From: Tom Herbert <[email protected]> Date: Wed, 29 Apr 2015 15:33:21 -0700
> This patch divides the IPv6 flow label space into two ranges: > 0-7ffff is reserved for flow label manager, 80000-fffff will be > used for creating auto flow labels (per RFC6438). This only affects how > labels are set on transmit, it does not affect receive. This range split > can be disbaled by systcl. > > Background: > > IPv6 flow labels have been an unmitigated disappointment thus far > in the lifetime of IPv6. Support in HW devices to use them for ECMP > is lacking, and OSes don't turn them on by default. If we had these > we could get much better hashing in IPv6 networks without resorting > to DPI, possibly eliminating some of the motivations to to define new > encaps in UDP just for getting ECMP. > > Unfortunately, the initial specfications of IPv6 did not clarify > how they are to be used. There has always been a vague concept that > these can be used for ECMP, flow hashing, etc. and we do now have a > good standard how to this in RFC6438. The problem is that flow labels > can be either stateful or stateless (as in RFC6438), and we are > presented with the possibility that a stateless label may collide > with a stateful one. Attempts to split the flow label space were > rejected in IETF. When we added support in Linux for RFC6438, we > could not turn on flow labels by default due to this conflict. > > This patch splits the flow label space and should give us > a path to enabling auto flow labels by default for all IPv6 packets. > This is an API change so we need to consider compatibility with > existing deployment. The stateful range is chosen to be the lower > values in hopes that most uses would have chosen small numbers. > > Once we resolve the stateless/stateful issue, we can proceed to > look at enabling RFC6438 flow labels by default (starting with > scaled testing). > > Signed-off-by: Tom Herbert <[email protected]> Ok, applied, let's see what happens. Thanks Tom. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
