OVN virtual networking solution.
> When a VM (which belongs to a logical switch of OVN) sends a packet
> destined to go via the gateway router and if the nic which provides
> external connectivity, has a lesser MTU, OVS drops the packet
> if the packet length is greater than this MTU.
>
> With the help of this action, OVN will check the packet length
> and if it is greater than the MTU size, it will generate an
> ICMP packet (type 3, code 4) and includes the next hop mtu in it
> so that the sender can fragment the packets.
>
> Reported-at:
> https://mail.openvswitch.org/pipermail/ovs-discuss/2018-July/047039.html
> Suggested-by: Ben Pfaff <b...@ovn.org>
> Signed-off-by: Numan Siddique <nusid...@redhat.com>
> CC: Gregory Rose <gvrose8...@gmail.com>
> CC: Pravin B Shelar <pshe...@ovn.org>
> ---
> v1 -> v2
> -----
> * Addressed the review comments.
> - Removed the vlan-tag length when checking the packet length
> - Reordered the netlink attributes
> - Changed the comments to use 'attribute' instead of 'action'
>
> Corresponding OVS patch (submitted as RFC for now) which makes use of this
> action can be
> found here - https://patchwork.ozlabs.org/patch/1059081/
>
Looks good to me.
Acked-by: Pravin B Shelar <pshe...@ovn.org>
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