Re: [RFC PATCH 1/1] net/ipv4: Enable flow-based ECMP

[Michal Kubecek <mkubecek@suse.cz>]

On Tue, Jul 28, 2015 at 02:27:57AM +0000, Richard Laing wrote:
> From: Richard Laing <richard.laing@alliedtelesis.co.nz>
> 
> Enable flow-based ECMP.
> 
> Currently if equal-cost multipath is enabled the kernel chooses between
> equal cost paths for each matching packet, essentially packets are
> round-robined between the routes. This means that packets from a single
> flow can traverse different routes. If one of the routes experiences
> congestion this can result in delayed or out of order packets arriving
> at the destination.
> 
> This patch allows packets to be routed based on their
> flow - packets in the same flow will always use the same route. This
> prevents out of order packets. There are other issues with round-robin
> based ECMP routing related to variable path MTU handling and debugging.
> See RFC2991 for more details on the problems associated with packet
> based ECMP routing.
> 
> This patch relies on the skb hash value to select between routes. The
> selection uses a hash-threshold algorithm (see RFC2992).
> 
> Signed-off-by: Richard Laing <richard.laing@alliedtelesis.co.nz>

The patch looks corrupted (long lines split, tabs converted to (four?)
spaces etc.

                                                        Michal Kubecek